Heads stall @ .600 but cam is bigger/with boost
12-28-2009, 04:36 PM
#1
Heads stall @ .600 but cam is bigger/with boost OK if a set of LS1 heads flow 300 cfm or so at .600 lift but stall after that on a flow bench, and you have a cam thats bigger than .600 lift say .640 or so, how will that afect cylinder flow?
I know with NA stalling heads is not good , so you wouldnt need a bigger lift cam past where the head starts to stall, and i do know there is a valve train loss between the cam and valve, flex in the push rods, lifters etc.
I think the loss is about .020/.030
but not sure if a bigger lift cam with a set of heads that stall short of the cams lift with forced induction makes a difference?
meaning with FI the heads will still flow to what the valve will let through because of the forced air
I hope i explained it well enought about what i am researching
thanks for your help
I know with NA stalling heads is not good , so you wouldnt need a bigger lift cam past where the head starts to stall, and i do know there is a valve train loss between the cam and valve, flex in the push rods, lifters etc.
I think the loss is about .020/.030
but not sure if a bigger lift cam with a set of heads that stall short of the cams lift with forced induction makes a difference?
meaning with FI the heads will still flow to what the valve will let through because of the forced air
I hope i explained it well enought about what i am researching
thanks for your help
12-28-2009, 06:15 PM
#2
I have used cams that have a higher lift then the heads flow with good luck. Here is where I origionally read that it was fine to do and the reasonsing.
"The reasoning behind this is, if you lift the valve only to its peak flow point, then the valve only flows best when it's wide open. The cycle is brief and would only happen once per stroke. So to benefit from your peak flow the most, you want to lift the valve past its peak. That way the valve will pass its peak flow twice in the cycle. The result is more flow during the opening and closing event of the valve. You do not want to raise the valve much past the peak flow though, or you lose total flow by going too high."
"The reasoning behind this is, if you lift the valve only to its peak flow point, then the valve only flows best when it's wide open. The cycle is brief and would only happen once per stroke. So to benefit from your peak flow the most, you want to lift the valve past its peak. That way the valve will pass its peak flow twice in the cycle. The result is more flow during the opening and closing event of the valve. You do not want to raise the valve much past the peak flow though, or you lose total flow by going too high."