tell me how you measure a dome of a hemi piston when the piston sticks out of the cylinder? I had the discusiion with Jim lerum saturday night, maybe he can explain it to you? The whole NHRA spec thing is very confusing in the way you get to the actual compression. For example, it says the cc of the ls6/l88 chamber can be 106cc, how can you do that when they start out at 118cc? You cannot deck the head that much!! If Dan and Bob approve it, it's legal. Like i always say, you cannot be a little bit pregnant!!
Mr morgan asked---tell me how you measure a dome of a hemi piston when the piston sticks out of the cylinder? Same way they did it at my certification with my domed pistons. First CC the cylinder head to get your volumn of the chamber-( you'll need it later to figure total compression. And your head gasket volumn. But first I will answer your question. Lower the piston with a dial indicator into the cylinder 1" ( or to a known distance) so that the whole piston dome is in the cylinder. Seal the cylinder with a film of grease and a plexi glass plate with a hole in it. Using a burette (a Graduated container for measuring CC volumn) and alcohol or colored fluid pour in the cylinder till full . Deduct the CC's used to get your total. Then times your cylinder bore- times Volumn used -to get your Dome volumn. NHRA street hemi Maximum dome volumn is 88.3( aka 70 cuda's and challengers ) -That according to the rules would be Anything Over .000 deck being a postive dome. And should not exceed 88.3 cc's- And that works for ANY deck height. And being the dome numbers and description comes out of the Mopar perfomance and NHRA ,I think there pretty reliable. Tim
What the basic engine math or the Mopar performance tech articles and specifications????? Which ones?ou: o No:
