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#15075

Greg Wright
Participant

Rob, Man oh Man do the 4 cycle dirt guys get their undies in a bunch over that. What bothers me is that they insist that (example here) a 14-56 (4 to 1) ratio will out accelerate a 17-68 (4 to 1) ratio but the 17-68 will run faster on top.

  Let’s see here now, if it is a 4 to 1 ratio and the engine is turning say 6000 rpm the top speed has to be the same. I’m told I’m wrong, there could be some difference in acceleration curves due to changes in the friction developed in the drive train but 6000 rpm divided by a 4 to 1 ratio has to be going the same speed no matter how you achieve it. Again I’m told I’m wrong. Ain’t buying it.

 

I will add that with some experimentation I have found that using the bigger combination of gears will reduce some friction in the drive train due to not turning the chain around as tight a corner (drive sprocket) and there is an almost imeasurable gain that does show up on a dyno run. The gain is within the standard range of deviation but consistently showed up on the + side.

This is impossible to test with sprint type gear ratios.

Greg Wright
Rapid Racing Inc.
Vintage B-Stock Pilot
"When in doubt Gas it, It won't help but it ends the suspense."