Anti-lag devices, pros and cons?

[Richard Hoffman]

My impression of "anti-lag" is taken from the SDS tuning manual - basically
additional fuel is injected into each cylinder on the exhaust stroke and the
timing is retarded to increase exhaust temperature.  By keeping the exhaust
hot and adding extra fuel, you get combustion during the exhaust stroke - of
course since the valves are open at this point it does not affect the motion
of the rotating assembly - crank, rods, pistons.  By having an increased
volume of exhaust gas, it keeps the turbo spooled as if you simply had the
same size turbo on a larger motor.
Downsides: you compromise the durability of everything starting from the
exhaust valve and out...valves, manifold, turbo, even the downpipe is at
risk from the incredibly high EGT that results.  SDS says that is is
basically not worth doing on a street car.  A race car, it makes perfect
sense!
HTH
Richard
1990 CQ 210K
1970 100LS 2-dr 46K






>From: Mihnea Cotet <c_mihnea at yahoo.com>
>Reply-To: mik at info.fundp.ac.be
>To: quattro at audifans.com, 200q20v at audifans.com
>Subject: Anti-lag devices, pros and cons?
>Date: Tue, 22 Oct 2002 06:28:34 -0700 (PDT)
>
>Title says it all, what are the pros and cons
>(especially the cons) for anti-lag systems? Increased
>turbo wear? Worse fuel economy? I saw this in an
>article about the Peugeot 206 WRC car that puts out
>300+ HP and 650 Nm of torque at 3550 RPM and it uses
>an anti-lag system that seems to work pretty well, so
>I thought "why not?"...
>
>Any valuable BTDT or more specific info is welcome!
>
>
>Mihnea
>
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