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How does antilag work?
focijohn - 8/11/08 at 05:53 PM

Hi all,
After stumbling across a 2wd saph on youtube spitting flames out 4/5 ft out of the exhaust, got me thinking.
How does this system work? Couldnt really find anything on tinternet. Not looking to do it just interested to know how it works.

Cheers

John


Howlor - 8/11/08 at 05:56 PM

Basically you advance? the timing on throttle lift off so that it fires on exhaust valve opening. This way it burns the fuel in the open exhaust valve thus pressurising the exhaust and keeping the turbo spooling to reduce lag.

Lots of turbo heat and rips through exhaust valves in no time unless you get good uns!

I think thats right!


blakep82 - 8/11/08 at 06:00 PM

anti lag? thats a turbo thing isn't it? i think anti lag is about stopping the turbo from stalling, allowing it to keep spinning, eg when changing gear, so its up to pressure when you accelerate again. but i thought thats what dump valves were for?

i thought flames were just to do with over-fuelling, or rather over fuelling on over run?

I'd quite like flames out my exhaust too but i don't have a turbo


Howlor - 8/11/08 at 06:00 PM

Retard the iginition!

Here is a link explaining it better for you.

Link

Steve


blakep82 - 8/11/08 at 06:01 PM

quote:
Originally posted by Howlor
Basically you advance? the timing on throttle lift off so that it fires on exhaust valve opening. This way it burns the fuel in the open exhaust valve thus pressurising the exhaust and keeping the turbo spooling to reduce lag.

Lots of turbo heat and rips through exhaust valves in no time unless you get good uns!

I think thats right!


i'd have thought retard the ignition?


Howlor - 8/11/08 at 06:03 PM

That reminds me of something.


This morning I was just leaving the house and a Gypsy came to the door and asked 'Do you want your shed retarred'. After explaining I didn't I carried on with my trip.

I've just returned to find that my shed has gone!


tomgregory2000 - 8/11/08 at 06:26 PM

there is an injoctor in the exhaust man that fires fuel in and burns and keeps the turbine spinning


Richard Quinn - 8/11/08 at 06:44 PM

quote:
Originally posted by tomgregory2000
there is an injoctor in the exhaust man that fires fuel in and burns and keeps the turbine spinning
Maybe on less desirable systems (not that any of them are any good if you value your engine!) Normally it's either a throttle bypass which allows air into the engine with a closed throttle or air injection into the exhaust headers. This, together with retarded ignition and fuel enrichment, causes the gases to expand within the exhaust system rather than the cylinder. It is this that keeps the turbo spinning. Needs to be noted that the higher temperature and uncontrolled running speed of the turbo leads to a pretty short life!


focijohn - 8/11/08 at 08:33 PM

quote:
eg when changing gear, so its up to pressure when you accelerate again. but i thought thats what dump valves were for?



Thats what i thought too so thought i would ask. Ill have a look at that web page a bit later.


Howlor - 8/11/08 at 08:57 PM

Dump valves just generally release the pressure in the manifold as you can end up stalling the turbo when off the gas. Therefore they do help with lag. The antilag systems however keep the turbo spooling much quicker and hence when back on the loud pedal the turbo responds much faster and boosts up again.

Steve


iscmatt - 9/11/08 at 12:09 AM

quote:
Originally posted by Howlor
That reminds me of something.


This morning I was just leaving the house and a Gypsy came to the door and asked 'Do you want your shed retarred'. After explaining I didn't I carried on with my trip.

I've just returned to find that my shed has gone!


Thats genius!! haha