Exhaust Flow Numbers on Heads
 

I have a god idea about the flow intake flow rate on cylinder heads, but how does the exhaust flow rate change how the engine performs.

The reason I'm asking is that the AFR's have more exhuast flow than TFS heads and I'm trying to consider which head to go with (in the near future).

Check this link out **:)

http://albany.isoa.net/~mharrisj/fordhead.html

Steve

I think your exhaust (headers, h or x pipe) will make more of a difference in how your engine will perform than a couple more cfm's from one head over the other. Since the exhaust is sucked out of the head by the scavenging of the headers and pumped out by the pistons you obviously don't need as high of exhaust flow as intake (Wait a minute, you're an engineer so there's no need for me to state the obvious). Anyways I believe that both heads have enough exhaust flow to support the intake flow and since the TFS heads are usually a couple hundred dollars less (Actually about $400 less for those of us still stuck here in Canada ;) ) and not to mention they respond well to a basic port job whereas the AFR's are already CNC ported, I'd look that way.

I realy like my AFR heads. it is Up to you they both are very good heads the TFS TW with a little port work would be right about the same. I went with the AFR heads myself.

To my understanding, you want exhaust flow at 75% for a N/A engine, and 80% for a S/C.

thats easy, go with the AFR's. completly CNC ported, however, AFR uses cheap valve springs, so you might want to upgrade those if using a large lift cam.

Thanks guys. I wasn't sure why the AFR's had so much exhuast flow compared to the TFS heads. I was looking for that 75% rule of thumb answer I guess.