1989 mustang drag car need 4.30 or 4.56

blueracecar · 10-07-2007

i have a 1989 gt with a 390hp crate engine and c-4 with a 4000 stall in it. i am shifting at 6500 but i cross the finish line at 6000. is there a formula i can use to figure what gear i need? 4.30 or 4.56

i forgot to mention i am running 4.10s right now

95fiveoh · 11-04-2007

http://www.allfordmustangs.com/Detailed/608.shtml

cindys_sn95 · 12-07-2007

the change from 4.10s to 4.30swill be good for about 400 rpm.the 4.56s will be more like 650-700 rpms. but in all honesty will not make much diff.in et

1fast06 · 12-15-2007

(RPMXTire diameter)divied(REAR GREAR X OVERDRIVE X 336)=mph