It is roughly a 431.5 CU IN motor. I use VP MS109 which is an oxygenated fuel, however I run that fuel for primarily 2 reasons. The first is you don't have any carbon build up on your pistons and it evaporates so quickly it never washes the oil off your cylinder walls after you shut off your engine. The free bonus for me is it adds a little HP. Because my clutch has been slipping since I built the motor, I haven't had a full run yet on the motor. I have the rev limiter set at 6,400, the engine will to go 7,100. When I put the sintered iron disc in along with the new pressure plate I'll know what the car can do, assuming I don't start breaking things.