flow decrease vs lift
flow decrease vs lift
(OP)
I am new to this forum but have been very impressed with the information shared in the threads. I would appreciate any advice on cam lift vs flow figures. I have a set of old ford motorsport a3 heads that i have welded and reshaped the ports. They are flowing on the inlet 390 cfm @28 but they fall over at approx .740 lift and drop to about 375 and stabilize up to .850. The valve dia is 2.24 and the throat 2.010. I am running a 45 deg seat and am yet to test anything steeper, but i still would like some input on how far fast max flow lift i can go. Is it feasible to lift higher than this as i believe the gas flow dynamics may produce differing results on a running engine than they do on a steady state flow test. The flow results obtained were on a self made flow bench calibrated with a superflow calibration plate and the accuracy has been backed by flowing heads with known values. The engine is 9.5 deck windsor with 4.125 bore and 3.85 stroke and is for drag racing. Thank you for any advice.
Regards,
Ray Fuchsbichler
Windford Engineering
Regards,
Ray Fuchsbichler
Windford Engineering





RE: flow decrease vs lift
What type of cam are you running?
RE: flow decrease vs lift
RE: flow decrease vs lift
Michael
RE: flow decrease vs lift
Try flowing the heads at 36" H20 or even higher. You will here the port begin to "whistle" as the velocity at the SSR reaches the speed of sound (Mach 1).
Your throat diameter seems correct (~90% of valve dia.), but you need to pay close attention to the radius/angles above and below the valve seat.
If you have a pitot tube, perform a velocity "map" of the port. It you have any points in the port that exceed 60% of the speed of sound the port will be "choked" in that area. These are the areas that will need work.