Fire breathing demons!

[neo-ninja]

Sooo... as i have said before recently i have been watching some of the "unofficial" gumball 3000 videos, and have spotted again something interesting.

 

I know heavily tuned cars have fire coming out the exausts when changing gear at high speeds (you see on some ralley cars etc..) but on the gumball there were several Ferraris, and Nissan gtrs(new GTR) that were doing the same....

 

(i seem to remember reading somewhere its to do with fuel fumes that are released as you put your foot down on the clutch that are ignited as the engine kicks in again just after you change gear)

 

My question is, is this standard when gunning it in these type of super performance cars? Or are they not standard spec cars?

[D4XNY]

I always thought the flames are just a result of a bit of over fuelling, the fuel makes it through to the exhaust tips, which if hot enough, ignites the unburnt fuel = flames.........

[Chesterfield]

The exhaust on the Fezza gets enough crap on the rear already without it spitting bloody flames out the back, same for the Zed with the speedracing rear. Im guessing non standard exhausts/CAT's on any cars doing that.

[AzzA G]

Thats what i thought. Because everything runs alot hotter when gunning it, it happens alot more.

[neo-ninja]

I always thought the flames are just a result of a bit of over fuelling, the fuel makes it through to the exhaust tips, which if hot enough, ignites the unburnt fuel = flames.........

 

 

oh lol dont quote me, thats what i read somewhere and it seemed to make sense at the time.

[D4XNY]

ha ha i wasnt quoting, its just what i thought....

 

like any forum, people will either agree, or correct you if your wrong, but thus adding to our knowledge! (i could be wrong, its just what i thought)

[neo-ninja]

soo we think that people have modded cars then? thats a shame i was quite looking forward to one day having a fire breathing GTR

 

Shattered dreams!

[Ekona]

Decatting a car + too much fuel is a very quick way to flames, very easy to do as well.

[Ian]

Decatting a car + too much fuel is a very quick way to flames, very easy to do as well.

 

I've never been able to get my z to do it though

[ARphotographs]

zmanalex's car used to spit lovely flames on track.

 

my motorbike spits flame when i'm sitting high up in the revs. Thats down to the fuelling being slightly off so it over fuels and unburnt bits get to the exhaust which is hot and pop crackle flames

 

think a few on the dukes pass run last year saw them!

[gunmetalzgt]

My ITR-DC2 used to do it all the time.

 

High revs and at night was an amazing combo

[Neilp]

my mini cooper s used to pop due to the over-run on the supercharger

[bigbramble]

The reason you get flames from the exhaust is pretty simple. Cars that run a rich air fuel ratio send a higher amount of unburned fuel down the exhaust pipe. To make a flame you need a heat source, oxygen and the fuel itself. Obviously the excess petrol is the fuel and the heat of the exhaust is the heat source. Within the exhaust itself there is very little oxygen, but as soon as the fuel gets to the tailpipe it is exposed to oxygen and providing the exhaust is hot enough it ignites. This is more common with FI cars as they generally run richer. You can get a chav special flamer kit which is basically a spark plug in your tailpipe which is a more reliable heat source and will ignite everything coming through on even a gutless 4 cylinder hatchback. A catalytic converter will greatly reduce the likelihood of getting any flames as the hydrocarbons (unburned fuel) and carbon monoxide (partially burned fuel) are transformed into water and carbon dioxide which are not nearly as flammable.

 

I remember driving along in one of my rx7's late at night through the new forest and I kept thinking I was getting flashed by a speed camera or something, until I realised it was my exhaust flames lighting up the forest around me!

[bounty78]

good explaination by bigbramble

[busa1300]

my fiat coupe used to spit flames mainly due to the unichip dumping fuel in at the limiter to stop detonation.

 

Kev

[neo-ninja]

ah so are we coming to the conclusion a standard uk car no matter what it is wont spit flames due to the cat?

 

And removing it makes it technically illegal?

[MWTech]

not neccessarily, however is very unlikely a car with a factory fitted cat will not produce.

 

especially your run of the mill 150bhp to 300bhp street cars

 

id imagine perhaps a corvette zo6 or a viper, some hefty big american power car would have more chance doing it in standard form, but it wouldnt be excessive

[kazman]

My 200sx used to pop and flame on demand. Childish but huge fun.

[Steady Zeddy]

I used to own a Ford Racing Puma which was engineered to pop and crackle on the over-run and that was with the Cat fitted.

 

I guess its just a matter of slightly overfueling onto a hot exhaust.

 

When I stuck on a CAI/popcharger/Kinetix plenum/decat/Y pipe and RSR onto my last NA Zed and didn't touch the mapping I was also getting popping from the exhaust on demand - it was just a matter of putting the foot down and suddenly backing off - the excess fuel would travel back through the non restricted exhaust and ignite along the way. Obviously not the best way for ultimate performance to ignore mapping/aftermarket ECU but it did sound cool.