Help calculating RPM

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Clone TIE Pilot

Comic Book Super Hero
Aug 14, 2011
3,827
2,565
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Galaxy far far away
RPM = (MPH × Trans gear ratio × Rear gear ratio × 336.13524) ÷ Tire diameter.
 

Ribbedroof

Comic Book Super Hero
Supporting Member
Jan 4, 2009
4,861
6,888
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Wellston, OK
You'll hate 4.10's for anything other than 0-60 full throttle runs, and 30mph cruising.
Sooooo true! Not commuter friendly, that's for sure...35 miles to work means it almost never gets driven, in my case.
 

stew86MCSS396

Greasemonkey
Aug 1, 2022
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Post #11
Sorry if I missed it but have you determined which T-10 you have? 1st gear x rearend ratio is probably equally important than final drive mph rpm.
2.54 x 3.73 = 9.47
I ran a M20 2.54 1st with 3.73s 26.6" tall tire. Take off from a dead stop wasn't objectionable and the final drive rpm was more than I was used to compared to other freeway friendly geared cars.
 

doood

Amateur Mechanic
Sep 24, 2020
549
753
93
If you have R14 or R15 tires, the OD is a bit under because of squish. Spreadsheet attached (change extension from ".txt" to ".xls").

equation is: MPH*REAR_RATIO*TRANS_RATIO*5280*12/(PI*TIRE_OD_INCH*60)


Rear Ratio 3.08 3.42 3.55 3.73 4.10 3.08 3.42 3.55 3.73 4.10 3.08 3.42 3.55 3.73 4.10
tire od 26 26 26 26 26 27 27 27 27 27 28 28 28 28 28
rpm 2787 3095 3213 3376 3710 2684 2980 3094 3251 3573 2588 2874 2983 3134 3445
3rd gear 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
mph 70 70 70 70 70 70 70 70 70 70 70 70 70 70 70

Rear Ratio 3.08 3.42 3.55 3.73 4.10 3.08 3.42 3.55 3.73 4.10 3.08 3.42 3.55 3.73 4.10
tire od 26 26 26 26 26 27 27 27 27 27 28 28 28 28 28
rpm 1868 2074 2152 2262 2486 1798 1997 2073 2178 2394 1734 1926 1999 2100 2308
overdrive 0.67 0.67 0.67 0.67 0.67 0.67 0.67 0.67 0.67 0.67 0.67 0.67 0.67 0.67 0.67
mph 70 70 70 70 70 70 70 70 70 70 70 70 70 70 70
 

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