We took Kelly's car to IA Performance here in Tucson yesterday to do a couple of pulls. This is the same dyno we used last time (Dyno #1) with the log head. The drive train is exactly the same as before except for the Classic Inlines aluminum head, Oz intake and Holley 450 CFM carb. These numbers are at the rear wheel, not the flywheel.

Aluminum head with the custom Hogan intake manifold

If I compare the log and alum head torque curves at the same rpm, say 4000, then I get a much better picture. At 4k rpm the best log torque number was: 325ft/lbs. The best Alum. head torque number was: 405ft/lbs. So the torque curve is now much flatter! Much more usable area under the curve. This would explain our increase in 1/8 mile speeds.

Our Air/fuel ratio was fairly stable at 11:1 running nothing but E85. So I'm going to reduce the jets a little to lean it just a bit. This should help pick up a few more HP. All of the above pulls were made at approximate. 17lbs. of boost. We did get a boost spike of 18.8lbs at about 5k rpm on the first pull with the alum. head. But according to the numbers it didn't effect the outcome. We were probably already past the cam profile. New cam will be on order soon. I'll see if I can scan the charts in and I'll post them.

Aluminum head with Classic Inlines 4V alloy intake manifold.

I think that you N/A guys will see more percentage increase than we got with the head swap. So I take this to mean that boosting a log head really helps it's flow characteristics over boosting a "good flowing" head.

If you look at 5.0 head swaps, you'll see the same basic 40-50hp increase that we got with the Classic Inline cylinder head. Therefore, I think we're very happy with the results, and we'll keep trying!