Not the most efficient this efficient that blah blah blah . Why buy a blower then try to sell it later to buy the larger one after you build your motor ? Buy the blower you want pulley it down (6.5 crank pulley), then pulley up after you build the motor . In the mean time drive your car and enjoy it . Use the 4.0 to influence people and make friends. p.s. my 3.4 has not broke my crank ....yet.