ALFAGTV6.COM

A mystery to me is why some racing cars have flames licking from the exhaust on the overrun. I don't mean turbos, but NA racing engines. And I'm not talking about the short sharp spits of flame (my 105 used to do that), but long slow big licks of flame - think V8 SuperTaxis and you'll know what I mean .

Now my questions are:

Firstly, how and why does this happen

Secondly (and I know this is childish and I SHOULD KNOW BETTER), but can I get my V6 to belch flame on the overrun?

So engine gurus - what is the go with this?

Turbo charge it..run decent boost,rich mixtures,serious ign . advance on light load and viola !!

lurid flames on over run !!!!

or activate the anti lag on the Haltech ecu...spectacular !!

or go old school with a flame thrower kit...but not sure id recomend it on our v6's..my 58 ford will get one

im with you tho on wanting to know how/why the NA cars do it...course my 69 cuda headers and glas packs NO PIPES!!! will belch some pretty nice flames

GTV27 wrote:A mystery to me is why some racing cars have flames licking from the exhaust on the overrun. I don't mean turbos, but NA racing engines. And I'm not talking about the short sharp spits of flame (my 105 used to do that), but long slow big licks of flame - think V8 SuperTaxis and you'll know what I mean .

Now my questions are:

Firstly, how and why does this happen

Secondly (and I know this is childish and I SHOULD KNOW BETTER), but can I get my V6 to belch flame on the overrun?

So engine gurus - what is the go with this?

Easy peasey.
The engine tuner sets the engine managment system to add alot of fuel on over run/trailing throttle and either cut spark or massively retard it.
The excess fuel pumping thru the combustion chambers helps to cool them. The fuel passes thru the combustion chamber unburnt or mostly unburnt and then it ignites in the hot exhaust. The flame you see out the pipe is the end result.

If you realy wanted your v6 to do something that silly, you could try some sort of dodgy fake airflow meter signal that you send to the computer when on closed throttle above a certain RPM.
Using a closed throttle switch, a variable RPM switch, they close a relay that sends a voltage that coincides with a high engine load to the ECU.
Prolly won't give you the desired results tho.

Realy stoopid and will wreck your cat. converter (which converts cats into less harmful gasses .

Not really a serious proposition for my GTV6, just suggested as a hypothetical as to how this would occur.

Thanks for the explanations - the fuel for cooling on over-run and hot exhaust hypothesis sounds plausible. Must 'waste' a lot of fuel though- which could be an issue in an endurance race (or any race with a fuel stop for that matter). Suppose it does allow extra HP, so is all in a good cause.

Yep just boost it! hehe haha har

GarthW wrote:Yep just boost it! hehe haha har

I'm quite fine with naturally aspirated

http://www.youtube.com/watch?v=gpmzGiviCJw

That pales in comparison to this mean beast

http://www.youtube.com/watch?v=_VKq8922 ... re=related



ROCK ON
R~R

I think most factory ecus shut off the injector if the throttle position goes to 0. The ecu will only supply the pulse to turn on the injectors again when it reaches some RPM value like say... 2000 rpm. I did the same for mine. On the street it pops and crackles too much if you don't turn off the injectors on overrun.

Rookie ROX wrote:That pales in comparison to this mean beast

http://www.youtube.com/watch?v=_VKq8922 ... re=related



ROCK ON
R~R

It's scarey how sad some people realy are

Some here say that you should have a big ignition advance, an another says that you would need the spark cutted or retarted big time. Which one do I want?

And what is heavy advance, ~40 degrees?
Much retard, what is that, ~0 degree, -20 degrees?

And what is very rich mixture on overrun? Is 11.0 -> 10.0 AFR enough?

This one I have to try

Tested some now. And the only setup that would pop and bang on overrun was -10deg and ~17afr.