Caught this tonight on youtube. Thought it was a cool test. They had a 410ci Ford engine. They bolted on 3 different heads. A 165cc, 195cc, and 220cc . All AFR heads, all CNC ported. I thought the dyno results were interesting. Especially that the Torque output in the lower rpm range , was nearly identical with the 165 and 220cc.

165CC = 471hp /515TQ
195CC = 484hp/520TQ
220CC= 474hp/512TQ

Talking a difference of 13hp, and 5ft lb of tq difference between all 3 heads. But on the internet, you'd hear how one head would be killer, and the other one couldnt even get out of its own way.

I dont know why it wont let me embed the video ?

next steps should be the race track.

But yes, same discussion, the LS heads huge runners on small cid engines are horribly slow and unresponsive, Sarcastic of course. LOL

Here is thelink anyway.

The forum moderators said this issue was fixed. Guess not.

Interesting joe. Dual plane smaller cam engines less sensitive to runner size is my take but... We don't know for sure but I'd imagine afr chose the runner size friendly cam to come in so close with three different heads. Would be interesting to throw more cam at it with a SV single plane intake. Then duplicate test. Regardless good info and most of all it must be nice to hang out with friends / co-workers and experiment on a dyno day in day out. Lol...

the 220 head has a bigger intake valve but because it wouldnt fit it uses a smaller exhaust valve than the 195. I wonder if the greater difference in valve size is choking down the exhaust flow and hurting it.

I would like to see that 220's potential compared to the 195's say in a moderate 625-650 build. Maybe it's for a lazy intake runner that doesn't need the exhaust or poor exhaust applications. Hah. Not sure the method behind it other than R&D.

I looked up AFR's flow chart (sbf 220's) int vs exh and the exhaust advertised is better than I woulda thought. 195's not far behind though.

Doubt any of these heads would show more speed on the GPS.

I built a 347 SBF for my Cobra replica using those AFR 195 heads. It made 516 HP at 6500 RPM and 460 ft. lbs. of torque at 5300 RPM. Running 8 stack IR EFI w/ Holley HP ecu, and a mild HR cam. I'm a believer in those heads for sure. Lots of fun in a 2300 lb. car!

Bob.

I think it could be that, or, that it simply isnt turning enough RPM to see the benefits of the larger intake valve. That 1.94 valve is probably enough valve area for that engine, until around 6000rpm or so. The big 220cc port and larger intake, smaller exhaust , would in my guess, start showing gains if the engine was revved higher , like closer to 7000rpm.

As much as we try to pick the right size head for our engine builds, which is easy to do when you are buying new, or have an unlimited budget, sometimes we must work with what we have. I dont see anything in this test, or the other magazine test that ran several bbc head sizes on a 496ci, that was dehabilitating to power production.
Big-Block Heads Shootout - The Big O Vs. The Big R - Super Chevy Magazine
355cc edelbrocks
574ft lbs at 4000 723hp at 6500

300cc afr's
587ft lbs at 4000 729hp at 6500

I doubt 6 peak HP will make a difference on the GPS, or 13ftlbs (2%) for acceleration. Prob why most big name head porters, dont get all worked up over port volumes.