i was just wondering why a lot of race cars when downshifting shoot flames out the exaust. i see it a lot in scca racing, and v8 supercars. is it cuz there running so rich? i was just curious.

 

This could be one reason. http://www.rallycars.com/Cars/bangbang.html If you have seen Initial D this is what some guy in his skyline has or someting. Talking about the misfiring system.

 

Essentially, it is due to the cars running rich with a very short and unrestrictive exhaust. This not only occurs while downshifting but also when the driver lifts off the throttle. Of course, the excess fuel is ignited when it is in the presence of oxygen, at the end of the exhaust. Race cars that have excellent fuel management systems (Audi R8), rarely shoot flames or have popping exhausts. On the other end of the spectrum, rotary engines (specifically prepared for racing) run absurdly rich and have a continuous flame coming from the exhaust. In addition, these rotary engines have been known to heat the exhaust piping itself to extremely high temperatures, damaging the welds etc.

-Jeremy


[Modified by I Drive A Saturn, 5:40 PM 1/4/2003]

 

i read stuff before about this, good article, it would help with some diagrams, does somebody has other articles?

 

My GS-R used to shoot flames out when I would shift at redline... but that's cuz I had a bent rod, apparently... found that out when it snapped. I never saw it (was driving), but I heard the flames came out a good foot... scared the hell out of me the first few times. I know it doesn't really help, but I felt like sharing.

 

The flaming exhaust is a result of engine management - doesn't necessarily have anything to do with turbos. If you have the engine run rich for a seond as you lift off the gas going into a corner, you cool down the combustion chamber, enabling you to make a leaner burn, and thus more power, coming out of the turn when you floor it. This technique is so effective that they've even learned to "program" this behavior into the carbs of Winston Cup cars. They jet the primaries on the carbs to run extremely rich, so that when the driver lifts his foot going into a turn, the engine runs rich till he floors it again. I've actually seen flames coming out of the exhaust of some of the Rousch fords during NASCAR races.

Stonebreaker

 

thanks. how hard would it be to make any car do this?

 

You'd need to change your engine management (ECU), and get a short exhaust (not very legal on the street), definatly no cat or resonator or muffler, and you'd have to drive throttle wide open all the time, so that when you'd drop the gas you'd start flaming.

 

basically its not good for ur street car. those temps will melt stuff and bust welds...but i will admit it looks cool as hell

 

Well, the domestics have been mounting a spark plug on the end of the exhaust for probably 50 years to do this. However, since the advent of catalytic converters, there's no enough unburned gas left in the exhaust to burn. So you have to put a nitrous fuel nozzle and a spark plug in the exhaust now to get flames. Added benefit of this route is you can adjust the flames.

For a detailed description, go here: http://www.nickss.cz28.com/custom.html

Stonebreaker

 

Thats just for show right? Is there any purpose in that other than show? Thats what they used in TF&TF I heard.

 

My freind had a Scirocco, and had the resonator and muffler removed and just a Monza tip installed. When down shifting to 2nd it would shoot flames 1-2 feet out the back, UNTIL he got a fix it ticket.

 

I just put my LS swap into my 88 hatch, and when we first started it with just the header it shot flames out under the car. It was kinda cool, but i didn't want to melt anything. It sounded like a rally car, it was cool.

 

If you take the header off your car and rev it all the way up to the rev limiter i bet you'll see flame.. hehe, don't know if i would try it tho... Latez