I am curious to know if anyone else has ever heard of a "stutter box." I heard about them for launching and AWD Turbo at the track. Seeing how most of you have run into the problem of "bogging" while launching. I have run into this at the track myself. From what I have read and heard, this piece of equipement is used to hold the engine at a certain rpm as long as the clutch is not fully disengaged. As soon as the clutch is fully released, the engine will continue to rev up to red line. An Evo driver at the track talked to me about this after he saw my launches. I was interested in this product, and I am curious to find out if anyone else has heard of this. And/or has this product in use in their Subaru. Thanks for any help in advance, and keep on tuning everyone!

 

it's known by a few different names: two-step rev limiter, launch control, flat foot shifting.

the turboxs utec can do this, as can most any stand alone (ie hydra, motec, link, etc).

under most circumstances you need to place a load on the engine so that the throttle can be opened so that you can build boost.

i have a utec, and this feature amounts to a clutch pedal mounted switch input to the EMS. with the clutch anywhere but fully up, the secondary rev limit is engaged. this allows you to keep the throttle wide open and not be all the way up at redline. with the throttle open the engine is pumping a lot of air, which spools up the turbo and builds boost even before the car is moving.

the rev limit can be imposed by either cutting spark or cutting fuel. cutting fuel is safer since it does not dump an ultra combustible air/fuel mixture straight into the exhaust. however if one runs nitrous then you MUST cut spark if you want to keep your pistons in one piece.

the "stutter" comes from the cylinders firing unevenly as the revlimiter kicks in.

hth
ken

edit: you can also use this same feature to keep your foot on the gas during shifts. if you place your rpm limit properly the engine's rpms will be right where you need them to be during an upshift. there will be no loss of boost during a shift as would happen when you normally shift and momentarily lift off the throttle.

 

just to add my .02 but from personal experence this is a really really good way to brake stuff that is stock (ie you tranny and or engine). if you don't believe me do a search on turboxs web site or give them a call

 

Just read the TurboXS page. Now, from experience, would this be okay for a few weekend track runs? I don't plan on launching my car all the time with launch control, but I do want to do it at least once or twive at the track to see what I can run. Any further information on what you may have broken, would be greatly appreciated.