A friend of mine is trying to get me to port the heads on my truck and I have some data he got from a PI head he has been working with. This data was taken from the Exhaust with the stock valves.

Lift Stock scfm Ported scfm
.100 61.1 62.1
.200 100.2 103.2
.300 123.1 128.3
.400 141.8 152.1
.500 149.3 164.8

I have no Intake data. we were trying to see what was to be gained in the exhaust. He felt pretty sure, the larger Mod Max valves would pick up these numbers some more. Looks like the stock exhaust valves are 1.417" and mod max has a 1.452" valve. Not much bigger but should help. Based on these flow numbers, do you guys feel like this would be a waste of time or would there be a descent gain there???

 

No one has an opinion or info to add??

 

I think larger valves help. Makes sense, bigger valves...more flow. I have the larger valves in my heads.

Here are my exhaust numbers from my ported heads with stock valves for comparison. Unfortunately the heads were never reflowed with the larger valves.
Lift Stock scfm Ported scfm
.100 43 42
.200 92 92
.300 123 126
.400 143 165
.500 153 181
.600 160 191

 

I think the largest gains from porting and larger valves will be seen on the exhaust only. These engines have tiny valves for the amount of power and torque that they make.

If it were me' I'd install the largest exhaust valve that I could, and work on opening up the port. The intake would remain relatively stock.

 

The rule of thumb for supercharged engines is that the exhaust valve should be roughly twice the size of the intake valve correct? Gonna make the new the 3 valve heads interesting then.