question about the exhaust flames

[Saabaru]

I have looked at all the technical data I could find online but I can't figure out why the COT has so much blow by out the exhaust when braking. Anyone have any answers?

[call_me_andrew]

That's not a COT issue, the old car threw just as many flames out the exhaust. It's possible teams are running running their carburetors richer to compensate for the unleaded fuel, but I figured they would have dialed that back down by now.

[RaceFanStan]

As call_me_andrew stated, flames out the exhaust existed even before the COT ...
it usually occurs under deceleration & sometimes even on restarting the engine ...
it is caused by combustion of unused fuel in the exhaust due to the heat of the pipes ...
I suspect the engines are running very rich to be sure the engines don't "lean-out" & burn pistons ...
unleaded fuel could have added to the flames but most likely it is related to camshaft timing.
(I imagine the racing engines have a lot of cam overlap to make maximum horsepower.)
(Even with fuel injection I expect that the flames would still exist.)

[Saabaru]

It would take a lot of fuel to produce constant flames like that for such a long period of time (3 to 4 seconds), ther shouldn't be that much fuel passing through the engine on such a short deceleration. Cars with Anti-Lag systems that purposely inject fuel in the exhaust upon braking don't produce flames like that. I didn't know if it was something in the fuel or what, it's just something I was trying to understand.

Would they cut the spark in the engines going into the corner leaving the throttle wide open, this would generate a small jolt of energy comming out of the turn but probably wouldn't account for the extra lap (or laps) you could make by not wasting the fuel?

[call_me_andrew]

Would they cut the spark in the engines going into the corner leaving the throttle wide open

I'm pretty sure that's how the rev limiters work.

[Saabaru]

Yeah I know but there has to be a reason for that much fuel to be passing through the motor though.

[Mihai]

Yes, the CoT spits flames on short ovals and road course :
http://img209.imageshack.us/img209/1115/flame2ou5.jpg

But the old cars had the same 'fire power' :
http://img99.imageshack.us/img99/9564/flame1lo5.jpg

http://img209.imageshack.us/img209/2883/flame3fb9.jpg

The Earnhardts seem to enjoy playing with fire too : http://i57.photobucket.com/albums/g202/gr8link/orn/00.gif
http://img517.imageshack.us/img517/2690/flame4ie7.jpg

[RaceFanStan]

Yeah I know but there has to be a reason for that much fuel to be passing through the motor though.
The reason is that if a racing engine runs too lean it will "burn a piston" ...
once a "piston is burnt", engine failure occurs & a DNF results ...
the solution is to be certain abundant fuel is fed into the racing engine. http://www.motorsportforum.com/forums/images/icons/icon10.gif