Smitty made like 100hp more by removing his Merlin heads and going to the AFR 315's. And then made way more going with more cam and etc.

Bob Loyd (FTMBob) got stuck at a certain hp level with a 540 and stock BB1 heads. More pulley led to more boost but no sway in HP. Had them ported and then boom...way more hp with same setup.

Just 2 of many examples.

Edit in: I believe both where in the 700hp level before making the head changes.

Years ago (2004/5) my engines made 720hp with a small cam and Merlin heads.

I put a decent solid roller in and power went from 838hp on the dyno. Boat went from 81mph to 87mph.

Few years later (2012) I scrapped the Merlin heads and put ARF 357's on and the boat went from 87mph to 92.3 mph GPS (no dyno).

Few years later I completely rebuilt the engines, with slightly less cubic inches (8 c.i. less), scrapped the solid roller, went with a spec'd hydraulic camshaft (Isky 9925 springs) and the engines dyno'd at 965hp and the boat went from 92.3 mph to 94.5 mph.

In summary, I'm a big fan of the AFR heads and I'm happy with my camshaft setups over the past decade I've run these engines in the Apache.

now i am confused,what is it you disagree with?

That a boosted application is similar to NA? Unless I read wrong

bob was saying that supercharged or n/a you would use the same size head on a given cubic inch engine.that edelbrock oval is a pretty good flowing head,way better than a gm rectangle port head.

Not counting for heat and extra fuel, compressing air means just that. Compressing it. Therefore the air molecules are smaller. You are putting more oxygen into the same s-ace. So. in that regard, volume runner size can stay the same.

on the other side of that coin,more air&fuel in makes more power.

^^^different topic than what I was saying^^^^ I'll see if I can reword what I said...kinda hard to type it.

I think when using a roots, or a screw, you can trade off port volume for flow. My heads are close to 330cc on my 468s. Im sure without the roots blower, theyd be lacking a bit of low end. With the roots , theres plenty of response and torque . Im sure even better with a screw .

I am going to compare my apples to your oranges. On my 575SCI, I had a set of 325 Brodix heads with 114cc chambers. I toasted the exhaust valves due to a tank of 87 that I got at a marina in TN. To get back on the water, I bolted on a pair of BB2's that I had on the shelf. They were the 365cc runner with 119cc chambers. Boat picked up 3 mph with no other changes. I didn't even change the tune.

I am not exactly sure what this means, But it would appear that MY boosted engine likes a bigger head. It made 705hp with the 325's, so I assume it is making around 750-760 now?