now this has probly been done, but me and a friend were talking lastnight and it came to me....


when you goto launch a turbo car, you dont have the pedal all the way down, so theres not that much air coming into the engine.... and so the turbo isnt spooled all the way (on a race or hot motor, a truck might, depends...)

now you cant hold WOT because it would overrev the motor... what if you dropped power to each cyl to hold the motor at a specific RPM... a rev limiter basicly.. the motor while extremely inefficent is still pushing a larger amount of air out and that spools it up more, right?

questions:

• is it more air? esp since some of the cyls arnt lighting off and therefore have less volume.....
• will the raw fuel in the exhaust hurt the turbo since its probly going to burn in the exhaust (and turbo) if the exhaust is hot?
• do people use this method to launch turbo cars already? there arnt any on the track around here...
• theres a hack for the ECM that replaces the speed sensor cutoff with the RPM cutoff... making a rev limiter.... is there a way to go one step further and make it turn on and off? then you could do it all in the ECM and not even add more parts.

 

just use a transbrake....leave w/ full boost.

 

It's the energy in the exhaust that spins the turbine, and not so much airflow. You can do as the rally racers do, and inject fuel into the exhaust manifolds to spool it up. More fuel burned = more energy into the turbo.

 

they actually inject raw fuel into the exhaust to make the turbo spool up more? cool.. never heard of that..


what effect on the life of the turbo does this have?

 

There are all sorts of launch strategies, and anti-lag stuff used.

The simpliest is:
There is a % TPS that enables Power Enrichment mode, so you work out where your at TPS-wise while you stage. Then have the none PE mode for staging, and then PE for when you hammer the throttle. So during stage mode, your running low timing and a bit rich, then intially in PE alot of timing, initially, to drive the EGT up, and coupled with the left over fuel in the pipe, kind of blowtorch the turbo with hot gases.

The GNs can typically stage at 3,800 RPM at 7 or so PSI and with the right combo, do 1.5s. The not streetable crowd with looser converters can do even better.

 

a friend of mine has a DSM, and its a manual, and of course you can't really launch a manual car on boost, but he got something he calls a "stutter box" its more or less a rev limiter, but some how allows him to build at least partial boost.. he launches at about 5 psi. i might have to go talk to him and find out exactly how it works, and what not

 

I know someone with a DSM that has something like that too. IIRC, it was built into an aftermarket chip or piggback called a "T.M.O.". I didn't get a chance to really pick his brain about it, but I do know he's able to hold it at 4k RPM on the line, and is in boost.

 

You're talking about the TMO stutterbox addon. TMO chips are insanely expensive, $300 each, for an adjustable RPM stutterbox a no-lift-to-shift adjustable rev limiter to keep boost with a manual car, a clutch operated "valet"/security feature among other things. People sell cheap copies on eBay and there is currently someone else who makes really cheap custom chips for DSMs.
MSD sells a 2 step rev limiter box, though, so you might want to check that out for your car. It really is invaluable for a drag racer.