Need help on Rev limitors?????
02-08-2007, 07:06 AM
#21
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Join Date: Jan 2004
Location: United States
Posts: 12,575
RE: Need help on Rev limitors?????
ORIGINAL: LetThePoniesRunFree
I respectfully disagree. With FI, the computer can shut the fuel off to the injectors much faster than the psi can dissipate in the cylinder. At high rpm levels, a complete shut off of fuel under boost would most definitely result in a extremely high a/f ratio which could potential result inhigh levels of detonation. The "leaning out" issue is definitely less problematic with non-fi engines as the cylinder pressure is not as great as a fi-engine therefore able to counteract the lean situation faster. JMO.
ORIGINAL: 2000GT4.6
The fuel cutoff will not cause a lean condition, it kills ALL the fuel, so it simply has no detonation whatsoever. If the fuel cutoff caused detonation to occur I would have a forged shortblock right now 
You will not damage the engine on your car (97targa) by reving it to the stock limiter of (I think) 6200 RPM. I have bounced mine off the limiter more times than I can count with 420+ WHP on tap and a blown setup (which makes everything worse).
All of the settings you are talking about can be changed with a handheld tuner like a SCT. There is no need to swap out ingnition parts for this setup, just buy a couple hundred dollar tuner and set the point where you want it.
ORIGINAL: droptoppony
you do understand by lowering your rev limiter you are putting your car in a higher chance of issues...when you hit the limiter the fuel cuts off...and you are then going lean and could have detonation. You should raise the limiter not lower it.
you do understand by lowering your rev limiter you are putting your car in a higher chance of issues...when you hit the limiter the fuel cuts off...and you are then going lean and could have detonation. You should raise the limiter not lower it.
You will not damage the engine on your car (97targa) by reving it to the stock limiter of (I think) 6200 RPM. I have bounced mine off the limiter more times than I can count with 420+ WHP on tap and a blown setup (which makes everything worse).
All of the settings you are talking about can be changed with a handheld tuner like a SCT. There is no need to swap out ingnition parts for this setup, just buy a couple hundred dollar tuner and set the point where you want it.
There is NO fuel in the cylinder... none. There is nothing to ignite, and there is no air/fuel ratio at all, because there is no ignition. Cylinder pressure has nothing to do with it, simply because you cannot ignite pure air.
Trust me on this, if boucing off the rev limiter created a lean condition on a FI car then I would no longer have a functioning shortblock. ANY detotnation on a FI 2v car (espcailly one making 400+ to the tire) at 6000+ RPMwill result in instant destruction. There is no second chance here (crappy pistons). I have bounced off the limiter more times than I would like to admit (tirespin in 1st and top of 2nd is a bitch) with absolutly no problems.
The fuel system completely shuts down... no more fuel is injected into the cylinders. There has to be at least some fuel in there for the spark to ignite and thus cause a lean condtion.
The fuel cutoff is there for your protection, not to cause a lean condition and destroy the engine. Its not the greatest thing in the world for your car, but bouncing the limiter isn't gonna hurt anything unless your acting retarded (like just holding it on the floor bouncing the rev limter over and over).
I think your thinking along the lines of the ECU cutting off the fuel pump, but it doesn't. The fuel pressure doesn't change, it simply shuts down the injectors until the RPM falls.
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