i am not builder, so i can tell you eveything. If the motor is a stocker or a legend motor that needs to refreshed is the big diff in price. You send as much as you want. the main things are slotted cam gears, pinned intake cam, clutch, hd valve springs, pistons, steel sleeves, rod bolts etc. and the tricks of the builder. on a open motor if you know what you are doing you can do it. I race with a few guys that do their own motors and they are fast. The main thing with these cars is corner speed, at least at the small tracks I race at. You dont need the most HP money can buy to roll in the turn and have good corner speed. Just have a motor that will last more that 10 races. (sorry I had to say that because I am parting out a 8 race old sealed motor will all the good stuff that broke the crank@#!@#) Ihave a fresh open motor in the car now!!!