ren274u

Thats whati mean wheelspin, couldnt think of a good word

bcc333

V8 2005 Mustang GT Premium 4.6L 3V 5 speed automatic w/ OD. Pirelli (PZERO NERO) P235/55 ZR17 98 W m+s all around (W= 168 mph) 32 psi x4 per door jam ; stock throttle body: It is a twin 55/57? mm aperture; 87 BP/Amoco


what is the stock OEM rev limit

what is the stock OEM top speed

will the Predator "tell me" or will it "assume"..... all this stuff when i do the initial download?

MusiccityGT

Stock Top Speed limit - 145
Stock Rev - 6200 ( as I recall, maybe wrong)

Predator assume? Assume what? When you download a tune it will have altered limit setting already programmed or you can reset them even in the factory tune to your desired limit.

chevykiller

The facts on rev limiter settings....

Musiccity brought up a very good point about his peak HP curve. RPM is what blows engines 99% of the time so you don't want to get crazy with your rev limiter. For most of you guys, your peak HP range is going to be between 5800 rpm - 6200 rpm. So, you would think that you would never want to set your rev limiter above 6500 rpm but here's a little secret for your guys...

There is an embedded 'torque nanny' within your computer that senses when your car is close to the rev limiter and retards the timing a fraction of a second right before you hit the rev limiter in preperation for the rev limiter being engaged. To explain this simply, what happens is your car will seem to hesitate at WOT between shifts. This hesitation (or lag) is commonly felt by most everyone and this is the reason why. The way around this lag is to set your rev limiter higher so you are making your WOT shifts far enough below your rev limiter before that 'torque nanny' program can be engaged.

So, basically what you want to do is set your rev limiter for around 6800 - 7000 rpm, but still make your shifts around 6000 - 6300 rpm. Please try not to miss a shift and floor your car at 7K though...lol

Here's how my race tune works - rev limiter set at 7500 rpm, shift light comes on at 6400 rpm, and I make the shift at approximately 6800 rpm (MY peak HP curve) STREET TUNE - Rev Limiter set at 7000 rpm, and I make my shifts at around 6200 - 6400 rpm (MY peak HP curve on street tune)

With these cushions between shift points and my rev limiter, the 'torque nanny' never gets engaged and I elliminated the hesitation (or bog) between shifts when I'm on it. In case you're wondering, it is NOT possible to turn off this 'torque nanny' program with diablo or sct. Even if you completely shut down T/C from inside the computer permenantly, this 'torque nanny' is still in effect and is also hooked up to your clutch over ride.

Bottom Line - take a look at your dyno sheets and see where you're making your peak HP before it starts to slip off and set your rev limiter about 600 -700 rpm higher. Don't try to shift at exactly your peak HP curve cause you won't be fast enough (no one is) try to shift about 300-400 rpm before your peak rpm and you should come close to hitting it on the money. If you're not the best shifter around, then even try shifting 500 - 1000 rpm before your peak Hp curve.

EDIT - and you are correct about stock limiter settings on BOTH counts. (145/6200)

bcc333

great information ChevyKiller but i have a 5 speed AUTOMATIC (w/ OD). care to offer any parameters for an automatic?

chevykiller

The autos work somewhat the same way but a little trickier. The best bet is a good torque converter and utilize the same idea (-100 to 300 rpm)

MusiccityGT

Outstanding explanation Chevykiller. I am trying to get my shifts in at about 6300 to 6400 to stay away from Nanny and it makes a big difference, hence the reason I am set at 6800. I have been launching between 1500 and 2000, letting the tires grab traction and then WOT, in you're experience, although I am far from you're 521 or more h/p is that my best bet for a strong launch? Running the race LCA and Panhard with 4:10. You're infinite wisdom is appreciated.

chevykiller

You will be very suprised at where you can grab with good tires on your set-up. If you had some MT ET Streets (26 1/2 x11-17) at about 11.5-12.5 psi with a good burnout, you would be able to grab with a launch at about 4000 rpm with your set-up. Your 60' would be cut by 3 10's I'm guessing. On street tires, what you're doing is working but that fraction of a second waiting for grab before WOT is costing you time. You would be better off to take the car out on a deserted stretch of road when you have time and practice Immediate WOT after launch. Start off as low as 300-500 RPM and work up in a couple hundred rpm increments unitl you find the maximum before you just smoke and spin. Even though you may find yourself launching at a lower rpm, you're 60' and overall ET will be better.

ren274u

For my auto the rev limiter is set at 6800, and i have the shifts programed for 6250, i find that is the best for when at the track. When i i drive around town i set my shifts to 6000 (factory points).

MusiccityGT

I appreciate your input. I will play with a little and see how it does at lower RPM's. Going to a Street Legal shoot out on the 31st which requires street tires. I may watch for some rims so I can swap out quickly with some better tires when I need.