Thank you George for this good information another good video that use put out your perspective on things is really valued around the racing world so thank you again my friend God bless
Great perspective. IV close, EV Open, IV open, EV close 👍 Are thermal barriers for the piston crown and head combustion chamber any good on an air cooled engine? I see none of your pistons have coatings.
Great info George but I would like to ask a question in cam profiles. I’ve always understood that is the lobe separation angle that makes the cam behave with a choppy idol so if lope separations the same what causes that choppy idol in cam design
The chop comes from valve overlap, intake and exhaust valve open at the same time. The longer the valves are open at the same time the more chop you have because the exhaust gas dilutes the intake charge, contaminates it and the engine actually doesn’t like it. Overlap increases as lobe separation angle decreases. Too much overlap can cause some of your fresh intake charge to escape out the exhaust and be wasted. Seems performance street engines like small LSA’s. Factory fuel injected cams typically have large LSA’s and it seems to me that would decrease intake charge going out the exhaust and increasing emissions. David Vizard swears that cams should be designed around LSA and has written a cam design software that does exactly that. I had Chris Straub spec a street hydraulic roller cam for a BBC and it falls right in line with Vizard’s math and it is an extremely awesome cam, gobs of torque! Not certain what George’s philosophy is on this and maybe he will chime in, but his ProStock stuff is max effort and may fall under different logic, but he does have some great looking street cams. I have always been curious if the Harley lope is attributed to valve overlap or the fact that the Harley fires and doesn’t fire again for 410 degrees, inconsistent power strokes.....or if both contribute to the potato potato potato.....I think it’s probably both that contribute to the sound and maybe even the exhaust valve opening point!
