air flow ?

[Stan Weiss]

Originally Posted by rod

I have this ? if you had an intake port which flowed 200cfm at .500" lift, is there any good reason to lift the valve to.575"?
thanks
Rod

What lift do you plan to use?


What does the port flow @ .550" and .600" lift?


Stan

[Mike Taylor 3601]

with 575 lift you get to use 500 2X...basically take advantage of the peak by keeping valve open .500 a little longer

[Stan Weiss]

Ok lets map the head flow onto the cam lift curve.Flow @ .500" 200, @ .550" 200.5 @ .600 210


The cam is a Lunati that has .507" lift with 1.5:1 rocker arms (green line) and .541 lift with 1.6:1 rocker arms {blue line) and .575" lift with 1.7: rocker arms (magenta line)


Stan


PS - Let me add a little more explanation. I have the ICL set at 110. If the engine is a 350 ci sbc (4 x 3.48 x 5.7) the peak piston velocity will be @ 74.3 ATDC which is also point of peak piston flow demand. Now as RPM goes up there will be a small delay seen at the intake. But you can see how as lift has increased the flow at peak demand has also.