Is it bad for your engine to shoot flames?

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My 2004 SpecV track car backfires a LOT (runs rich), and if I give it enough fuel it shoots flames, it doesn't seem to be damaging the engine.... At 108k miles of tracking it, it doesn't even burn oil.. And has perfect compression and vacuum. It has redline 5w20 in the sump with a pureone 14610.

do any of you know if shooting flames can potentially damage anything? It's really helpful specially if some of you have experience with motorsports


***edit. To answer some questions: it backfires everytime I shift/ let go the gas. It shoots a flame if I floor it and then suddenly back off the throttle
 
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Flames out of the exhaust? Does this happen during deceleration while in gear (engine braking)?
 
How often is it doing it? Everytime you back off the throttle? Just when you snap the throttle shut really fast? I would get a wideband o2 sensor and a fuel controller and check it out. Check for leaks in the exhaust system too.
 
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I added info on my original post, yeah basically it backfires everytime I back off the throttle
 
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Hi.

Wow. 100,000+ miles of track work? Perfect compression, vacuum, no oil burning? Amazing.

In short, yes. Fuel being ignited while it is in the exhaust stream indicates a very rich burning engine. You are probably experiencing power losses as a result. They are probably not noticeable, but you can verify through a dynamometer test.

This causes heat buildup that COULD BE (not always) harmful to your engine. Your exhaust valves will be at higher temperatures, as will the components of the exhaust system. If they are not designed within a realm of error to withstand that, then you could experience lower component operational life.

Of course, excessive fuel also conflicts with the normal combustion of your engine and leads to premature spark plug fouling.

However, it varies on a case by case basis like everything else. If you are not experiencing anything detrimental, then I wouldn't worry about it.

But contrary to popular belief, flames shooting out doesn't mean more power. Rich burning does not mean more power. However, the race engines we build sometimes shoot flames out. What we do is try to minimize it from occurring because of the adverse effects it has on engine performance.
 
Originally Posted By: Rick in PA
That should kill the catalytic converter!

And then if you have emissions inspection in FL, it could get expensive.


No emission inspections here. One day, the emissions system in my Rx-7 got up and walked away. Oh darn.
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No emissions here, and the car has a straight pipe with almost no back pressure at all.

Also has AEM cold air, lightweight flywheel, crank pulley, no balance shafts, solid mounts, throttle body bypass, koyo aluminum radiator..

Nothing big, just enough to push the small engine to 200hp/205tq, but not affect reliability too much, it has stock ECU, and it runs cooler than stock.. Thts why I went ahead and ran a lighter redline oil. It's my weekend autocross/rallycross/track car
 
Originally Posted By: MrWideTires
Thts why I went ahead and ran a lighter redline oil. It's my weekend autocross/rallycross/track car


Is oil pressure ok when idling hot, or does the car rarely idle?

After the engine cools, does the oil fill hole smell like fuel?
 
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Originally Posted By: jorton
Originally Posted By: MrWideTires
Thts why I went ahead and ran a lighter redline oil. It's my weekend autocross/rallycross/track car


Is oil pressure ok when idling hot, or does the car rarely idle?

After the engine cools, does the oil fill hole smell like fuel?


yeah no issues with oil pressure, it idles rather high for some time.. and then when it comes down I usually shut it down because it gets shaky with the mounts.

Oil fill hole doesnt smell like fuel
 
No real issue. My rx8 did it aswell, however, I had a full catless race exhaust at the time.

All it is, is unburnt fuel from the engine that is igniting from the extreme heat in the exhaust pipe.

Scrap the cat and the mufflers and let the light show begin!
 
Originally Posted By: MrWideTires
No emissions here, and the car has a straight pipe with almost no back pressure at all.


Thats pretty much expected with basically a straight through exhaust. Being used for track duty I wouldnt worry.
 
sometimes it can be made worse by an exhaust leak near the engine that lets in air to let the unburned fuel burn in the pipe. Lots of times when the throttle is closed the engine is pumping fuel through, but not igniting it. This doesn't typically happen on modern fuel injected street cars that turn off the fuel at high vacuum, high rpm no load - unless it is just a pop as you crack the throttle again.
 
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