Rear diffuser or rear spoiler?

[wedge]

Or would you want both?

I find it greedy and OTT having both especially if it was a small hot hatch - Corsa VXR being a prime example. I think hot hatches look better with diffuser.

[rah]

Or would you want both?

I find it greedy and OTT having both especially if it was a small hot hatch - Corsa VXR being a prime example. I think hot hatches look better with diffuser.
Diffuser every day.

[Storm]

spoiler!

of course I won't care what it had, if I had a hot hatch..

[Sonic]

None. Gimmee a Caterham 7 anyday.

[Daniel]

This is a diffuser....
http://www.mulsannescorner.com/Peugeot908Sebring2008-MF33.jpg

Not the stupid little mock plastic diffuser on the Corsa. Also can someone show me where the spoiler is on the Corsa? All I can see is a mock spoiler on that too :p

[wedge]

Daniel, that's a venturi-type diffuser. Different to rear diffusers as venturis are tunnels shaped underneath the car.

Cars tend to have F1-style though the Jag XJ220 runs grounds effect venturi.

http://www.formula1.com/photos/ta_article/full/ta_article_621.jpg

http://www.nextcar.com.au/i.renault.clio.III.2006.renaultsport.2.0.16v.diffu ser.06mar.jpg

Underneath XJ220

http://image.europeancarweb.com/f/features/8589845+pinline_medium/0505_08z+Jaguar_XJ_220S+Close_Up_Rear_Diffuser.jpg

[MrJan]

Well as I've got a spoiler I spose I better side with that, plus I can use it to lift the boot up :D

[Daniel]

Daniel, that's a venturi-type diffuser. Different to rear diffusers as venturis are tunnels shaped underneath the car.

Cars tend to have F1-style though the Jag XJ220 runs grounds effect venturi.

http://www.formula1.com/photos/ta_article/full/ta_article_621.jpg

http://www.nextcar.com.au/i.renault.clio.III.2006.renaultsport.2.0.16v.diffu ser.06mar.jpg

Underneath XJ220

http://image.europeancarweb.com/f/features/8589845+pinline_medium/0505_08z+Jaguar_XJ_220S+Close_Up_Rear_Diffuser.jpg
You're not getting what I mean though :)

The diffuser on the back of the Corsa is purely for decoration purposes and serves little or no function. The one on the Clio is actually of some use.

[AndyRAC]

You're not getting what I mean though :)

The diffuser on the back of the Corsa is purely for decoration purposes and serves little or no function. The one on the Clio is actually of some use.

What do you expect from Vauxhall??

[Daniel]

What do you expect from Vauxhall??
True!

[gloomyDAY]

Downforce is for wimps!

http://www.stangbangers.com/RiceRiceBaby.jpg

Give me some cardboard.

[AndyRAC]

Downforce is for wimps!

http://www.stangbangers.com/RiceRiceBaby.jpg

Give me some cardboard.

That's simply Awesome!!!! :eek:

[Rollo]

The diffuser on the back of the Corsa is purely for decoration purposes and serves little or no function. The one on the Clio is actually of some use.

Spoilers and diffusers on most road cars are little to no use. The reason being is that in order to achieve downforce, you need air flowing over the surfaces.
The truth is that for a great deal of time, most cars are doing less than 30mph, so the actual amount of downforce created is bugger all. Cars doing 70mph down the motorway are also not generating enough downforce to produce any meaningful effects if any. I doubt whether the one on the Clio is of any use either.

I will say this though. The rear spoiler on the rear bootlid of a lot of cars is damn useful on the basis that with a trend to rounder cars, you can actually use the damn things as a parking aid.

[Jag_Warrior]

I'd go with whichever one I thought looked the best. As for being functional, Rollo is correct: most serve little to no purpose on street cars.

Most of the gadgets that I've seen were designed outside of the wind tunnel and were more about making a car look like a "boy racer" than making it corner better or be more stable at high speed.

For handling and control the primary things to buy are the best tires you can afford. From there, move to shocks, springs, bars and brakes. Once your car is fast, only then would I worry about making it look fast. :D

[wedge]

Spoilers and diffusers on most road cars are little to no use. The reason being is that in order to achieve downforce, you need air flowing over the surfaces.
The truth is that for a great deal of time, most cars are doing less than 30mph, so the actual amount of downforce created is bugger all. Cars doing 70mph down the motorway are also not generating enough downforce to produce any meaningful effects if any. I doubt whether the one on the Clio is of any use either.

I will say this though. The rear spoiler on the rear bootlid of a lot of cars is damn useful on the basis that with a trend to rounder cars, you can actually use the damn things as a parking aid.

Would be a bit useful on trackdays

[Daniel]

Spoilers and diffusers on most road cars are little to no use. The reason being is that in order to achieve downforce, you need air flowing over the surfaces.
The truth is that for a great deal of time, most cars are doing less than 30mph, so the actual amount of downforce created is bugger all. Cars doing 70mph down the motorway are also not generating enough downforce to produce any meaningful effects if any. I doubt whether the one on the Clio is of any use either.

All true but the Rennosport Clio was built with homologation for S1600 in mind. I'll have to dig the article out but the Clio's diffuser was actually tested and does give some downforce at speed as opposed to the diffusers like those on the Corsa VXR and the Panda 100hp which are purely there to look "racey" :dozey:

[Rollo]

I'll dig out the article for you:
http://www.autoexpress.co.uk/carreviews/firstdrives/68538/renaultsport_clio_197.html
The changes aren't only for visual impact. That diffuser really works, and can add up to 70kg of downforce. The Renault engineers haven't only focused on the things you can see, either.

Again I fail to see how a rear diffuser would help on a road car.

A rear diffuser works on the basis of Bernoulli's principle to reduce the air pressure under the car and thereby increase downforce (if implemented properly).
Is there going to be any change in pressure under the car at all if said car has to be set high enough above the road to go over speed bumps, driveway entrances and provide a smooth enough ride for Joe Public? The real world maths simply doesn't add up.

[AndyRAC]

I'll dig out the article for you:
http://www.autoexpress.co.uk/carreviews/firstdrives/68538/renaultsport_clio_197.html
The changes aren't only for visual impact. That diffuser really works, and can add up to 70kg of downforce. The Renault engineers haven't only focused on the things you can see, either.

Again I fail to see how a rear diffuser would help on a road car.

A rear diffuser works on the basis of Bernoulli's principle to reduce the air pressure under the car and thereby increase downforce (if implemented properly).
Is there going to be any change in pressure under the car at all if said car has to be set high enough above the road to go over speed bumps, driveway entrances and provide a smooth enough ride for Joe Public? The real world maths simply doesn't add up.

Ah, but is it legal? ;)

[Daniel]

I'll dig out the article for you:
http://www.autoexpress.co.uk/carreviews/firstdrives/68538/renaultsport_clio_197.html
The changes aren't only for visual impact. That diffuser really works, and can add up to 70kg of downforce. The Renault engineers haven't only focused on the things you can see, either.

Again I fail to see how a rear diffuser would help on a road car.

A rear diffuser works on the basis of Bernoulli's principle to reduce the air pressure under the car and thereby increase downforce (if implemented properly).
Is there going to be any change in pressure under the car at all if said car has to be set high enough above the road to go over speed bumps, driveway entrances and provide a smooth enough ride for Joe Public? The real world maths simply doesn't add up.
Please post a link froma recognised source :)

[Rollo]

Exactly ;)

[Easy Drifter]

I thought rear spoilers were girdles on women!! :D

To be serious I know the one on my Cobalt is only good as a handle to lift the trunk open. When it snows here (often) there is absolutely no flow over it as the snow just stays or builds up. It also has no proper aerofoil shape. The same was true on a Honda Civic I had several years ago.

I have designed proper wings for race cars.

Rear spoiler or rear diffuser?

Neither, since both make you look like a knobhead.

[Hazell B]

Neither, since both make you look like a knobhead.

Tell that to Jenson Button :laugh:

But you're sooo right. In nine cases out of ten, they just look stupid. Anyone who thinks they work at all well is plain silly.

I've got mud on the back of my vehicle. It serves it's purpose.

[Malbec]

The diffuser on the back of the Corsa is purely for decoration purposes and serves little or no function. The one on the Clio is actually of some use.

The Clio one is pretty useless too, the ride height is far too high for a start.

In short, any car designed for real roads with speed bumps etc is going to be too far off the ground for a diffuser to work, and thats ignoring the lack of a smooth floor too.

For that reason I'd go for a spoiler, and even then most only reduce lift, not create downforce. Plus they only work properly once you get close to doing the ton.

[Mark in Oshawa]

Rear spoiler or rear diffuser?

Neither, since both make you look like a knobhead.

BINGO!!!

I have a little decklid lip on the back of my Chevrolet Lumina but THAT is decoration really. That said, the doofus who designed the car should have had something that shape on it anyhow because the regular stock model has a rounded rear end that looks just ...yaaawwwn.....boring.

[Jag_Warrior]

The approach taken by Porsche and Audi, respectively with the Cayman S and the TT, is pretty interesting. A wing/airfoil that extends at a certain speed, but retracts below that speed. So stability at high speed, but no added drag when you're below that speed. I believe Chrylser did the same thing with Crossfire. I haven't seen many Caymans on the road, but with a lot of TT's and Crossfires I've seen, people elect to leave the airfoils up. Hey, I guess they like the way they look. :p

That's why I say beauty is in the eye of the beholder. I went to a WRX meet a couple of years ago. I was amazed at how many guys who had STI's were even swapping their "park bench" trunks (huge STI rear spoilers) to guys who had WRX's with lip spoilers or no spoilers on their trunks - and the guys with plain trunks wanted the "park benches" on their cars. To each his own...

IMO, the truly ridiculous ones are the little wannabe gangsta kids with Honda Civics and Accords that are fitted with those idiotic coffee can mufflers and the rice boy wing setups. Turn that baseball cap sideways and do the gangsta slouch... cause you know, that's how we be rollin'.

What up, yo?! :rolleyes:
http://www.rowtow.com/wp-content/uploads/2007/12/honda-ricer.jpg

They should listen to this girl:
http://www.mopo.ca/uploaded_images/penguins-771023.jpg

[Mark in Oshawa]

The approach taken by Porsche and Audi, respectively with the Cayman S and the TT, is pretty interesting. A wing/airfoil that extends at a certain speed, but retracts below that speed. So stability at high speed, but no added drag when you're below that speed. I believe Chrylser did the same thing with Crossfire. I haven't seen many Caymans on the road, but with a lot of TT's and Crossfires I've seen, people elect to leave the airfoils up. Hey, I guess they like the way they look. :p

That's why I say beauty is in the eye of the beholder. I went to a WRX meet a couple of years ago. I was amazed at how many guys who had STI's were even swapping their "park bench" trunks (huge STI rear spoilers) to guys who had WRX's with lip spoilers or no spoilers on their trunks - and the guys with plain trunks wanted the "park benches" on their cars. To each his own...

IMO, the truly ridiculous ones are the little wannabe gangsta kids with Honda Civics and Accords that are fitted with those idiotic coffee can mufflers and the rice boy wing setups. Turn that baseball cap sideways and do the gangsta slouch... cause you know, that's how we be rollin'.

What up, yo?! :rolleyes:
http://www.rowtow.com/wp-content/uploads/2007/12/honda-ricer.jpg

They should listen to this girl:
http://www.mopo.ca/uploaded_images/penguins-771023.jpg

The girl is DEAD on the money...I think. I was sorta distracted