[Gary H]

I want to try a few things before next year with the race car. I'm looking into changing my staging RPM to see if it helps my car in the 60' or ET. I currently stage on the transbrake with a 4500 chip and the data logger shows the convertor flashes to 6200. I shift at 7800 rpm and it goes through the traps around 7700. 60 ft times are usually around 1.23 -1.24. The car has run a best of 8.76 at 153 mph. Any thoughts on raising or lowering the staging RPM? I've also thought about going from a 4.30 gear to a 4.11 and see if it picks up anywhere. The tires are 10.5W X 33" bias slicks

[slowbird]

I would try a converter that's about 500rpm looser

[John Langer]

What does the converter fall back to on the gear change? Where did the motor make power on the dyno? Does the tire spin at all leaving at 4500 or is it consistent? If consistent lowering the staging rpm will slow down your reaction time and 60’. Raising it will allow the car to leave harder if the tire and track conditions will hold it.

[Gary H]

Originally Posted by John Langer

What does the converter fall back to on the gear change? Where did the motor make power on the dyno? Does the tire spin at all leaving at 4500 or is it consistent? If consistent lowering the staging rpm will slow down your reaction time and 60’. Raising it will allow the car to leave harder if the tire and track conditions will hold it.

Good question on the RPM fall back number. I'll have to pull some runs and check. The engine made 1038 HP at 7200 rpm on the 4th pull but the dyno water pump had a problem after that run, and I wasn't able to get another pull at a higher rpm. The HP numbers were still climbing on the 7200 rpm pull. We called it a day and I've never dyno'd it again. No on the tire spin. I hooks well with very little to no wheel spin. I'll get the RPM fall back number and repost

[aaronman]

Converter is key. You may want to switch to radials after you optimize everything else. You will pick up .05-.10 in the quarter with radials.

[Gary H]

Originally Posted by John Langer

What does the converter fall back to on the gear change? Where did the motor make power on the dyno? Does the tire spin at all leaving at 4500 or is it consistent? If consistent lowering the staging rpm will slow down your reaction time and 60’. Raising it will allow the car to leave harder if the tire and track conditions will hold it.

I checked my data logger records and the RPM fallback after shifting is around 6800 RPM's

[aaronman]

My experience in bracket combos where repeatability is key.... you want no more than 600rpm fallback on gear change. If you are shifting at 7800 rpm you have 1000rpm fallback which seems excessive. Best for John to chime in here given his experience.

[John Langer]

I like to see a 900rpm fall back. Nothing over 1100rpm in the heat of the summer. Anything less and the converter is too loose. Anything more and it is too tight. Converter seems a few hundred rpm tight on the flash but that is always trial and error depending on where your peak torque and what hp you are making at peak tq. I would gladly give up 10-15 ft/lbs for 50hp. That could be a converter that flashes a few hundred higher. It really depends on what the dyno sheet says.