Will a rev limiter with full throttle gearchange, such as the Armtech units from Demon Tweeks, cause the car to backfire when changing gear?

I have a difference of opinion with a mate of mine. He says yes, due to the car bouncing off the rev limiter and sending petrol into the exhaust. I can't see how the petrol explodes without a spark?

Thanks,

Adrian.

Funny, my car flames on launch control and anti-lag and I can't remember fitting a sparkplug to the exhaust... hummmm...

Unburnt fuel vapour in the exhaust gas (from, say, a spark-cut rev-limiter) can explode on contact with the air at the backbox because it receives a big dose of oxygen and the prerequisites for fuel vapour igniting are held.

Moray

As I understand it when you hit the rev limiter in an Impreza, the ecu cuts the ignition, but not the fueling...

So if you haven't got cats, you get a loud collection of pops, followed by a crackles and a bang, plus a nice flame of course coming out of your tail pipe...a feature I love, particularly useful with tailgaters http://bbs.scoobynet.co.uk/biggrin.gif

Thanks for the info guys, tailgaters - thats the general idea...

Flames would be good too. http://bbs.scoobynet.co.uk/smile.gif

Adrian.

Chucking unburnt fuel through the cat doesn't do it much good! http://bbs.scoobynet.co.uk/wink.gif I seem to remember that it bonds with the metals in the cat, rendering them inactive.

Same reason that manufacturers don't advise people to bump-start modern cars.

So there's the answer......remove the CAT!

Without an aftermarket limiter, my MY93 backfires and lobs flames out when you hit the standard rev limit, I assume for the reasons Moray gave.

PS Moray what sort of economy do you get with the ALS? and do you have any probs with washpast on the cylinders?

Cheers
Richie
http://bbs.scoobynet.co.uk/smile.gif

RichieC,

ALS is just a toy, it isn't something you could use all the time. In fact, over certain types of terrain, ALS would be more of a hinderance as it really does make throttle response razor sharp... you are either on a trailing throttle, or on boost, there is no middle ground. http://bbs.scoobynet.co.uk/eek.gif http://bbs.scoobynet.co.uk/smile.gif

Worse than that, if you ran ALS all the time, you would need to add the turbo and exhaust manifolds to the consumables list! http://bbs.scoobynet.co.uk/eek.gif

For the reasons above, I couldn't possibly give you ALS MPG figures. http://bbs.scoobynet.co.uk/smile.gif

WRT Borewash... the Motec OverRun Boost Enhancement system runs a random cut strategy that ensures that no this does not occur.

Moray

[This message has been edited by MorayMackenzie (edited 07-07-2000).]