Piston

SPEEDPARTS specially designed CP pistons is a direct result from several years of testing with our own project car 9-3 SSR, the final product from the testing resulted in very well made pistons. During high cylinder pressure it is common for a piston with lacking design to suffer from deflection. A piston is concav when cold so to allow it to expand at the top, but if the piston becomes deflected it can result in the piston being reshaped and almost completly straight. Then once the piston gets hot it widens too much at the top, which leads to the piston ring's placement being incorrect and causes bursts in the piston threads, as well as disrupting the rings closure to the cylinder bore. Another thing you must decide is what piston clearance you should have. SPEEDPARTS has, after a lot of testing, found that with these pistons and with an effect below 900hp 13th hundreths are what is needed, and at an effect over 1000hp up to 20th hundreth. The drawback with too great of a piston clearance is the increased risk of piston knock, espacially at cold temperatures and if the piston is too weak this can result in damaging the piston glands. The gap in the piston rings are 0.40mm on all the rings.