Rally Cars tech stuff

[OldF]

Suddenly remembered this post.


We have to define when we say boost pressure whqat we mean.
Some people mean the overboost pressure,some other the ct boost pressure.
overboost is the turbo pressure we have at midrange rpm when turbo spools,ct boost pressure is when the rpms are at the higher band ie 5000-6000rpm etc. big overboost pressure help to create more torque,while big ct pressure will help to have bigger number at peak horsepower.

Please explain more. I have always though that when you say overboost you mean the boost above atmospheric pressure or in other words the gauge pressure whatever the revs are. Ct is unknown term for me.

Sometimes people are discussing about same issue using different words, which can cause confusion. When I speak about boost I mean the pressure above atmospheric pressure.

In the book by Graham Bell (Forced induction performance tuning) he defines the pressures as follows.

Gauge pressure: “The pressure you read of a normal pressure gauge. This is the pressure above atmospheric pressure. Usually simply called the boost pressure when referring to the inlet manifold pressure in supercharged engines.”

Absolute pressure: “The pressure above perfect vacuum. Thus, at sea level, normal air pressure is 14,7 psi absolute. Adding supercharged boost of 5 psi would then give a reading of 19,7 psi absolute.”


example grN evos can create about 2 bar overboost,but cant ''hold'' more than 1,5-1,6 bar at high revs with restrictor.All these are not rule,but depents to external temperatures a lot.

I recall you once said that a gr N evo has 0,5 – 0,7 bar at 4500 rpm.


At Finland-Sweden Norway or at mediterannean winter cold rallies you can,but at summer rallies with 30+ temp is difficult.

I think it’s all about air density that changes with altitude, temperature and to some extent the humidity (100% relative humidity decreases the density by only 0,9% compared to dry air at sea level and 20 oC).

As known the wrc cars are said to loose 20-30% of the power in higher altitudes in Mexico. I compared the density at sea level with temperatures + 20 oC (1,204 kg/ m3) and - 20 oC (1,394 kg/ m3). The density is 15,8% higher with – 20 oC. Does this mean that the power also increases by 15,8%? Assuming a car having 330 PS at sea level at + 20 oC it would mean 382 PS at - 20 oC! Ups!

Air Density Calculations Impact of Altitude Temperature Humidity and Pressure.xlsx (http://www.baranidesign.com/air-density/air-density.htm)

Dimviii, if this is true you should come up north and run your Mitsu in the dyno. You would get good results. ;)


Wrc cars now can have a 2,5 bar overboost(as the limit) and for sure can hold much more ct pressure from an N4-R4 due to less cc(1600 vs 2000) and different boost pressure hardware system.

My opinion is still that it’s 2,5 bar absolute (atmospheric pressure + turbo pressure / gauge pressure).

Sorry for late reply.

[dimviii]

yes its absolute pressure,thats the way everybody works at engines reffering.
About the density at low temps,yes it helps a lot cause the air density is higher,but no way if 20% more density will have 20% more power.As you drive the car yes you can feel the better response,the more power,but lets say that at a 350 bhp car feels like some 15-20bhp more.I am talking about temp difference from +30 celsious to 5 celsious.
Another point is with less temp you have less intake temps, due to colder air through the intercooler which helps to decrease the hot compressed air from turbocharger.

About the ''overboost'' and ''ct''
lets say that you drive an Mitsubishi evo(or any turbo car with wastegate actuator) you are driving the car with 4th gear and 2000rpms,and you floor the gas pedal.Car will accelerate slowly at first(rpm range out of turbo at 2000rpms) and as the rpms climb to about 2700 turbo starts t build pressure.At about 3500rpms your absolute air pressure gauge reach its maximum pressure which is lets say 1,8 bar.At about 4500-5000rpms if you watch your boost gauge you will see that the boost pressure starts to drop slowly at 1,7-1,6-1,5bar.At 7000rpms your boost gauge will show 1,3 bar.This pressure is the ''ct''
The 1,8bar the maximum pressure your engine reach at 3500rpm is the ''overboost''
Why this happening?
We want more boost pressure at mid range rpms to help the car accelerate faster.As the rpms go up,we cant hold that pressure(1,8bar) for many reasons.Turbo not big enough,at grN cars just 33mm intake at turbo,turbo at continious 1,8bar will heat A LOT the air,and the oem intercooler will not succeed to low the intake temps etc.The reasons vary from car to car,so dont take it as a rule for all cars-engines.
At wrc cars we dont have overboost and ct.We have a steady boost pressure from mid range to high revs.At wrc we have big enough turbos,we have better efficient intercoolers,stronger engines that can cope with 2,5 bar all day(s) long,completely different boost pressure management and hardware.

Hope to helped with my s$ite English. :dozey:
if you didn t understant something dont hesitate to ask again.

[Mirek]

By WRC cars do You mean 1.6T cars with lower boost compared to 2.0T? Because I have a turbo pressure curve from an early Fabia WRC Evo I engine and it looks like the one of Gr.N cars just has much higher values but the decrease is same (I think it must be similar with the restrictor).

It starts around 2700 rpm with something like 2 bars at 3000 rpm. It reaches maximum cca 3,3 bar at 3500 rpm but than it starts to decrease to 2,9 bar at 4000 rpm, 2,3 bar at 5000, 1,9 bar at 6000 rpm and finally some 1,4 bar at rpm limiter at 7500 rpm. Numbers are approximate, the grid is quite large.

The engine has max. torque at 3700 rpm and maximum power constant from 4000 to 5000 rpm.

[dimviii]

Mirek the dynoplot i ve seen from escort wrc, was almost steady pressure to 6000 rpms and after that started to drop.From 3000 rpms had already 3 bars.Unfortunately haven t seen from later wrc cars,or the new 1,6 ones.
Of course restrictors doesn t help to keep high pressures at high rpms,but depents to turbo design,engine efficient,for how many rpms will manage to keep the boost.

ps the escort wrc i ve seen is with 38mm restrictor

[stefanvv]

How's the ALS affect all this, Mitsubishi's ones sound lot agressive to me, unlike Subaru's and WRC/RRC?

[dimviii]

How's the ALS affect all this, Mitsubishi's ones sound lot agressive to me, unlike Subaru's and WRC/RRC?
every als can adjust to aggresive or less agresive.Driver will choose how aggresive to his likes at every surface.

[Coach 2]

I saw a dyno from Subaru that had 2,9 from very low (think it was 2000 rpm) to almost 7000. I also ask PS if that was right, and he said yes. Think it was the 12B.

[dimviii]

I saw a dyno from Subaru that had 2,9 from very low (think it was 2000 rpm) to almost 7000. I also ask PS if that was right, and he said yes. Think it was the 12B.

yes its possible from so low revs with agressive antilag to build plenty of boost pressure.

[OldF]

Thanks, now I know the difference between overboost and ct but what does ct stands for?

The explanation you gave I assume is about an evo without a restrictor because otherwise I can’t understand 1,3 bar @ 7000 rpm.

Below is a dyno chart for a evo9 I got from a Finnish company that tunes cars with turbo (Google Translate (http://translate.google.com/translate?sl=fi&tl=en&js=n&prev=_t&hl=en&ie=UTF-8&eotf=1&u=http%3A%2F%2Fwww.turbotec.com%2Fhenkiloautot%2Fe tusivu%2Fmalli.php%3Fvalmistaja%3DMitsubishi%26kor imalli%3DLancer).)

MitsubishiEvo9Stage1_21_zpsc5d4ccdf.jpg%20photo%20 by%20OkdF%20|%20Photobucket (http://s267.beta.photobucket.com/user/OkdF/media/MitsubishiEvo9Stage1_21_zpsc5d4ccdf.jpg.html?sort= 3&o=0)

The lowest is a standard car. The next one is as they call it stage 1 with a power of 326 PS @ 1,5 bar. The most upper one have 355 PS @ 1,6 bar (Stage 2).

On an evo with restrictor I assume the pressure will decrease rapidly after torque peak because of the restrictor. On the chart below the torque decreases rapidly after peak torque -> pressure drop in the inlet manifold. As I said I recall you said about 0,5 – 0,7 bar at 4500 rpm.

Mitsu_Evo9_grpN_Dyno-1_zps3780d166.jpg%20photo%20by%20OkdF%20|%20Photob ucket (http://s267.beta.photobucket.com/user/OkdF/media/Mitsu_Evo9_grpN_Dyno-1_zps3780d166.jpg.html?sort=3&o=1)

Max rengas teho = max power from the wheels
Max moottori teho = max power from the engine
Max momentti = max torque
Max nopeus = max speed
Ilmapaine = atmospheric pressure
Lämpötila = temperature

[TyPat107]

How's the ALS affect all this, Mitsubishi's ones sound lot agressive to me, unlike Subaru's and WRC/RRC?

I have always wondered how other Mitsubishi did their anti-lag as compared to the "rocket" system that Prodrive used. For that matter how do the modern systems from vw Citroen and ford work?

(really loving the technical discussion, is there any way to start another thread about it so we don't anger brother John and lose all this great info?)

[dimviii]

Thanks, now I know the difference between overboost and ct but what does ct stands for?

The explanation you gave I assume is about an evo without a restrictor because otherwise I can’t understand 1,3 bar @ 7000 rpm.

Below is a dyno chart for a evo9 I got from a Finnish company that tunes cars with turbo (Google Translate (http://translate.google.com/translate?sl=fi&tl=en&js=n&prev=_t&hl=en&ie=UTF-8&eotf=1&u=http%3A%2F%2Fwww.turbotec.com%2Fhenkiloautot%2Fe tusivu%2Fmalli.php%3Fvalmistaja%3DMitsubishi%26kor imalli%3DLancer).)

MitsubishiEvo9Stage1_21_zpsc5d4ccdf.jpg%20photo%20 by%20OkdF%20|%20Photobucket (http://s267.beta.photobucket.com/user/OkdF/media/MitsubishiEvo9Stage1_21_zpsc5d4ccdf.jpg.html?sort= 3&o=0)

The lowest is a standard car. The next one is as they call it stage 1 with a power of 326 PS @ 1,5 bar. The most upper one have 355 PS @ 1,6 bar (Stage 2).

On an evo with restrictor I assume the pressure will decrease rapidly after torque peak because of the restrictor. On the chart below the torque decreases rapidly after peak torque -> pressure drop in the inlet manifold. As I said I recall you said about 0,5 – 0,7 bar at 4500 rpm.

Mitsu_Evo9_grpN_Dyno-1_zps3780d166.jpg%20photo%20by%20OkdF%20|%20Photob ucket (http://s267.beta.photobucket.com/user/OkdF/media/Mitsu_Evo9_grpN_Dyno-1_zps3780d166.jpg.html?sort=3&o=1)

Max rengas teho = max power from the wheels
Max moottori teho = max power from the engine
Max momentti = max torque
Max nopeus = max speed
Ilmapaine = atmospheric pressure
Lämpötila = temperature

OldF
yes at the dynoplots you posted the boost pressure drops very quickly,this is not good if you want to gain significant power,and torque for enough rpms.Basically to make comments at a dynoplot we have to know some other things like,the afr ratio(air to fuel ratio) from 2000rpms to red line,the advance,and a diagramm with the boost curve to rpms.
These dynoplots are not so good for the ammount of boost pressure for an evo 9.Little power gains(360bhp) and little torque(460nm) for the first dynoplot.Here in Greece good mappers with 1,6 bar of boost(ct) can extract more than 400bhp and about 530-550nm.But again as i said we have to know all the engine parameters to comment safely.The boost is a lot for just 360 bhp.You can have 360 bhp with less boost,and thats only good.
Second dynoplot is strange because while this evo 9 has plenty of torque,has very little power gains.Something is wrong.

See here an evo 9 with Motec ecu+exhaust+cams 272 degrees.Watch how the maximum power curve goes after 6500rpms,and compare with yours dynoplots
Watch the torque line how drops slowly,with result to can keep maximum torque between 3500rpms to 5500rpms.To have this result you have to keep boost pressure as high as you can(not only boost,but other parameters too)
This evo the boost pressure is 1,8 bar overboost with 1,5 bar ct.

http://img823.imageshack.us/img823/1248/evo8komando.jpg

So for resume,we can t have conclusions when just pub talking and say that this car has 2 bar,but other car has 2,5 bar.Maybe the car with 2,5 bar is not faster even if they are same cars/engines.
Also we have to define which boost we mean,overboost at midrange rpms,or the ct boost pressure at upper rpms.

Anothervery important point is the air fuel ratio(afr) and the advance timing degrees.We can have same engine with ie 2,0 bar overboost and 1,6 ct.We programm the engine ecu at 11,4 afr and 13 advance degrees= ie 400 bhp and 500nm torque.
we reprogramm now the same engine with SAME boost but now with 12,2 afr and 16 degrees advance=440bhp and 570nm torque.
Thats why when you dont know all the parameters you can t have any conclusions for any engine/car output.We can comment,but not an conclusion.

[dimviii]

I have always wondered how other Mitsubishi did their anti-lag as compared to the "rocket" system that Prodrive used. For that matter how do the modern systems from vw Citroen and ford work?

(really loving the technical discussion, is there any way to start another thread about it so we don't anger brother John and lose all this great info?)

each wrc car has its own design antilag system.Maybe they seem to be same,but they have plenty of difference between them.
Its not safe to comment when we don t know how it works.The Subaru rocket system was a very different one created by prodrive.

[br21]

Just few my comments to this very interesting discussion.
- about anti-lag in wrc cars - it's very complex thing, this Subaru/Prodrive "rocket" system was very unique, we once had S12 turbo but it was almost impossible to make it work good without Prodrive ECU and anit-lag mapping
- about power/torque differences - my experience shows that almost all rally cars from Finland (or Estonia) we were working with had smaller amounts of hp/Nm, at least on the paper comparing to the cars from Western/South Europe. Also at the same time almost all those cars were better balanced with better traction... so maybe it's some kind of different approach of the car builders, etc.

[Franky]

Please go back to this thread. It's about the VW wrc car.

Separate the posts regarding all the technical aspects into a new thread instead, so they could continue discussion over there.

[worldrallynews]

I have a question to the engineers:

Can someone explain this two springs in the same shock?

IMG

Edit: Unfortunately I can´t post photos or links until I reach 15 posts.

In VW Motorsport official website, there´s a Polo R WRC photo gallery, taken in studio, and one of its photographs was taken from the front naked brake disk and shock/spring. I´m curious to know why in the same shock there are 2 different springs, the black one appearing to be stiffer than the top red one. Does ne1 has any clues on this suspension setup?

[OldF]

Okay I start a new Thread with the name "Tech rallycar stuff". :idea:
I can still change the name later.

Thanks.

[Brother John]

Here is the thread for fans of technology, turbo boost and more of rally cars. Have fun.

Rally Cars tech stuff http://www.motorsportforums.com/images/smilies/spanner.gif

[dimviii]

I have a question to the engineers:

Can someone explain this two springs in the same shock?

IMG

Edit: Unfortunately I can´t post photos or links until I reach 15 posts.

In VW Motorsport official website, there´s a Polo R WRC photo gallery, taken in studio, and one of its photographs was taken from the front naked brake disk and shock/spring. I´m curious to know why in the same shock there are 2 different springs, the black one appearing to be stiffer than the top red one. Does ne1 has any clues on this suspension setup?

Tender Springs vs. Helper Springs (http://www.e30m3project.com/e30m3performance/tech_articles/susp-tech/springs/index.htm)

A helper spring is used to keep the main spring tight between the perches when the suspension is at full droop. It "helps" keep the main spring snug, if you will. A helper spring has a very soft rate, on the order of 10 lbs/in. It's just strong enough to push the main spring up against the upper spring perch, but that's about it.

[OldF]

Second dynoplot is strange because while this evo 9 has plenty of torque,has very little power gains.Something is wrong.

Did you notice that it’s a grp N (32 mm restrictor) dyno chart?


we reprogramm now the same engine with SAME boost but now with 12,2 afr and 16 degrees advance=440bhp and 570nm torque.

What is typical air to fuel ratio range for an evo9 grp N? Do you know the Brake Specific Fuel Consumption (BSFC) for an evo9 grp N?

Btw, the turbo used in WRC and WTCC is a Garrett GTR2560R (http://www.gikturbo.com/performance/turbochargers/wrc-garrett-motorsport/garrett-gtr2560r.html). I asked them for some information about the turbo but the replay was:
- Sold only for cars homologated with that turbo.
- No information available.

[dimviii]

Did you notice that it’s a grp N (32 mm restrictor) dyno chart?.

No didn t noticed it :dozey: Thought that it was like the previous link with the road evo dynoplot.My bad.




What is typical air to fuel ratio range for an evo9 grp N? Do you know the Brake Specific Fuel Consumption (BSFC) for an evo9 grp N?
No i dont know,but do we need it?


Btw, the turbo used in WRC and WTCC is a Garrett GTR2560R (http://www.gikturbo.com/performance/turbochargers/wrc-garrett-motorsport/garrett-gtr2560r.html). I asked them for some information about the turbo but the replay was:
- Sold only for cars homologated with that turbo.
- No information available.

yes they dont give outside information for motorsport products,specially when fresh launched at world motorsport scene.Garrett did the same also with TR30R used at 2,0 lit wrc cars,as the IHI RX 6 for Subaru wrc cars.

But you can try for info this company,maybe you are lucky.
Owen Developments - turbo, turbos, turbochargers, performance tuning and engineering (http://www.owendevelopments.co.uk/)

[worldrallynews]

A helper spring is used to keep the main spring tight between the perches when the suspension is at full droop. It "helps" keep the main spring snug, if you will. A helper spring has a very soft rate, on the order of 10 lbs/in. It's just strong enough to push the main spring up against the upper spring perch, but that's about it.

Thank you!

[cali]

Guys, It's a brilliant topic! I'm learning with every post. Keep up the good work, as I will not contribute here anything due to my lack of knowledge. But it is sure fun to read about it.

[stefanvv]

Polo's aerodynamics explained - Rally the World | Volkswagen and the Polo R WRC - rallytheworld.com (http://www.rallytheworld.com/en/#rally-the-world-tech-talk/content)

[OldF]

This excellent post by Zico deserves to be here. :up: It's from a thread ”two step launch” few years back.



Where are you Zico?


http://www.motorsportforums.com/wrc/130159-2-step-launch.html#post553319

[Coach 2]

3093

Maybe more over-boost than ct-pressure dimviii?

[FliegenderZirkus]

Hello everyone, I hope my first post will be in the correct thread... I was wondering about manufacturers switching from mechanical to electric water (coolant) pumps, which seems to be the trend for the future (despite many problems with them in the past). From what I found so far they are used in Peugeot 207 S2000 and in Mini John Cooper Works WRC & S2000 1.6T. Do you know of other rallye cars using electric water pumps? And what is so fragile about them that they caused many drivers retire from events (e.g. Václav Pech in Barum Czech Rally 2012 lately)? I suspect that the manufacturers mostly use the pumps you can find in BMWs (in E90 etc.), which should be pretty reliable. By the way, are the homologation documents with detailed specifications available to the public? Thank you for any replies!

[br21]

I think there are many reasons for electric water pumps. They do not use engine power (like auxiliary belt run water pumps do), smaller risk of them not working (when the belt broke), you can position the pump where you want (weight distribution, etc.), you can easier bleed the system (run the pump before the engine starts), let the pump work after turning off the engine, etc. In S2000 car it might be also problematic to use belt run pump because of very high engine revs?
At the beginning there were a lot of problems with electric water pumps, but now I think they are pretty reliable.
There is also electric water pump in Fiesta S2000 and it's also based on some BMW pump.

[FliegenderZirkus]

Thank you for the answer and tip on Fiesta S2000, I didn't know about that one. The advantages of electric pumps seem to be clear indeed, I think we will see more of them in the close future. What I would actually be interested in are details about how the temperature control is implemented etc., but such information is pretty secret, I can imagine. Or is there just a regular thermostat on the bypass hose of the radiator and the rpm of the pump is kept constant? That is probably not the way BMW does it...well if anyone has a tip where to look I will certainly appreciate it. :)

[br21]

I don't know exactly how it is done, but I will find out, no problem! There sure is no such thing like thermostat. There is only Engine Coolant Temperature sensor which gives data to the ECU and it controls the pump.

[dimviii]

for sure no thermostat,as the pump pulley is not working when engine is cold.

[br21]

ECU controls the flow of the pump using coolant temperature sensor, engine load, revs, etc. So sometimes pump is not working at all, sometimes with very high revs. On WOT water pump stops, cooling fans stop, alternator also. It's quite complex thing in S2000 car.

[Co-driven]

I think that probably this is the best topic to post this doubt I have regarding homologations.

How do they work? For example, for a certain car there's a certain brand of dampers homologated? Or any damper with the dimensions and characteristics can be used?

And what all those variant mean (VO, VK, etc...)?

[bubbaontour]

for sure no thermostat,as the pump pulley is not working when engine is cold.

you sure.....

[dimviii]

you sure.....

haven t see such a system,but as the ecu controls the pump speed,can t find a reason for working pump at cold engine.
except if it turns the pulley slowly just to prevent from extreme heating near cylinder head? and after a point of degrees ie 70 c turns faster?

[br21]

you sure.....

yes, I'm 100% sure. there are moments when pump is not working at all, for example after engine start in cold conditions, then as dimviii says it starts to work really slowly and then "normally". also on WOT it stops for short periods of time.

[Viking]

All we will ask for is 400k :)

How to build a World Rally Championship car | Pole Position - YouTube (http://www.youtube.com/watch?v=sKneZuyNSG4)

[OldF]

I think that probably this is the best topic to post this doubt I have regarding homologations.

How do they work? For example, for a certain car there's a certain brand of dampers homologated? Or any damper with the dimensions and characteristics can be used?

And what all those variant mean (VO, VK, etc...)?

A car has a basic group A homlogation where the cars dimensions, weight and all those parts which must be original in group A (e.g. intake manifold, exhaust manifold etc.) are described. By a VO (Variant Option) a manufacturer homologate the parts that are allowed to be homologated in the groups A and N and modified parts in the other groups (R, S2000 & WRC). VO is also used when a modified part replaces the previous one. VK is a kit which includes all the parts homologated for use in rallying. ER (erratum) is used when there is an error in previous homologation. ER is also used when homologating modifications to the engine. Little easier to homologate only the modification and not the whole engine for every modification.


Parts that must be homologated varies in different groups. For example dampers are free in groups A and N but but must be homologated in the other groups.


Everything begins with a group A homologation. In group N there is a complementary homologation form where are all the parts that must be original in group N but didin't had to be original in group A. All the other parts allowed to be homologated in group N (brakes, clutch etc.) are homologated with a VO.


In the other groups (R, S2000 & WRC) the basic rallying parts are homologated in a VK and all the modifications with a VO or ER.


The explanations for the other ones you can find here (http://www.fia.com/sites/default/files/regulation/file/251%20(2013).pdf)


Homologations you can find here (http://www.fia.com/sites/default/files/regulation/file/ToutesVoitures_2013.pdf)


R1A/B = VR1A/B, R2B/C = VR2B/C, R3C = VR3C, R3T = VR3T, R3D = VR3D, S2000 = KSR (VK-S2000 rallyes or SUPER 2000 1.6 turbo), WR = WRC parts (bigger rear wing, fly wheel etc.)


Here (http://www.ralliart.com/eGRN/index_eR4.html) you can find homologation forms for different Mitsubishi evolutions. Citroen used to have the homologation forms for the C2 R2 on their web site but they're not there anymore.


Hope this help and hope I got it all right. :)

[OldF]

ECU controls the flow of the pump using coolant temperature sensor, engine load, revs, etc. So sometimes pump is not working at all, sometimes with very high revs. On WOT water pump stops, cooling fans stop, alternator also. It's quite complex thing in S2000 car.

What is WOT?
Alternator stops, why?

[OldF]

haven t see such a system,but as the ecu controls the pump speed,can t find a reason for working pump at cold engine.
except if it turns the pulley slowly just to prevent from extreme heating near cylinder head? and after a point of degrees ie 70 c turns faster?

I think that is the idea to have few more horsepowers. The pump is operating only when necessary.

[TyPat107]

yes, I'm 100% sure. there are moments when pump is not working at all, for example after engine start in cold conditions, then as dimviii says it starts to work really slowly and then "normally". also on WOT it stops for short periods of time.

If I remember correctly bubba is a mechanic for the mini wrc, so now I am really intrigued why he asked that.

[dimviii]

What is WOT?
Alternator stops, why?

wot=wide open throttle(butterfly at intake)
alternator =few more power due to less friction at alternator.

[Co-driven]

A car has a basic group A homlogation where the cars dimensions, weight and all those parts which must be original in group A (e.g. intake manifold, exhaust manifold etc.) are described. By a VO (Variant Option) a manufacturer homologate the parts that are allowed to be homologated in the groups A and N and modified parts in the other groups (R, S2000 & WRC). VO is also used when a modified part replaces the previous one. VK is a kit which includes all the parts homologated for use in rallying. ER (erratum) is used when there is an error in previous homologation. ER is also used when homologating modifications to the engine. Little easier to homologate only the modification and not the whole engine for every modification.


Parts that must be homologated varies in different groups. For example dampers are free in groups A and N but but must be homologated in the other groups.


Everything begins with a group A homologation. In group N there is a complementary homologation form where are all the parts that must be original in group N but didin't had to be original in group A. All the other parts allowed to be homologated in group N (brakes, clutch etc.) are homologated with a VO.


In the other groups (R, S2000 & WRC) the basic rallying parts are homologated in a VK and all the modifications with a VO or ER.


The explanations for the other ones you can find here (http://www.fia.com/sites/default/files/regulation/file/251%20(2013).pdf)


Homologations you can find here (http://www.fia.com/sites/default/files/regulation/file/ToutesVoitures_2013.pdf)


R1A/B = VR1A/B, R2B/C = VR2B/C, R3C = VR3C, R3T = VR3T, R3D = VR3D, S2000 = KSR (VK-S2000 rallyes or SUPER 2000 1.6 turbo), WR = WRC parts (bigger rear wing, fly wheel etc.)


Here (http://www.ralliart.com/eGRN/index_eR4.html) you can find homologation forms for different Mitsubishi evolutions. Citroen used to have the homologation forms for the C2 R2 on their web site but they're not there anymore.


Hope this help and hope I got it all right. :)


Thank you very much for your answers!

[OldF]

wot=wide open throttle(butterfly at intake)
alternator =few more power due to less friction at alternator.

Thanks Dimviii!

[bubbaontour]

ok.... thats great when its going flat out.. we have these big things called road sections on rallys and we do use interior heaters. what happens then???

[bubbaontour]

haven t see such a system,but as the ecu controls the pump speed,can t find a reason for working pump at cold engine.
except if it turns the pulley slowly just to prevent from extreme heating near cylinder head? and after a point of degrees ie 70 c turns faster?

Ok, we use interior heaters on cold rallys.. there are long slow road sections...

[br21]

Ok, we use interior heaters on cold rallys.. there are long slow road sections...

on cold rallies we use heaters also, but water temp have to raise a little bit to make it heating.
in "normal" conditions we use only blower, rarely even no blower.

[bubbaontour]

on cold rallies we use heaters also, but water temp have to raise a little bit to make it heating.
in "normal" conditions we use only blower, rarely even no blower.

If you turn the pump off because the engine water is cold whats going to happen to the heater?? also how are you going to control the circulation between the rad and the heater circuit?

[br21]

If you turn the pump off because the engine water is cold whats going to happen to the heater?? also how are you going to control the circulation between the rad and the heater circuit?

of course the pump is not stopped for minutes, or sth. just some seconds, so no such problems as above.

[Donalduck]

Doesnt the WRCars have electric heaters? Just wondering?

[br21]

Doesnt the WRCars have electric heaters? Just wondering?

WRC I don't know, but I don't think so...
S2000 have simple heater (which uses coolant fluid) plus simple blower.

[Donalduck]

haven t see such a system,but as the ecu controls the pump speed,can t find a reason for working pump at cold engine.
except if it turns the pulley slowly just to prevent from extreme heating near cylinder head? and after a point of degrees ie 70 c turns faster?

Some modern road cars have two different cooling systems on the engine. so they can have different temperature on the cylinder head than the cylinders. They also use electric pumps controlled by the ECU (pwm signal).

[dimviii]

Some modern road cars have two different cooling systems on the engine. so they can have different temperature on the cylinder head than the cylinders. They also use electric pumps controlled by the ECU (pwm signal).

which cars?

[Donalduck]

Volkswagen,Audi and Skoda. Newest generation engines.

[dimviii]

Volkswagen,Audi and Skoda. Newest generation engines.

which engines?

[Donalduck]

which engines?

Several petrol engines in the new Golf MK7. The 1.4 122bhp engine used in the Golf MK6 have a an own cooling system for the intercooler, which is integrated in the intake manifoil.

[dimviii]

Several petrol engines in the new Golf MK7. The 1.4 122bhp engine used in the Golf MK6 have a an own cooling system for the intercooler, which is integrated in the intake manifoil.

water through intercooler at tsi 1,6 engine?

[Donalduck]

water through intercooler at tsi 1,6 engine?

No.

[dimviii]

no what?

[Donalduck]

no what?

Just no!! Whats your point in these endless questions?

[dimviii]

Just no!! Whats your point in these endless questions?
do you want to ask all the members if anybody have understood YOUR answers? are you scared by questions,or you pay per post?

[Donalduck]

do you want to ask all the members if anybody have understood YOUR answers? are you scared by questions,or you pay per post?

Yes i am scared by your questions!! i probably wont get any sleep tonight. Damn you!

[dimviii]

Yes i am scared by your questions!! i probably wont get any sleep tonight. Damn you!
so how much you pay per word?
here everybody wants to know something he dont know or understant.If you dont bother to explain,dont waste this topic please.

[makinen_fan]

I found the above a bit interesting as a mechanical engineer myself and after a bit of google search I came across this:
Dual-circuit cooling system for SSP 491 Audi 1.4l TFSI Engine With Dual Charging (http://www.scribd.com/doc/101571874/20/Dual-circuit-cooling-system)
(Scroll to page 31)
From what the document says it is used in 1.4l 136kW TFSI and 1.2l TFSI Engine from Audi.

[dimviii]

thanks makinen fan!

[Mirek]

Just a tiny point. If I'm not mistaken the 1.2 TSI engine is product of Škoda supplied to other brands of VAG.

[FliegenderZirkus]

What an interesting and informative discussion! I'll try to sum up what I found so far about the topic
...I was wondering about manufacturers switching from mechanical to electric water (coolant) pumps...
All of the previously mentioned cars, namely Peugeot 207 S2000, Ford Fiesta S2000, and MINI John Cooper Works 1.6T 2000 (not sure about WRC) use electric water pumps produced by Pierburg (=KSPG), to be exact the model CWA200, which can be found in many BMWs produced since 2004 under different part numbers such as 11 51 7586925 or 11 51 7604027, depending on the motor model (M54, N52, N53, N54, N55 among others). I haven't found how sophisticated control of the pumps in rallye application is, but you can find how BMW does it here on page 75 (add the www, I can't send links yet):
.1addicts.com/forums/attachment.php?attachmentid=586998&d=1317333814
So to me it seems like there IS a thermostat, but it's a somehow electronically controlled one plus the revolutions of the pump are controlled as well. Again, I didn't find how rallye cars do it.
Apparently there is a new model of Pierburg pumps called CWA400, which according to its name and the following plot should be about twice as powerfull: 3103. But as of now I wasn't able to find any production vehicle or motorsport car using it. Only this article mentiones several high-performance cars premiering 2013 and possibly using it (add http):
://presse-center.kspg.de/no_cache/en/press-kits/pm-single/article/sieben-top-ten-motoren-fahren-mit-kspg.html
I also wasn't able to find the relationship between Pierburg and Continental who also produce electric water pumps and call them Smart coolant pump. Sometimes I found contradictory information about which car uses which, such as here:
.conti-online.com/generator/www/com/en/continental/pressportal/themes/press_releases/3_automotive_group/powertrain/press_releases/pr_2013_01_16_best_engines_en.html
where both Pierburg and Continental claim that the new BMW 135is 3.0L uses their pump...well they are similar indeed, but can it be some sort of a cooperation? Anyway I hope this post wasn't completely uninteresting and thank you for comments.

[Mirek]

It might be possible that BMW uses Pierburg and Continental ones for different markets. I admit I have no clue about that but I can see it as a possibility.

[A FONDO]

I want to raise a question about that dreadful understeering the Polo gets when entering corners. Where it comes from - is it a construction defect in the chassis? If yes - when they can homologate a new one? If no - which components of the transmission they can improve and which are from supplier?

[dimviii]

I want to raise a question about that dreadful understeering the Polo gets when entering corners. Where it comes from - is it a construction defect in the chassis? If yes - when they can homologate a new one? If no - which components of the transmission they can improve and which are from supplier?

understeer can create just suspension,suspension+allignment,front diff settings+suspension,or with a little help from driving style,or some combinations of themAlso you can have understeer from wrong balance between from front/rear suspension.No understeer can t be created from chassis,maybe from a wrong mounted engine(just beside the bumper like subarus) but again there are solutions to ''hide'' it,but not to reset completely

[Mirek]

I think that is very hard to answer without being an insider. I'm no expert at all but in my opinion some understeering is natural for all AWD cars without central differential. If You watch closely You can see it present with all current WRC/S2000 cars (I started to notice that when first Peugeot and than Škoda found centre diff useless and stopped using it). You can play with diffs, geometry, weight balance (not much under current rules), suspension etc. but for me it remains a question what works the best with these cars. In the ideal world You prefer neutral handling but look at Loeb, he is much more understeering than most of others and he is mostly faster.

[makinen_fan]

understeer can create just suspension,suspension+allignment,front diff settings+suspension,or with a little help from driving style,or some combinations of them.No understeer can t be created from chassis,maybe from a wrong mounted engine(just beside the bumper like subarus) but again there are solutions to avoid it.

Also weight distribution and how the weight shifts under braking also has a significant role to play in this. And weight distribution is a fundamental property from the chassis, if they got it wrong initially there is no way around it but just to compensate through suspension/diff setup.

[Mirek]

Most of the current cars are basically same in their general layout. The difference in weight balance can't be so significant like when we compare for example Impreza and Lancer or even more when we compare Quattro and 205 T16. Chassis are very similar, engines of same kind mounted in same locations, rollacages almost same, bodyshell panels are also made almost same way. What playes a more role is sure the weight shifting from suspension and geometry layout.

[stefanvv]

I think that is very hard to answer without being an insider. I'm no expert at all but in my opinion some understeering is natural for all AWD cars without central differential. If You watch closely You can see it present with all current WRC/S2000 cars (I started to notice that when first Peugeot and than Škoda found centre diff useless and stopped using it). You can play with diffs, geometry, weight balance (not much under current rules), suspension etc. but for me it remains a question what works the best with these cars. In the ideal world You prefer neutral handling but look at Loeb, he is much more understeering than most of others and he is mostly faster.

This is characteristic of all 4 wheel drive cars. The first Quattro which had central diff were understeering alot also. The S1 evolution was improvement by shortening the wheelbase and also taking weight in front and placing it weigth to the back like oil coolers.

[Mirek]

The main reason why Quattro was so badly understeering was its heavy longitudinal engine in front of the front axle.

[dimviii]

Also weight distribution and how the weight shifts under braking also has a significant role to play in this. And weight distribution is a fundamental property from the chassis, if they got it wrong initially there is no way around it but just to compensate through suspension/diff setup.

weight distribution yes,thats whu i said from a wrong mounted engine=very front mounted at subarus.
chassis ONLY ,can t have a wrong weight distribution,the wrong weight distribution will be if you mount at wrong places all the rest pieces.

[stefanvv]

The main reason why Quattro was so badly understeering was its heavy longitudinal engine in front of the front axle.

True, anyway non 4wd car can oversteer like rwd car

[dimviii]

True, anyway non 4wd car can oversteer like rwd car
to oversteer like a rwd is not correct for a 4wd,but you can have oversteer character very easy in a right designed 4wd car.Evos with some tweeks at electronic center diff,and rear alignement can oversteer quite like rwd.

[makinen_fan]

weight distribution yes,thats whu i said from a wrong mounted engine=very front mounted at subarus.
chassis ONLY ,can t have a wrong weight distribution,the wrong weight distribution will be if you mount at wrong places all the rest pieces.

yes that's right in that chassis only cannot have any significant difference. By chassis I interpret it the chassis itself plus body, roll cage engine placing etc.

Mirek you are right that there should not be significant difference in WD, but you never know. From my work experience with F1 cars, the engineers are VERY sensitive about tiny changes in WD, not sure about rally cars though. I believe no where near, I would say that changes in +/- 2% would not make much difference. Do you or anyone know approx values for S2000 cars out of interest?

[TyPat107]

Wasn't the focus Wrc supposed to be 50/50 distribution? I thought I remember them making a big deal of that.

I am intrigued that the idea of the center differential is worthless. Being from the US and not having wrc/s2000 cars we are most familiar with subarus, and the shops that prepare subarus claim the center differential is the most important. Just wondering why the difference in philosophy?

[Rallyper]

Maybe a bit off-topic, but: BMW X-drive system starts from rear and moves to front axle when frontwheels are starting to slip. Makes the car always steering without understear. Maybe not comparable to WRC/WRC2, but I like it very much myself on wintery small road nearby my home....

[stefanvv]

Maybe a bit off-topic, but: BMW X-drive system starts from rear and moves to front axle when frontwheels are starting to slip. Makes the car always steering without understear. Maybe not comparable to WRC/WRC2, but I like it very much myself on wintery small road nearby my home....

It is the same with the newest Quattro technology. I don't think it is possible in Rally cars without central diff and electronics, but I'm not that familiar anyway. Let the experts tell.

[Mirek]

Maybe a bit off-topic, but: BMW X-drive system starts from rear and moves to front axle when frontwheels are starting to slip. Makes the car always steering without understear. Maybe not comparable to WRC/WRC2, but I like it very much myself on wintery small road nearby my home....

I think that no carmaker has yet found a non-permanent 4WD system useful for competitions but that's partly because of the rules. Where rules allow hi-tech stuff it might be different. Just one example. My brother was heavily involved in SAE Formula competition (worldwide university cup for small combustion and electric formula cars). The best electric car of all (from Dutch University of Delft) uses full-active 4WD system with four small but powerful engines mounted in wheel hubs. Each engine has maximum output around 30 kW but weights only 4 kg. Maximum allowed power available from batteries is 85 kW so that there is plenty of space to play with torque distribution. But here we speak about car which weights only 170 kg (its power make it able to do 0-100 km/h in 2,5 secs)...

[Mirek]

Mirek you are right that there should not be significant difference in WD, but you never know. From my work experience with F1 cars, the engineers are VERY sensitive about tiny changes in WD, not sure about rally cars though. I believe no where near, I would say that changes in +/- 2% would not make much difference. Do you or anyone know approx values for S2000 cars out of interest?

Of course there are differences but I doubt You can see them by eye on the video as was pointed at the start of this discussion. I bet what is possible to see comes much more from suspension, diff setup, geometry etc. while the differences given by bodyshell and it's weigh distribution although sure important for the very best performance must be marginal or impossible to see for outside observer. Currently used cars are too similar to each other...


I have no values, sorry. I'm just writing what comes to my mind ;)

[Mirek]

Wasn't the focus Wrc supposed to be 50/50 distribution? I thought I remember them making a big deal of that.

Probably it was. With rules of 2.0 WRC cars it was possible to achieve that. But it's not everything. You know dumbbell has also 50/50 weight distribution but an awful moment of inertia :) That was the case of Audi Quattro. The S1 had perfect 50/50 weight balance but most of the mass was in front of front axle and to compensate it another big mass was at the back. That's what makes the car slow and hard to turn. The 205 T16 had awful weight balance but it was very nimble as most of the weight was concentrated close to the center of gravity between axles. If I remember right with Focus they tried to make also the center of gravity as low as possible and also the ideal balance by putting the spare wheel behind the rear axle under the floor (among other things). That's what goes against the previous point. I remember Pentti Airikkala was a loud critic of the Ford solution here on the forum.


I am intrigued that the idea of the center differential is worthless. Being from the US and not having wrc/s2000 cars we are most familiar with subarus, and the shops that prepare subarus claim the center differential is the most important. Just wondering why the difference in philosophy?

It is the most important if it is active one like in Subarus and Mitsubishis or even more sophisticated like in old WRC cars. But when You are limited to simple clutchpacks or other dumb mechanical things it's all different. With the S2000 they first use center diff - for example Abarth had it. Peugeot discovered that it brings very little advantage but serious disadvantages - car was heavier with it (in that time S2000 rules allowed cars to be only 1100 kg heavy and nobody was able to achieve the limit) and it consumed power. Especially the second point was very valid because the S2000 with just naturally aspirated engines were a bit underpowered. The problem of releasing rear axle when using handbrake was solved by a clutch in rear diff body. I am pretty sure Škoda largely tested both variants - with and without center diff and decided to go Peugeot way although with different supplier (X-Trac instead of Sadev). Abarth later switched for X-Trac system without center diff too. Later when rules for 1.6T cars were created they decided to ban the center diff at all.

[A FONDO]

understeer can create just suspension,suspension+allignment,front diff settings+suspension,or with a little help from driving style,or some combinations of themAlso you can have understeer from wrong balance between from front/rear suspension.No understeer can t be created from chassis,maybe from a wrong mounted engine(just beside the bumper like subarus) but again there are solutions to ''hide'' it,but not to reset completely
As makinen_fan explained, in chassis I meant the hardware you can't change in a few minutes. If it was suspension and diff preload, VW would have easily done it as they did so many thousands of test kilometers with factory drivers and engineers. Even we fans here saw that problem from short clips some months ago. Maybe this is why VW had been so conservative about their future performance in real competition. Note that masking "chassis" problem with various small setup tweaks conflicts with drivers' driving style and harms their ultimate confidence.

So I want to repeat the question, when VW is allowed to introduce (homologate) big changes?

[dimviii]

yes that's right in that chassis only cannot have any significant difference. By chassis I interpret it the chassis itself plus body, roll cage engine placing etc.

Mirek you are right that there should not be significant difference in WD, but you never know. From my work experience with F1 cars, the engineers are VERY sensitive about tiny changes in WD, not sure about rally cars though. I believe no where near, I would say that changes in +/- 2% would not make much difference. Do you or anyone know approx values for S2000 cars out of interest?

also at wrc are sensitive about wd front -rear and left-right.

[dimviii]

As makinen_fan explained, in chassis I meant the hardware you can't change in a few minutes. If it was suspension and diff preload, VW would have easily done it as they did so many thousands of test kilometers with factory drivers and engineers. Even we fans here saw that problem from short clips some months ago. Maybe this is why VW had been so conservative about their future performance in real competition. Note that masking "chassis" problem with various small setup tweaks conflicts with drivers' driving style and harms their ultimate confidence.

So I want to repeat the question, when VW is allowed to introduce (homologate) big changes?

Slowson maybe driver liked the slight understeer of polo,is not bad thing when driver can pushes with this.Also dont take Latvalas words by rule,he has setup problems for many years.Its better to see Ogier,or he has a different chassis?

[RS]

Just a tiny point. If I'm not mistaken the 1.2 TSI engine is product of Škoda supplied to other brands of VAG.

Yes it is.

"Old" chain driven 1.2TSI was designed and manufactured by Skoda, new belt driven 1.2TSI is also produced by Skoda but I don't know whether it was developed by them too.

[A FONDO]

Slowson maybe driver liked the slight understeer of polo,is not bad thing when driver can pushes with this.Also dont take Latvalas words by rule,he has setup problems for many years.Its better to see Ogier,or he has a different chassis?

No, it was Capito or some other chief saying that, not Latvala.

And I dont think Ogier set that understeer on purpose. In Monte it was making him so angry that he was applying the exit-throttle so early. There was a perfect clip (I should have mentioned it back then :( ) showing a tight corner where the two Polos almost stalled versus all the Citroens smooth as trains on rails. Also the flatout clip from Sweden you posted - I know Ogier and JML are not the tidiest drivers but they threw the rear so early while everybody else including Neuville Novikov etc were smooth and clean. But lets better wait for typical dusty events.

[Munkvy]

I think that no carmaker has yet found a non-permanent 4WD system useful for competitions but that's partly because of the rules.

The Nissan R32 GTR's ATTESSA system also ran in RWD initially, moving forward based on wheel slip and G forces. This was very effective in Group A touring cars, with the rules being changed in both Japan and Australia to effectively outlaw 4WD as it had such a significant advantage. The idea of it of course was to help on turn in/mid corner, without the front diff causing understeer, then on throttle application the 4WD kicked in, allowing full grip on corner exit.

As a road car it made for a quite tail happy drive as the sensors were a bit slow to react (this improved considerably in later models). However I don't think it would be much use on loose surfaces.

Active Centre diffs in production cars such as late model Subarus and Mitsubishis and then the ultimate in the WRC 2L formula of course were the evolution of this. But they add a lot of complexity and cost... I believe most modern cars with a performance 4WD setup would have some form of electronic adjustment?

[OldF]

In the book I have about suspension etc, there's a summary what cause different behaviours of a car.
Some of the below are obvious and others apply better to a formula racer but I listed all of them.


Understeer:


Rear anti-roll-bar too soft.
Front anti-roll-bar too stiff.
Toe-in too big.
Wrong camber angle (usually too positive at the front and too negative at the rear.
Front tyre pressure too low.
Rear tyre pressure too high.
Too soft tyre compound at the rear.
Too hard tyre compound at the front.
Too little down force at the front.
Too much downforce at the rear.
Too much weight at the front.


Here (http://www.awdwiki.com/en/home/) is an web site about AWD / 4WD systems and different makes AWD / 4WD systems.

[makinen_fan]

Racing engine technology artcile on Ford Fiesta WRC engine
Race Engine Technology - Dec/Jan 2012 (http://content.yudu.com/Library/A1wvd5/RaceEngineTechnology/resources/19.htm)
Highly recommended article for anyone interested engine technology

[Racing Ka]

Racing engine technology artcile on Ford Fiesta WRC engine
Race Engine Technology - Dec/Jan 2012 (http://content.yudu.com/Library/A1wvd5/RaceEngineTechnology/resources/19.htm)
Highly recommended article for anyone interested engine technology

Automotive porn

[Zico]

Does anyone know if any of the current WRC cars use any form of TVC (Torque vectoring control)? Obviously front and rear active diffs were banned a couple of years ago but would the simpler, slightly less effective systems that simply brake individual wheels (limiting torque transfer to around 50%) as used on some the latest road cars be legal ?

I'd be interested to know the actual wording of the FIA's ban on these devices if anyone has any ideas on where to find it.

Some articles on the subject:

Torque-ing up for the corners - Torque Vectoring Control - Cars Bikes Trucks (http://www.cbt.com.my/2012/07/30/focus-on-road-holding/)

Torque Vectoring and Active Differential (http://torque-vectoring.belisso.com/)

[Mirek]

In my opinion they don't use it.

[dimviii]

they use electronics and sensors so they cant be used.

[makinen_fan]

Dimvi, am i correct to assume that brakes are kept purely mechanical without any form of electronic support?

[br21]

Dimvi, am i correct to assume that brakes are kept purely mechanical without any form of electronic support?

exactly, only two pumps - one for front, one for rear, plus handbrake pump... everything purely mechanical.

[Co-driven]

Is there any specific item on the FIA regulations (including regional championships) that won't enable a car with lower cubic capacity to run in a 'bigger' class.

For example: a R2 car run in the R3 class.

[Mirek]

R2 and R3 are not classes. One is class 5 and the other class 6. And I think it is not possible because if You enter wrong class the stewards of the meeting will put You in the correct one during scrutineering. Classes are no longer created purely according to the engine capacity.

[Co-driven]

R2 and R3 are not classes. One is class 5 and the other class 6. And I think it is not possible because if You enter wrong class the stewards of the meeting will put You in the correct one during scrutineering. Classes are no longer created purely according to the engine capacity.

Thanks for the answer.

But in a hypothetical situation, a driver can enter in, for example, Class 3 with a Class 6? Or stewards aren't going to allow it?

[br21]

somebody here asked some time ago about weight distribution of S2000 car.
it's around 360 kgs each front wheel, 320kgs each rear wheel, with crew, spare wheel and some fuel

[OldF]

Racing engine technology artcile on Ford Fiesta WRC engine
Race Engine Technology - Dec/Jan 2012 (http://content.yudu.com/Library/A1wvd5/RaceEngineTechnology/resources/19.htm)
Highly recommended article for anyone interested engine technology

Hard to believe that M-Sport would reveal such detailed information about the engine.

Interesting reading, especially the section about the development of the DI engine. By this (http://www1.eere.energy.gov/vehiclesandfuels/pdfs/merit_review_2011/adv_combustion/ace065_rinkevich_2011_o.pdf#23) 30 million $ is used for the development of the Ford EcoBoost engine.

Referring to the few examples below both power and torque increases of a DI engine with the same or even less fuel (= air) consumption but that doesn't seems to be the case with the WRC cars. Can someone explain why?

“Mercedes-Benz is introducing new V6 and V8 gasoline direct injection engines for the CL and S Class that increase output by as much as 12.5% and decrease gasoline consumption by as much as 24%.”

“The design highlights of the 3.5-liter V6 in the S 350 BlueEFFICIENCY include a completely new air intake and exhaust system in conjunction with a variable resonance intake manifold and optimized inflow and backflow. Result: with the same displacement, the output compared with the previous 200 kW (272 hp) model rose by 12.5% to 225 kW (306 hp), while maximum torque has increased by 5.7 percent to 370 N·m (273 lb-ft) (predecessor: 350 N·m) and now is available over a broad engine speed range from 3500 to 5250 rpm.”

Green Car Congress: New Gasoline Direct Injection Engines in Mercedes-Benz CL- and S-Class Vehicles Cut Fuel Consumption By Up to 24%, Increase Output by Up to 12.5% (http://www.greencarcongress.com/2010/09/bluedirect-20100907.html)

“Cadillac sells the CTS with both indirect and direct injection versions of its 3.6 liter V6 engine. The indirect engine produces 263 horsepower and 253 lb-ft of torque, while the direct version develop 304 hp and 274 lb-ft. Despite the additional power, EPA fuel economy estimates for the direct injection engine are 1 MPG higher in the city (18 MPG vs 17 MPG) and equal on the highway.”

Direct fuel injection - What it is, how it works - Direct fuel injection (http://cars.about.com/od/thingsyouneedtoknow/a/directinjection.htm)

“The advantage of direct injection is a more efficient engine. For example, Hyundai claims its 2.4 Theta II GDI gets 7 to 12 percent better torque than an equivalent port injection engine, while at the same time getting 10 percent better fuel economy.”

“The engine makes 198 horsepower and 184 pound-feet of torque. The current, port-injected 2.4-liter engine in the Sonata makes only 175 horsepower and 168 pound-feet of torque.”

Hyundai increases power, fuel economy with direct injection | The Car Tech blog - CNET Reviews (http://reviews.cnet.com/8301-13746_7-10399881-48.html)

[Mirek]

I'm no expert but in my opinion the biggest advantage of DI is that it allows the engine to run with high air-fuel ratio. That is good for the economy under low load but not that useful for racing engine where for maximum output You need richer AFR. I guess DI is somewhat more effective for WRC engine as well but I have no idea how much compared to usual way. Maybe Dimviii or someone else can educate us?

[OldF]

It would indeed be intresting to get an explanation to the engine issue.


The WRC and S2000 cars have and R5 will have three-way damapers (adjustable slow & fast compression + adjustable rebound). I don’t know if it’s the regulations that says that the dampers have to be three-way dampers or isn’t there any need for slow & fast rebound?

In the previous issue of “Vauhdin Maailma” JML told that the VW is more sensitive to changes in the set-up. As an example he said that with Ford he could do quirte a lot of “clicks” to the dampers before he could feel the difference.

Here (http://www.penskeshocks.co.uk/downloads/AdjustableTechManual.pdf) is a link to a pdf which explains very nicely how the fast & slow compression and rebound works (8760 series beginning on page 11). I had been looking for this kind of explanation (words + pics) for a long time. :)

Btw, for newcomers. Here (http://www.motorsportforums.com/wrc/141848-hello-antony-warmbold.html) is the link to Antony Warmbold’s thread. In the first post a link to his blog with lot of interesting readings.

[br21]

The WRC and S2000 cars have and R5 will have three-way damapers (adjustable slow & fast compression + adjustable rebound). I don’t know if it’s the regulations that says that the dampers have to be three-way dampers or isn’t there any need for slow & fast rebound?


there is no such rule, that only 3 adjustments are allowed. but those are most important ones so most widely used. now there are a lot of dampers with additional - fourth adjustment - hydraulic bumpstop. most widely used is rubber bumpstop, then there is hydraulic bumpstop not adjustable and hydraulic bumpstop which is adjustable, it's common in Sachs or BOS dampers.
So called "fast rebound" is not separately adjustable by a knob, it's often done by system like RCV (Reiger) or CAS (BOS) - when wheel is not touching the ground rebound "opens" fully and wheel is free to go down and touch the road again, it's good thing, but sometimes makes some trouble. Similar with for example Reiger CCV system - corner control valve - during cornering system detects which wheel is outer one and stiffens it's slow compression, giving less roll in the corner - it allows to use softer ARBs.

[Coach 2]

The problem is to create the smallest possible droplets, preferably gas before combustion begins. There is also a problem to create as equal mixture as possible in the combustion chamber. These are the problems one solve better with DI engine. (I think). These benefits should also prevails in a WRC engine.

Hope no one that really understand this, tear off his hair because of this explanation.

[Coach 2]

So called "fast rebound" is not separately adjustable by a knob, it's often done by system like RCV (Reiger) or CAS (BOS) - when wheel is not touching the ground rebound "opens" fully and wheel is free to go down and touch the road again, it's good thing, but sometimes makes some trouble.


As far as I know, you can adjust drop-out with how much / little pressure one has before it triggers. Tein works this way in any case. Normally, a pressure of about 140 kg (or less) will be required before the drop-out occurs. This means that drop-out first occurs when the pressure is below 140 kg.

[AMSS]

As far as I know, you can adjust drop-out with how much / little pressure one has before it triggers. Tein works this way in any case. Normally, a pressure of about 140 kg (or less) will be required before the drop-out occurs. This means that drop-out first occurs when the pressure is below 140 kg.

That is correct (if you`re reffering to RCV or CAS or whatever they name it) mostly they are spring load adjustable when the rebound needle opens, this is done in the topmount with a very small diameter spring able to withold a certain weight, by changing the spring rate you can adjust how soon/late the rebound needle opens!
And actually the rebound doesn`t really open fully, it`s more less a certain amount/velocity of oil to run pass the shimstacks, for really fast damper speeds this small hole want be enough so something is always limited by the shimming!

[br21]

That is correct (if you`re reffering to RCV or CAS or whatever they name it) mostly they are spring load adjustable when the rebound needle opens, this is done in the topmount with a very small diameter spring able to withold a certain weight, by changing the spring rate you can adjust how soon/late the rebound needle opens!
And actually the rebound doesn`t really open fully, it`s more less a certain amount/velocity of oil to run pass the shimstacks, for really fast damper speeds this small hole want be enough so something is always limited by the shimming!

yes, yes of course you are right, it was just shortcut in my thinking :)

[dimviii]

I'm no expert but in my opinion the biggest advantage of DI is that it allows the engine to run with high air-fuel ratio. That is good for the economy under low load but not that useful for racing engine where for maximum output You need richer AFR. I guess DI is somewhat more effective for WRC engine as well but I have no idea how much compared to usual way. Maybe Dimviii or someone else can educate us?

the resume is that with direct injection you have more horsepower because you can control better the air-fuel ratio.
You can control better the timing of injection and the amount of fuel,due to the position of injector inside the combustion chamber.

[TyPat107]

Dimviii, why does DI accommodate higher compression ratios with higher boost? Is it just the control over the air fuel ratio?

[dimviii]

Dimviii, why does DI accommodate higher compression ratios with higher boost? Is it just the control over the air fuel ratio?

allows higher compression ratios because it is prone to less detonation.

[Coach 2]

allows higher compression ratios because it is prone to less detonation.

Think you are very close to the main issue here, to avoid detonating when trying to create an explosion.Pressure changes the gas to be liquefied, or drops. Heat changes liqued back into gas.This happens in the intake manifold, intake channels and inside the engine several times in a four stroke engine. A DI engine does not take account of this issue in the intake section of the engine, but can concentrate on getting the most air to enter. Currently, this is the best way to achieve what we think is the best ratio of air and gasoline (14.5 to 1).

Again, hope whoever understands this on a different level, do not tear off his hair.

[dimviii]

Think you are very close to the main issue here, to avoid detonating when trying to create an explosion.Pressure changes the gas to be liquefied, or drops. Heat changes liqued back into gas.This happens in the intake manifold, intake channels and inside the engine several times in a four stroke engine. A DI engine does not take account of this issue in the intake section of the engine, but can concentrate on getting the most air to enter. Currently, this is the best way to achieve what we think is the best ratio of air and gasoline (14.5 to 1).

Again, hope whoever understands this on a different level, do not tear off his hair.

your english are much better to explain proper such tech points.
At fuel injected engines most lean we manage with race fuel is no more than 12,2-12,4 to 1.
to understant the difference a Mitsu evo 9 with 11.8 to 1 with an identical evo with 12,2 to 1, if we accelerate from 30km/h to 220km/h the evo with 12,2 to 1, will be about 3-4 car lengths ahead.
These air fuel mixtures(12,2 to 1) are not safe at all with fuels we use (and can find at petrol stations) at our daily cars.Case of time to break.
In my daily evo i use lean mixtures of 11,9-12 to 1 but i have some gauges to monitor detonation.

[AMSS]

WHat compression ratio do they actually use in the 1,6 DI engines? I heard from one guy what he said Ford uses but couldn`t believe it was true..

[dimviii]

WHat compression ratio do they actually use in the 1,6 DI engines? I heard from one guy what he said Ford uses but couldn`t believe it was true..

so what did you heard? 11?

[OldF]

By the regulations the max. compression ratio is 12,5:1.

[AMSS]

By the regulations the max. compression ratio is 12,5:1.

Than what I heard was bogus, must have been the "calculated" (boost included) CR

[OldF]

So I want to repeat the question, when VW is allowed to introduce (homologate) big changes?

Three years before any major changes to the car. VO, ER etc. homologations possible.

“The rules state that you should be driving the same car three years and we're going through the last season now and VW the first season.”

Google Translate (http://translate.google.com/translate?sl=fi&tl=en&js=n&prev=_t&hl=en&ie=UTF-8&eotf=1&u=http%3A%2F%2Fwww.mtv3.fi%2Furheilu%2Fralli%2Fuut iset.shtml%2F2013%2F03%2F1727598%2Fhirvonen-paljastaa-citroen-pienissa-ongelmissa)

[OldF]

Does anybody know if the “gear changing” light is at red limit or is it at revs (plus gear changing delay) that gives the best torque to the drive shafts for the next gear compared to previous?

[dimviii]

the red light is not at limiter but some hundrets rpms before limiter.

[OldF]

So, it doesn’t have anything to do with the optimum torque from wheels?

[dimviii]

So, it doesn’t have anything to do with the optimum torque from wheels?

explain please,torque is from engine.

[TyPat107]

Oldf means the red light flashes at the point when max torque is measured at the wheels in relation to engine rpm.

For example if peak torque is reached at 5200 rpm and rev limit is 7500, does the shift light flash at 5200, 5500, 7000, or 7500 rpm?

If I am understanding correctly...

[OldF]

Thanks Typath107,

It’s sometimes difficult to explain technical things in English when it’s not your native language. :confused:

That’s what I tried to explain. Engine torque is of course always the same on same revs but the revs on which the max torque is on the wheels, depends of the ratio of the gearbox / final ratio.

Current gear ratio divided by next gear ratio times peak engine torque revs (For example 2nd gear ratio / 3rd gear ratio * engine peak torque revs).

[Mirek]

What You need is to use biggest possible power all the time through the gear. Torque is a value which is good for understanding the engine characteristics but it's often wrongly interpreted because it changes through gear ratios as You said. Power keeps same through gears (except some looses of course). Basically if You have any of the two curves You don't need the other. It's much simpler to understand the engine from power curve in my opinion because peak power is always the best You can get while peak torque not.

You shall shift the way You have always the biggest possible area under the power curve through rpm range You use. For example You have an engine which has peak torque at 4000 rpm but peak power at 8000 rpm. For best performance You shall stay around the 8000. Where You would shift up depends on the shape of power curve but it will be somewhat after peak power.

[OldF]

For example You have an engine which has peak torque at 4000 rpm but peak power at 8000 rpm. For best performance You shall stay around the 8000. Where You would shift up depends on the shape of power curve but it will be somewhat after peak power.

That’s correct. The torque at the drive shafts is highest (with the correct gear) when the power from the engine is around peak power.

I made few years back some calculations to see how it looks on a graph. The Mitsu example is not the best one because the peak torque is little below 3300 rpm and peak power is already at 3600 rpm. The Subaru has the peak torque at 3500 rpm and peak power at 4400 rpm.

Mitsu
http://i267.photobucket.com/albums/ii284/OkdF/MitsuEvo9torquecurvesondifferentgears_zps746b0df7. jpg

Subaru
http://i267.photobucket.com/albums/ii284/OkdF/Subarutorquecurvesondifferentgears_zps5b522695.jpg

[OldF]

The so called "soft" anti-lag system of R5 cars means that all fuel must go through combustion chamber.

With a little googling I found three different ALS systems.



Air bypassing the throttle body to the intake manifold. Fuel from the fuel injectors and retarded ignition. [/*:m:2mmy6vq0]
Air directly to the exhaust manifold. Fuel from the fuel injectors and retarded ignition. [/*:m:2mmy6vq0]
Both air and fuel directly to the exhaust manifold and retarded ignition. [/*:m:2mmy6vq0]

I assume that it is the last one used by WRC cars (and the loudest one), or is it?

[Mirek]

I wrote that post bad, sorry. It shall be that with R5 all the air must go through combustion chamber (and if I understand right it must go through throttle as well) not directly to the exhaust. The fuel as well must be supplied from engine fuel injectors. I don't know if WRC cars have fuel injection into exhaust but sure they have air supply line to the exhaust.

I'm no expert in this...

[danon]

https://www.youtube.com/watch?v=wyJn40ExwZY

[danon]

https://www.youtube.com/watch?v=5g6cHs5vMRE

[TyPat107]

Very good write up of the Subaru "rocket" anti lag system.
Beyond the Dyno: External Combustion Rocket Anti Lag System + JDM Spec C Impreza STI (http://www.motoiq.com/MagazineArticles/ID/2771/External-Combustion-Rocket-Anti-Lag-System-JDM-Spec-C-Impreza-STI.aspx)

[br21]

Very nice article and videos!

[OldF]

Also I found it interesting in last nights review when he (RK) commented how easier is to drive the Fiesta compared to the DS3!


Tomáš Kostka and I believe also Thierry Neuville said the same - that Fiesta is easy to drive and very forgiving car while DS3 is very sharp car which punishes every mistake.


Mads has said the Ford and Citroen are completely different to set up, and to drive, and that he is changing his style to suite the car, and to learn from experience within the team.

What could be the difference between Citroen and Ford? I would imagine that the springs, dampers, anti-roll bars, diffs and camber could have same set-up, stiffness etc. so the difference between the cars must be in the basic design (geometry) of the suspension in spite of simple regulations. At least Ford have more positive caster compared to Citroen.

Mikko once said that the design approach of Citroen is different but he did not won’t to go into details. JML said in “Vauhdin Maailma” that the body shell of the Fiesta moves/rolls more compared to the Polo and that the Polo is more sensitive to changes in the set-up. Juho commented in an interview that he start to feel sick because the Ford swings so much.

[stefanvv]

Also I found it interesting in last nights review when he (RK) commented how easier is to drive the Fiesta compared to the DS3!


Tomáš Kostka and I believe also Thierry Neuville said the same - that Fiesta is easy to drive and very forgiving car while DS3 is very sharp car which punishes every mistake.


Mads has said the Ford and Citroen are completely different to set up, and to drive, and that he is changing his style to suite the car, and to learn from experience within the team.

What could be the difference between Citroen and Ford? I would imagine that the springs, dampers, anti-roll bars, diffs and camber could have same set-up, stiffness etc. so the difference between the cars must be in the basic design (geometry) of the suspension in spite of simple regulations. At least Ford have more positive caster compared to Citroen.

Mikko once said that the design approach of Citroen is different but he did not won’t to go into details. JML said in “Vauhdin Maailma” that the body shell of the Fiesta moves/rolls more compared to the Polo and that the Polo is more sensitive to changes in the set-up. Juho commented in an interview that he start to feel sick because the Ford swings so much.
I think the most noticable difference is suspension travel, it looks much more at Fiesta (Polo too). So generally speaking DS3 looks much more "stiffer", imo more difficult to handle and looks like more prone to understeer, while Fiesta seems to be more driver friendly as he can throw it all the way round.
Another noticable difference looks suspension geometry. I noticed only on Polo rear shock's angle is opposite to front ones, it looks like it is designed for heavy breaking on front and hard acceleration with more downforce on the rear (probably this helps for not so much understeer, asuming overall setup is same for every car), because of this geometry. this could be the whole difference in car handling in corners.
It is also possible I just talk rubbish... :)

[Mirek]

Shock absorber top mounting points, i.e. the angle of the shocks on Polo is taken from Fabia S2000. VW admitted that openly. Nevertheless I believe the overall suspension travel of Polo is bigger than of Fabia. VW commented that the limit for suspension travel was in reliability of driveshaft joints under such extreme angles. The main reason why shocks are placed under such angle is to make them longer. M-Sport made them parallel like // while Škoda opposite like A. It's interesting that 208 R5 has them placed in Fiesta style //. The negative thing of the long travel is massive changes of geometry in extreme suspension situations as simple McPherson struts suffer a lot from this phenomena. There are also much higher forces in steering with the big castor angle. Visible body movement of Fiesta can hardly help overall performance, at least I can not imagine how. Maybe it helps the feeling of the driver, I don't know. Despite that all I believe the main difference between Citroën and Ford is in differential settings. In times of C4 WRC they even used 40/60 torque split on asphalt.

[Rallyper]

My thinking only:
Stiffer bodyshell same as stiffer springs, which is not good at icy or snowy surfaces. Longer suspention travel has nothing to do when there´s tarmac.
Back in the time driving my Ascona with stiff suspension and absolutely no grip on winterconditions was no good at all ( and that was in rdinary traffic going to the annual inspection of authorithies).
Back then I learned that smother suspention was a better thing in winthertimes even in raceconditions. Having said that it was on roads that wasn´t on tarmac.

[stefanvv]

Stiffer suspension and overall setup are better on asphalt, yeah CMR 2005 was my teacher several years ago :D

[AMSS]

Hi
Some points regarding bodyshell and wheel geometry.
A stiffer bodyshell is almost always an advantage, in general the stiffer bodyshell the softer and more precise all wheel setups will be and also alot more sensible to fine adjustments. It`s almost impossible or very difficult to use the chassis softness as an advantage. Think of it: how can you adjust the chassis stiffness.

[Rallyper]

Hi
Some points regarding bodyshell and wheel geometry.
A stiffer bodyshell is almost always an advantage, in general the stiffer bodyshell the softer and more precise all wheel setups will be and also alot more sensible to fine adjustments. It`s almost impossible or very difficult to use the chassis softness as an advantage. Think of it: how can you adjust the chassis stiffness.

For sure. I didn´t mean stiffer bodyshell would be bad. Just that in very slushy conditions you really can tell what a stiff suspension can do to the handling, when as i RMC, you have tyres that are not apropriate to the weather conditions...

[br21]

for some years now M-Sport cars were designed with more body roll than other cars. it's because of mounting points of the suspension, but also because of softer springs, dampers, etc.

[AMSS]

True, but after NORF pre event test last year they visibly stiffened the setup on the cars based on drivers demands, and the results were instantly better as well..

[makinen_fan]

for some years now M-Sport cars were designed with more body roll than other cars. it's because of mounting points of the suspension, but also because of softer springs, dampers, etc.

I think suspension mounting points would have to be more associate with body pitch than roll. Body roll is controlled by spring rate, ride height and antiroll bars. But the pitch has a lot to do also with suspension geometry and anti-dive characteristics induced in wheel kinematics (i.e. wheel moving backwards/forwards as it moves up/down).

Also I am not sure if this was the case with Focus vs C4. I remember C4 being softer generally than the Focus, especially diving under breaking.

[Plan9]

Have M-Sport developed a Fiesta R5+? If so, what is the main its main point of difference from the R5?

[Mirek]

Have M-Sport developed a Fiesta R5+? If so, what is the main its main point of difference from the R5?

What it shall be? There is 3 years long homologation cycle for R5 cars. They can not come with some big changes in such short time period. If You speak about FIA events...

[stefanvv]

There is R5+ already for British championship I presume, Wilson junior tested it last year on some event. Probably he meant that, yes it is developed, but I have no idea will be used by someone. Concerning differences, I think it had bigger restrictor and 6 speed gearbox AFAIR.

[br21]

R5+ is something similar to S2400, I mean planned for promotion/national events, etc. R5+ kit contains bigger turbo, bigger restrictor, etc. M-Sport plan to have conversion kits available for customers, but AFAIK those kits are not ready yet.

[Juha_Koo]

True, but after NORF pre event test last year they visibly stiffened the setup on the cars based on drivers demands, and the results were instantly better as well..

I'm really waiting for Mexico (and especially Portugal) to see Mikko's speed on gravel... Interesting to see whether he'll use the new stiffer setups or go back to his old ones.

Focus was supersoft, I remember one corner combination over crest and through a dip in certain testroad. In 2010 Focus bottomed basically every time (the plastic/carbon fibre piece behind front wheel arc was destroyed during the day) through that corner/dip. A year later Fiesta seemed to be a bit harder as it didn't bottom out on any of the runs I spectated there. Corner here in 1:58: http://www.youtube.com/watch?v=VWTIxREKX-M#t=119 (usually the line was a bit more from inside). Compare with Focus: http://juhake.kapsi.fi/JML_Day2/album/ 6th and 7th picture.

[Mirek]

There is R5+ already for British championship I presume, Wilson junior tested it last year on some event. Probably he meant that, yes it is developed, but I have no idea will be used by someone. Concerning differences, I think it had bigger restrictor and 6 speed gearbox AFAIR.

R5+ is something similar to S2400, I mean planned for promotion/national events, etc. R5+ kit contains bigger turbo, bigger restrictor, etc. M-Sport plan to have conversion kits available for customers, but AFAIK those kits are not ready yet.

Thanks You both.

[OldF]

R5+ is something similar to S2400, I mean planned for promotion/national events, etc.

Or MW lobbying FIA. “Look what we have made. Wouldn’t this be nice for the next WRC formula (because we can build it)”. ;)

http://www.m-sport.co.uk/m-sport-news/f ... odels.html (http://www.m-sport.co.uk/m-sport-news/fiesta-r5/impressive-debut-for-m-sport-s-latest-models.html)

“Based on the standard Ford Fiesta R5 which launched earlier this year, the Fiesta R5+ incorporates a modified turbo and air-intake system. The standard 32mm restrictor has also been replaced with a 34mm example which provides the engine with an extra 30hp. Not homologated for FIA championships, the Fiesta R5+ is intended for national series.”

Few videos.
http://www.youtube.com/watch?v=o0yGUSNYeE0
http://www.youtube.com/watch?v=hGcJbJHItAI
http://www.youtube.com/watch?v=LN_Kxy4HX18

[OldF]

On a Finnish forum a forum member told that his brother has modified a group N Mitsu to the Finnish FIR R 4WD group regulations. With E85 fuel and 34 mm restrictor (otherwise 35 mm). Dyno results with 1,5 bar boost, 375 PS / 720 Nm.

[stefanvv]

R5+ is something similar to S2400, I mean planned for promotion/national events, etc.

Or MW lobbying FIA. “Look what we have made. Wouldn’t this be nice for the next WRC formula (because we can build it)”. ;)

http://www.m-sport.co.uk/m-sport-news/f ... odels.html (http://www.m-sport.co.uk/m-sport-news/fiesta-r5/impressive-debut-for-m-sport-s-latest-models.html)

“Based on the standard Ford Fiesta R5 which launched earlier this year, the Fiesta R5+ incorporates a modified turbo and air-intake system. The standard 32mm restrictor has also been replaced with a 34mm example which provides the engine with an extra 30hp. Not homologated for FIA championships, the Fiesta R5+ is intended for national series.”

Few videos.
http://www.youtube.com/watch?v=o0yGUSNYeE0
http://www.youtube.com/watch?v=hGcJbJHItAI
http://www.youtube.com/watch?v=LN_Kxy4HX18
Definitelly more powerful than regular R5. In hands of more capable drivers, this will be very exciting car to watch. I like these experiments M-Sport are making with bigger engines. It'll be a shame if those cars will never be used.

[stefanvv]

On a Finnish forum a forum member told that his brother has modified a group N Mitsu to the Finnish FIR R 4WD group regulations. With E85 fuel and 34 mm restrictor (otherwise 35 mm). Dyno results with 1,5 bar boost, 375 PS / 720 Nm.
Here in Bulgaria we used to have 2 drivers driving ethanol Mitsus before 2013. They beated all S2000 on regular bases, even our multi-champion Iliev, but some crashes prevented better results.

[Mirek]

It sounds quite possible. Some time a go one engineer told me that for gr.N Impreza with 33 mm restrictor a proper E85 set engine meant something like +40 Hp and +60 Nm compared to usual racing petrol one.

[TyPat107]

It sounds quite possible. Some time a go one engineer told me that for gr.N Impreza with 33 mm restrictor a proper E85 set engine meant something like +40 Hp and +60 Nm compared to usual racing petrol one.

Is there any concern about running out of fuel at the end a group of stages since more fuel is required? Also are teams there buying e85 or mixing their own? And if mixing, are using regular petrol from a pump or race fuel?

[Mirek]

It was with a car from Belgian championship, I don't know exact regulations for the fuel - if they use their own or how it is. In the national championship I think the risk of running out of fuel isn't that big as the loops aren't that long but anyway he told me the consumption was some 20% higher.

[stefanvv]

Probably bigger tank goes with the engine pack

[TyPat107]

Probably bigger tank goes with the engine pack

Is tank size not regulated? Even with our open rules here, capacity must be no greater than stock.

[stefanvv]

Probably bigger tank goes with the engine pack

Is tank size not regulated? Even with our open rules here, capacity must be no greater than stock.
May be it is, no idea. But in that case stock trunk should be enough to supply E85 cars for longer passes.

[dupanton]

It was with a car from Belgian championship, I don't know exact regulations for the fuel - if they use their own or how it is. In the national championship I think the risk of running out of fuel isn't that big as the loops aren't that long but anyway he told me the consumption was some 20% higher.

In the Belgian Championship it isn't allowed any more, in the Netherlands it is used a lot in Nissan 350Z's and Evo R4/N4's.

[OldF]

Interesting pics of the Skoda Fabia S2000 powertrain and chassis.

http://new.skoda-auto.com/en/motorsport/cars

Looking at the second pic from left, the attachment points of the suspension arms to the upright/wheel hub are at very low point. Must have something to do with the suspension geometry. Is this a tarmac suspension? Looks like it would be very vulnerable on gravel.

Fuel consumption 0,60 l / km SS (60 l / 100 SS km)

[makinen_fan]

Really good find! Nice details in the photos.

You are right about the suspension arms attachment with the upright, they seem to be unnecessarily low but they should have their purpose. Surprisingly, it seems it can accommodate even longer shock absorbers (at least at the rear).

[janvanvurpa]

Interesting pics of the Skoda Fabia S2000 powertrain and chassis.

http://new.skoda-auto.com/en/motorsport/cars

Looking at the second pic from left, the attachment points of the suspension arms to the upright/wheel hub are at very low point. Must have something to do with the suspension geometry. Is this a tarmac suspension? Looks like it would be very vulnerable on gravel.

Fuel consumption 0,60 l / km SS (60 l / 100 SS km)

Yeah that's clearly a thing to correct roll center when they go low for tarmac...
Lovely detailed piccies, wish we could find equally nice picces of the other cars..

[OldF]

Yeah that's clearly a thing to correct roll center when they go low for tarmac...
Lovely detailed piccies, wish we could find equally nice picces of the other cars..

Thanks vurpan, you have earned your Kossu.;)

Sometimes Google give some answers. The third pic is the answer.

http://www.meganracing.com/tech/faqs.asp?id=106&subject=Suspension

[janvanvurpa]

Thanks vurpan, you have earned your Kossu.;)

Sometimes Google give some answers. The third pic is the answer.

http://www.meganracing.com/tech/faqs.asp?id=106&subject=Suspension

Kiitos Gamle Finne..you know I manufacture suspension mainly gravel but in America every boy under 30 has compulive disorder which makes the feel they have to lower their car 100-120mm so their car is like this, so I have made things like that to correct the position of lower arm when using short strut.


http://www.meganracing.com/uploadimage/dpage/2102011_174138.jpg

Very hard to deal with silly boys who have mental disorders. Facts don't help, reasoning, drawings, nothing helps..

Sometimes to help understand I use teacher's aids like this:
First you point out the components or idea:
http://www.rallyrace.net/jvab/spgm/gal/Volvo/Mentoring1.jpg

Then you impress on them how important the idea is...

http://www.rallyrace.net/jvab/spgm/gal/Volvo/Mentoring2.jpg

with rally boys it usually takes a couple of times: (especially when they are "injur-near" and their name was originally "Håkansson" before it became "Hawkinson" and then I ''döpte om dom'' to Hoikansainalainen ---all rally drivers must have a Finnish name to channel to spirit)

That's me doing the technical instruction....over here i"m one of the "Old FARTs" (Flemish-American Rally Team)

[Rallyper]

Kiitos Gamle Finne..you know I manufacture suspension mainly gravel but in America every boy under 30 has compulive disorder which makes the feel they have to lower their car 100-120mm so their car is like this, so I have made things like that to correct the position of lower arm when using short strut.


http://www.meganracing.com/uploadimage/dpage/2102011_174138.jpg

Very hard to deal with silly boys who have mental disorders. Facts don't help, reasoning, drawings, nothing helps..

Sometimes to help understand I use teacher's aids like this:
First you point out the components or idea:
http://www.rallyrace.net/jvab/spgm/gal/Volvo/Mentoring1.jpg

Then you impress on them how important the idea is...

http://www.rallyrace.net/jvab/spgm/gal/Volvo/Mentoring2.jpg

with rally boys it usually takes a couple of times: (especially when they are "injur-near" and their name was originally "Håkansson" before it became "Hawkinson" and then I ''döpte om dom'' to Hoikansainalainen ---all rally drivers must have a Finnish name to channel to spirit)

That's me doing the technical instruction....over here i"m one of the "Old FARTs" (Flemish-American Rally Team)

So that´s Your Ecellency "i egen hög person" in the picture, trying to learn out some behaviour?

[janvanvurpa]

So that´s Your Ecellency "i egen hög person" in the picture, trying to learn out some behaviour?

Jo, erkänner.

To keep this to rally car tech stuff here is us installing nice B23 turbo motor for our 2wd turbo class into that nice 240... Nobody pushes Volvo 240 harder in America (which is a bit odd for a Ford guy, eller hur?)
(Sanningen är vi fick aldrig Escorten dvs rwd Escorten härborta, så 240 är Americas Escort, men större så det passar våra SS som är ofta som Autobahn)


We bad. way bad
(I'm the old guy with his ciggie...maybe 5 years ago.)

http://www.rallyrace.net/jvab/spgm/gal/Volvo/volvoduds2.jpg

One of ''our'' version of Sierra in backgrunden (came with a Ford 2300SOHC nearly identical to Volvo B23 but all IRON!

[Rallyper]

So cool! More Volvo-fans here in Sweden should know about your work over there. As you probably already know there´s a lot of turbo-240/740/940´s here, rebuilt by youngsters with power train illness...

[Gregor-y]

Most 240s that aren't rusted to heck seem to be in the Northwest of the country. I had a coworker defect to work for Case IH in Portland who says they're everywhere. I'd consider getting one myself but this Subaru just won't die.

And in regards to those Skoda pictures (fifth from the left), are those ball bearings on the wheels? Most stuff (okay, my Subaru again) uses needle bearings, though it does look like the rally car's got two rows of sealed ball bearings, like a skateboard.

[OldF]

Kiitos Gamle Finne..you know I manufacture suspension mainly gravel but in America every boy under 30 has compulive disorder which makes the feel they have to lower their car 100-120mm so their car is like this, so I have made things like that to correct the position of lower arm when using short strut.


http://www.meganracing.com/uploadimage/dpage/2102011_174138.jpg

Very hard to deal with silly boys who have mental disorders. Facts don't help, reasoning, drawings, nothing helps..

Sometimes to help understand I use teacher's aids like this:
First you point out the components or idea:
http://www.rallyrace.net/jvab/spgm/gal/Volvo/Mentoring1.jpg

Then you impress on them how important the idea is...

http://www.rallyrace.net/jvab/spgm/gal/Volvo/Mentoring2.jpg

with rally boys it usually takes a couple of times: (especially when they are "injur-near" and their name was originally "Håkansson" before it became "Hawkinson" and then I ''döpte om dom'' to Hoikansainalainen ---all rally drivers must have a Finnish name to channel to spirit)

That's me doing the technical instruction....over here i"m one of the "Old FARTs" (Flemish-American Rally Team)

Is that the motivational method or ”banging the information into the head :arrows:” method?

[gorganl2000]

Kiitos Gamle Finne..you know I manufacture suspension mainly gravel but in America every boy under 30 has compulive disorder which makes the feel they have to lower their car 100-120mm so their car is like this, so I have made things like that to correct the position of lower arm when using short strut.

Very hard to deal with silly boys who have mental disorders. Facts don't help, reasoning, drawings, nothing helps..

Sometimes to help understand I use teacher's aids like this:
First you point out the components or idea:
http://www.rallyrace.net/jvab/spgm/gal/Volvo/Mentoring1.jpg

Then you impress on them how important the idea is...

http://www.rallyrace.net/jvab/spgm/gal/Volvo/Mentoring2.jpg

with rally boys it usually takes a couple of times: (especially when they are "injur-near" and their name was originally "Håkansson" before it became "Hawkinson" and then I ''döpte om dom'' to Hoikansainalainen ---all rally drivers must have a Finnish name to channel to spirit)

That's me doing the technical instruction....over here i"m one of the "Old FARTs" (Flemish-American Rally Team)

i truly appreciate your approach to passing on knowledge...lol

[OldF]

In the beginning I was a little bit sceptical about the power, torque and bmep figures given in the article below. I found some equations using bmep so I decided to give it a try. I was little surprised how close the results are calculated with different equations. If the data in the article is not correct it’s at least consistent.:)


http://content.yudu.com/Library/A1wvd5/RaceEngineTechnology/resources/19.htm

BMEP = break mean effective pressure
http://www.epi-eng.com/piston_engine_technology/bmep_performance_yardstick.htm
“The definition of BMEP is: the average (mean) pressure which, if imposed on the pistons uniformly from the top to the bottom of each power stroke, would produce the measured (brake) power output.
Note that BMEP is purely theoretical and has nothing to do with actual cylinder pressures. It is simply a tool to evaluate the efficiency of a given engine at producing torque from a given displacement.”

The coefficient 0,0001424 I use in the calculations is derived from the equation Power = torque * omega.
Omega = 2 * pii * f (1/s)
Power = Watt
Torque = Nm

Omega -> rpm = 2*pii*rpm/60 = 2*pii/60 = 0,1047
Watt -> Power (PS) = Watt * 1,35962152 / 1000 = 0,001360

Coefficient = 0,1047 * 0,001360 = 0,0001424

The three equations I use are:
Power (PS) = Torque (Nm) * rpm * 0,0001424
BMEP (N/m2) = P (W) * nc / V (m3) * N (1/s) nc = 2 for a 4-stroke engine.
BMEP (N/m2) = 4 * π * T (Nm) / V (m3)

Ford Focus WRC

Data from the article:
348 bhp = 1,014 * 348 = 353 PS
353 PS @ 6500 rpm
680 Nm @ 3000 rpm
bmep @ peak power = 24 bar = 2,4 N/mm2 = 2 400 000 N/ m2
Bore = 84,8 mm
Stroke = 88 mm

Cylinder / piston area = 5 647,83 mm2
Average radius of crank shaft turn = 0,02817 m

Torque at peak power

P (PS) = T (Nm) * rpm * 0,0001424 => T = P / rpm * 0,0001424 = 353 / 6500 * 0,0001424 = 381,4 Nm

Calculating with bmep.
T (N/m) = BMEP (N/m2) * V (m3) / 4 * π = 2400000 * 0,001998 / 4 * 3,14 = 381,6 Nm

Calculating with bmep and cylinder / piston area
F = pressure (N/mm2) * area (mm2) = 2,4 * 5647,83 = 13 555 N
T = F * Average radius of crank shaft turn = 13555 * 0,02817 = 381,8 Nm

Bmep at peak torque
BMEP (N/m2) = 4 * π * T (Nm) / V (m3) = 4 * 3,14 * 680 / 0,001998 = 4 274 675 N/m2 / 100 000 = 42,7 bar

Power at peak torque
P (W) = BMEP (N/m2) * V (m3) * N (1/s) / nc ( nc for a 4-stroke engine is 2)
P = 4274675 * 0,001998 * (3000/60) / 2 = 213 520 W / 1000 = 213,52 kW * 1,3596 = 290,3 PS

P (PS) = T (Nm) * rpm * 0,0001424 = 680 * 3000 * 0,0001424 = 290,5 PS

Ford Fiesta WRC

Data from the article:
Bmep @ peak power = 29,3 bar 2,93 N/mm2 = 2 930 000 N/ m2
325 bhp @ 6250 rpm = 1,014 * 325 = 330 PS (329,6 with one decima)
Bore = 83 mm
Stroke = 73,9 mm

Cylinder / piston area = 5410,61 mm2
Average radius of crank shaft turn = 0,02365 m

Torque at peak power

T @ peak power = 330 / 6250 * 0,0001424 = 371 Nm (370,8 with one decimal)

Calculating with bmep.
T (N/m) = BMEP (N/m2) * V (m3) / 4 * π = 2930000 * 0,0016 / 4 * 3,14 = 373 Nm

Calculating with bmep and cylinder / piston area
F = pressure (N/mm2) * area (mm2) = 2,93 * 5410,61 = 15 853 N
T = F * Average radius of crank shaft turn = 15853 * 0,02365 = 375 Nm

Peak power

Using the torque calculated with bmep, 373 Nm
P (PS) = T (Nm) * rpm * 0,0001424 = 373 * 6250 * 0,0001424 = 332 PS

Calculating with bmep, 29,3 bar
P (W) = BMEP (N/m2) * V (m3) * N (1/s) / nc ( nc for a 4-stroke engine is 2)
P = 2 930 000 * 0,0016 * (6250/60) / 2 = 244 167 W / 1000 = 244,17 kW * 1,3596 = 332 PS

Another way to estimate the power of the Fiesta WRC

In the article is said that on a typical rally stage the fuel consumption for the Fiesta WRC is about 0,7 l/km.

On the Skoda’s web page (http://new.skoda-auto.com/en/motorsport/cars) the fuel consumption is 0,6 l/ SS km for the S2000.

The Fiesta consume 0,7 / 0,6 = 1,17 (17%) more fuel on a special stage. As I don’t know the power of the Skoda S2000 I have to make different estimates. What I’ve found out a turbo engine use a richer fuel to air ratio but as I don’t know the AF ratio I have to guess what it is. If a turbo engine use a AF of 12:1 and a NA engine 13:1, the NA engine need only about 92% of fuel compared to a turbo engine to produce the same power.
Skoda 300 PS => Fiesta = 0,92 * 1,17 * 300 = 323 PS
Skoda 305 PS => Fiesta = 0,92 * 1,17 * 305 = 328 PS
Skoda 310 PS => Fiesta = 0,92 * 1,17 *310 = 334 PS
Skoda 315 PS = > Fiesta 0,92 * 1,17 * 315 = 339 PS

By the previous calculations 328-334 PS seems to be closer to the “truth”.:)

[Mirek]

Sorry for uneducated answer (moreover I have no time now).

The torque values doesn't fit. Fiesta WRC definitely has much more torque than Fiesta R5 (cca 400 Nm). Old 2.0 litre WRC had huge torque. Even old Fabia WRC with really bad engine in terms of torque had 640 Nm. The latest cars had something between 800-900 Nm @ cca 2000 rpm in my opinion. I think that the problem is in turbo pressure.

With fuel consumption it doesn't make sense because turbo cars have anti-lag (pure waste of fuel). 70 l/100 km seems to be really low figure but maybe with direct injection it is possible. On the other hand there is no direct injection in Fabia S2000 so even without ALS it's not comparable. I'm no expert at all.

[br21]

now engines both in r5 or wrc, so with direct injection, are using much less fuel than previous rally turbo engines, like in 2.0l WRC cars or GpN cars.
for example fiesta s2000 was using some 70l/100km ss, and R5 uses around 60l/100km ss, but it also depends on stage characteristics, etc.

[OldF]

I'm no expert at all.

Me neither, I just put numbers into the equations and see what happens.


Sorry for uneducated answer

What do you mean by this?:confused:



AS I said, if the data in the article is not correct it’s at least consistent. 680 Nm seems low in my opinion also if a N4 evo has above 600 Nm with a lot lower boost and 1 mm smaller restrictor.

Mirek, I think you was in hurry when you read the post.

Here’s a summary of the results.

Focus
Torque at peak power 381 Nm
Power at peak torque 290 PS
Bmep at peak torque 42,7 bar

Fiesta
Torque at peak power 371 Nm
Peak power 332 PS

There was not enough data in the article to calculate the peak torque of the Fiesta WRC. It has 6% bigger restrictor and probably a turbo more adapted to the restrictor.

If someone would like to have a different results concerning the torque for the Focus, you could try these equations.

http://www.turbobygarrett.com/turbobygarrett/sites/default/files/PDF/Turbo%20Tech%20103.pdf

If using bar, Celsius, cubic centimetre:

Wa kg/min= MAPreq(bar) * VE * N * Vd cm3 / 2 * R * (273 + Tm Co)

PS = 60 * Wa kg/min / BSFC kg/hr*PS * A/F

MAP = 4,3 bar
Vd = 1998
VE = volumetric efficiency
N = rpm
R = 2871
Tm = manifold air temperature

I can ensure you that you will have a better result.

[br21]

Unfortunately Anthony looks to be busy and in thread about his blog somebody asked about geometry settings in WRC cars. It might be still interesting for some, so for example MSport recommends toe: 0 in front and in 1mm (total) in rear both on tarmac and gravel. Camber -0,75deg front, -1,0deg rear on gravel and -1,5deg front, -2,0deg rear on tarmac, but that really depends on tires you're using. Caster around 12/13.

Also in free time this might be interesting to watch:
https://www.youtube.com/watch?v=FYbMk50awO0
nothing extra special there, but always worth watching I think.

[N.O.T]

You have a nice face Jan, a rally face... for your age i expected you to be a lot whiter and uglier... you gained a point in my book... still below threshold but a point is a point...

[OldF]

I found a page with a formula for calculation of the choked flow true a restrictor. There’s also a Java Applet calculator lower on the page by which the mass flow can be calculated.
http://www.grc.nasa.gov/WWW/k-12/airplane/mflchk.html (http://www.grc.nasa.gov/WWW/k-12/airplane/mflchk.html)This is rocket science.:D

A wikipedia formula looks different but gives the same result with Cd = 1. http://en.wikipedia.org/wiki/Choked_flow

Calculating with 1 bar and +25 oC the choked flow for a 33 mm restrictor is 0,200 kg/s. The volume is 0,200 / 1,168 (density) = 0,171 m3 or 171 litre. In the video (In br21’s post) the guy said the airflow is 70 litres per second. Dividing 171 / 70 = 2,44. Close to the 2,5 bar boost limit.

In this article (page 31) http://content.yudu.com/Library/A1wvd5/RaceEngineTechnology/resources/19.htm
is said that airflow for the Focus is/was 748 kg/h and for the Fiesta 720 kg/h. Calculated value for a 34 mm restrictor is 765 kg/h, 765 / 748 = 1,0227. In the case of the Fiesta the result is 720,7 / 720 = 1,001. I don’t know how correct the values are in the article but quite close to theoretical.