All this is based on the assumption of using the same cam. In my situation, going to a 4.125 crank from a 4" crank will now allow me to run a bigger cam and retain the same vacuum for street driving. The bigger cam should now help the HP side of the equation. I think this is especially true with motors that are RPM limited due to a hydraulic roller set up.


10.56 at 125.6, with a 1.43 60 ft. E85, Hyd. Roller 410 magnum,full exhaust, 3500 race weight.