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so im in my daily driver(93 4 door teg) and i pull up to the stop lite. im one car back in the rite lane and there's a guy in the middle lane at the front in a white EVO revving his engine repeatedly. but olny one thing surprises me... one time he revs and a big shot of flame comes out the tail pipe. i was like wtf!! i thought that only happened in the movies?? how the hell does this happen? i kno it has something to do with the turbo but could someone please explain to me how this occurs.
 

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there are actualy flame thrower kits that you can get. There illegal, but i'd bet that was what it was. Pretty much, it puts a spark plug at the tail pipe and ignites gas from the tank. it dosnt just happen in movies though, just look at any pro drag racing competition. I wouldnt think that a car with that much power would be street legal or even drivable.
 

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I recall reading that if you let the blow off valve vent to the atmosphere (instead of back to the intake), that can cause the fireball effect on cars that rely on a mass airflow sensor. The air that gets released from the blow off valve has already been metered by the airflow sensor. So, if that air never makes it to the engine, too much fuel will be injected for the amount of air actually being used. That creates a rich condition - a chunk of fuel is left unburnt. The theory is that the exhaust gasses are still hot enough when they exit the tailpipe to self-ignite on contact with air (oxygen), thus the fireball. Whether or not the exhaust actually is hot enough, I don't know.
 

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you dont have to mount the plug at the tip.... . you can mount it in the pipe somehwere with something simalier to an o2 sensor bung welded into the pipe.... . . the flame will find its way out..... flames always do. .

Chris
 

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fire out the exhaust, 4 causes im aware of:

1: Big ass fireball, or constant flames = flamethrower kit. the way i do these is a i weld a bung in the exhaust and use a blaster ss coil to fire that spark plug. at the same time I run to the same momentary switch a relay that cuts ignition. fllor it, it the button, houston, we have ignition

2. lil blips, purple flames, things like that. my crx and the impreza 2.5RS do it, its caused by a big cam, mixed with some hot exhaust. unburnt gas gets pushed out the exhaust. blip blip

3. decent lil blast of fire. overly rich conditions, caused by exactly what bobski said, or by bad fuel tuning, especially on cars like WRX and EVO;s. I know for a fact this can happen, mainly on non catted cars. our WRX almost does it, when i run the BOV full atmosphere.

4. coolest flames ever, antilag system, for laucnhing and FTS. basically this is ignition cut, instead of fuel cut like what i use for launching. it keeps the turbo at full boost. also createds lots of fire dumping unbrunt fuel out the back in an extremely hot condition. this kills your tuebo extra quickly.

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Speaking of backfiring, my '91 Si does it all the time if I quickly raise off the throttle. Must have something to do with my free-flow exhaust- I'm running a OBX 4-2-1 header, stock cat, 2-3/8" OBX B-pipe, and a Ractive muffler w/ a 2-3/8" input and about 1-7/8" output pipes (3" dual-DTM).

And if it doesn't backfire, I'll at least get a burbling sound as the rpm's drop.

(see the Avatar for the exhaust)

The wife's DX (auto) with roughly the same setup (same muffler, but Megan Racing Header and DNX B-pipe) doesn't do it, I imagine because of the slushbox?
 
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