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time or rpm shifting #2697710
09/15/19 10:43 AM
09/15/19 10:43 AM
Joined: Jan 2006
Posts: 246
ohio
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dragon Offline OP
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dragon  Offline OP
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ohio
The car I got a while back is set up to shift on time why would you not shift on rpm I can change a setting and do either. Pro and cons

Re: time or rpm shifting [Re: dragon] #2697720
09/15/19 11:11 AM
09/15/19 11:11 AM
Joined: Jan 2012
Posts: 2,603
Stuttgart, Arkansas
rickseeman Offline
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Stuttgart, Arkansas
You would think RPM is the only way but my last 3 cars were on time. I really couldn't tell much difference. If you spin at the hit the RPM might shift and leave you in 2nd gear where as the time shift won't.


2011 Drag Pak Challenger
Re: time or rpm shifting [Re: dragon] #2697721
09/15/19 11:11 AM
09/15/19 11:11 AM
Joined: Dec 2012
Posts: 1,823
Wind Gap,Pa.
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Sammy Offline
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Sammy  Offline
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Wind Gap,Pa.
Originally Posted by dragon
The car I got a while back is set up to shift on time why would you not shift on rpm I can change a setting and do either. Pro and cons


Been down this road because every run is different and if you have to peddle the throttle it messes up if you go by rpm.
I switched to air shifting manually now with a button .

Re: time or rpm shifting [Re: Sammy] #2697722
09/15/19 11:13 AM
09/15/19 11:13 AM
Joined: Dec 2012
Posts: 1,823
Wind Gap,Pa.
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Sammy Offline
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Wind Gap,Pa.
What is time shift?

Re: time or rpm shifting [Re: Sammy] #2697744
09/15/19 12:17 PM
09/15/19 12:17 PM
Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY Offline
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Posts: 52,972
Romeo MI
I prefer to shift on rpm.. main reason is IF you spin while in low gear(time) you have a better
chance of hurting the overrunning clutch.. if I spin thats the first thing I do(shift)... I dont peddle
the car.. basically if you spin you lost the race
wave

Re: time or rpm shifting [Re: MR_P_BODY] #2697781
09/15/19 02:57 PM
09/15/19 02:57 PM
Joined: Dec 2005
Posts: 11,408
Fulton County, PA
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CMcAllister Offline
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Posts: 11,408
Fulton County, PA
Everything on the track is determined by time. Every thing that happens is supposed to happen at the exact same time every pass. So why not the shift too? I'm talking bracket/.90 racing with a 2 speed.

In .90 racing, every thing after the stop comes off should be the same every pass. So...make sure the car dead hooks every time, have a powerplant with a flat torque curve and maybe even short shift it a bit, at the exact same time every pass. The big MPH .90 cars drop it into high gear just after going on the stop so it's a simple high gear charge when the stop comes off..

When I was .90 racing with a 3 speed, I would go to second a few hun after the hit, run the stop in second, and then shift to high by RPM. Sounds screwy but it worked pretty well. Like anything, you have to test, make laps and keep track of data.

If you spin? If you spin, you're done anyway unless the other guy screws up too. Make the car not spin is my advice.

Last edited by CMcAllister; 09/15/19 02:59 PM.

If the results don't match the theory, change the theory.
Re: time or rpm shifting [Re: dragon] #2697840
09/15/19 07:15 PM
09/15/19 07:15 PM
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Posts: 43,007
Bend,OR USA
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Cab_Burge Online work
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Joined: Aug 2003
Posts: 43,007
Bend,OR USA
NHRA use to have a rule that if your S/P, S/G or S/C car had a tach in it you couldn't have the box shift it off RPM confused
Hence the use of time instead to shift it shruggy
As already pointed out, both work well up
I would try both to see which one YOU like the best scope up

Last edited by Cab_Burge; 09/15/19 07:16 PM.

Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)






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