Any tips for shifting by time instead of rpm?

[Chris Williams]

Don't know what class you're running, but every Super Comp (and most Super class) racers I know shift on time. But they do it for a very specific reason. With the high-hp engines these days, you need to shift early to insure that the engine will not climb RPM when on the throttle stop. If you let the engine get high into it's power band while on the stop, it will be very inconsistent.

So we, like most people in SC, shift on time. We shift at 1sec, but I know people who are shifting at 0.1sec, heck I know people who start out in 2nd... all just to stay rock solid consistent when on the throttle stop. We used to shift at 1.2sec, but looked at the RPM data and after we added HP to the engine, it was climbing at bit on the stop, so we started shifting earlier.

Again, don't know if this is relevant to you, but there it is.
Chris

[alaska racer]

Thanks for the reply Chris! Not running a stop,just bracket racing in a 7.00 to 8.50 class.Was just going to try somthing different,always looking for a edge.

[Rick Bailey]

Well in your case , if you have a playback you can do this,........lets say you really like for the motor to shift at 6800 rpm (as in my case) . Make a run shifting at 6800 rpm and then run the playback to see what 6800 rpm equated to in time. Mine is 2.25 if I remember correctly. (been a while since I've ran without the stop, w/stop it's 2.02)

Hope this helps.

Rick

[R&S Motorsports]

Having shifted on time for years I can tell you your car will most likley need to shift somewhere between 2.1-2.7 sec depending on rear end gear, trans ratio, hp etc. If you have a computer or a playback tach it would make much easier to pick your exact number, otherwise start on the low end and work your way up to your desired RPM. Good Luck

[alaska racer]

That's what I was looking for,a starting point.thanks for the help!

[Bill Baer]

Alaska Racer

We shift on time @1.0 sec. the stop comes on at .05 and off around 3.00 so we are in high gear when we come off the stop which seems to help consistency.

[Rick Bailey]

Bill but that is with how much motor.......I'd guess u'd need some motor to be shifting on the stop, or at least that what I've always been told. I'd like to try it but I'm only a 477 (bg blk chev)

Thanks

Rick

[Chris Williams]

Originally Posted by Bill Baer

Alaska Racer

We shift on time @1.0 sec. the stop comes on at .05 and off around 3.00 so we are in high gear when we come off the stop which seems to help consistency.

Almost exactly the same here. Except we go on the stop at .00, and off around 2.25 or so. We shift at 1.0 secs, and the RPM trace on the stop is like a laser line. When we shifted any later, it was much less smooth. FWIW, we have a 565BB at about 900hp.