No Subject

[dennis]

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Has anyone on this list tried to make, or used, an anti-lag system? 

For 
those not familiar with this term, some of the rally cars and other cars 
in big dollar classes that use a larger and more difficult to spool turbo 
use these systems to decrease lag. 

This system allows a car to come out 
of a corner on a track already in boost after lifting and breaking, without 
left foot breaking it and shortening pad/rotor life. Or to launch at the 
dragstrip with a manual transmission, and have boost built up already.

Some say they can get substantial amounts of boost at idle with these systems. 


Once activated, it is a system where when the throttle is closed, ignition 
timing is retarded and additional fuel is added to the engine. When the 
throttle is opened again, everything returns to normal. I think it requires 
a slighly greater amount of airflow too. This could be accomplished with 
the idle speed motor. There may be more to this than what I've gathered. 
If anyone knows more, let me know it too. 

Some systems add more fuel through 
the stock injectors, while others use a mechanical style injector in the 
exhaust manifold to inject fuel there. When the timing is retarded, combustion 
takes place later in the cycle and a large portion of the explosion that 
pushes the piston down is expelled out of the exhaust valve, increasing 
exhaust pulse pressure, and so driving the turbine wheel to a higher speed. 
The extra fuel helps this by causing backfires in the exhaust manifold that 
also hit the turbine pretty hard. This also makes pretty flames come out 
the exhaust tip. Intimidating. Cool!

Maybe not so cool for that guy tailgating you.

Some aftermarket programmable engine management systems, like Motec for 
example, offer this as part of their programming. I would imagine that you 
could build a stand-alone system that does this cheaply using an additional 
injector, some means of easily retarding timing(MSD?), a switch that comes 
on when the throttle is released, and an activation switch. You wouldn't 
want it on all of the time, just when racing(or maybe when being tailgated). 
I also think you might be able to feed the map sensor signal wire some votage(on a 2bar system), 
say just above 2.5 where it would think it's in boost, while tricking the 
02 so it doesn't freak out, to get the ECM to do this for you. That way 
the computer would think you're making boost and respond, hopefully, with 
increased injector pulsewidth and retarded timing. And since the car would 
be running rough, the idle speed would automatically increase to keep it 
running. 
 
Has anyone got a reason this MAP/O2 trick wouldn't work?

All this may come at the expense of shorter lived exhaust gaskets, manifolds, 
and turbos.
Not to mention emissions. I would also expect plug fouling issues if the 
fuel is injected through the intake. 

Stuff breaks when you try to make 
it do what it wasn't designed for. Oh well, parts are cheap-let it eat! 
;)

I'd like to hear from anyone that has any ideas or thoughts on this subject. 


TIA for your thoughts and suggestions,

dennis


 


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