[pastry_chef]

Originally Posted by Skip Fix

Harold Brookshire Ultradyne cams and did work for Lunati, Comp would change cam splits depending on E/I ratio. John Angeles on his RAIV SS car he has run for decades has a single pattern cam also.

I remember Harold's comments on splits.

I admire the method Mike Jones uses, also looking at valve size, VE and RPM (time). He does not use any relative comparison to the intake lobe as a guide. I think valve size is very key.

I recall him mentioning speed of sound in the calcs and so exhaust temp will come into play there. I have my own chained equations based from his comments and things others have shared over the years. It does give me very reasonable lobe / valve area but nailing the VE input is obviously tricky. Ever a work in progress.. maybe one day.

CamKing wrote: ↑ 04, 2016 11:50 am
First I calculate the amount of mass in the cylinder at the max RPM you want
to make power at, then I use the exhaust valve size, and exhaust port flow
to calculate the "effective" choke diameter of the exhaust port, then
calculate how much time(duration) that effective choke diameter will need
to evacuate the mass in the cylinder.

Mike Jones comment

I calculate the total time needed(duration) to evacuate the mass at peak RPM, then focus on closing the exhaust valve at the point the pressure below the exhaust valve equals the pressure above the intake valve. When I know the Exhaust closing point, and duration, I know what the exhaust opening point is.