hi, an 091 with 4.57diff ratio and 3.1 first.... 2.1 second.... 1.5 third...... .97 fourth. with about 200hp motor, to work best in 1/4 mile would need 23 inch diameter tyres. what are your thoughts have i worked this out correctly. thanks for your help. grogy

Will have to guess some information.

Is that wheel power or FW?
Weight of car?
RPM you would like to use?

Assuming about 800kgs, and 110 to 115mph on the 1/4,
23" tyre would be 7123 to 7447 rpm

100mph would be 6476 rpm

With more accurate numbers for weight, wheel power, and engine rpm,
I could get a better answer for you.

hi, im not really sure but this is pretty close, standard weight of 57 bug on 68 pan, irs 091, motor supposedly has 235 at flywheel, rpm ....... i dont really know as yet, but i imagine it should rev to 8000 in 4th, so hopefully cross 1/4 at that rpm?????? appreciate u thoughts.