We make 780 HP with 500 CI NA on the dyno at 6800 HP with 15.5" exhaust. Same geometry as the old APBA Super Cat engine spec's but with about 9 to 1 CR to run on pump gas. The heads are the Dart Iron Eagle 308 reworked by Jim Valako. The intakes are 320 cc and the exhaust ports were also improved. We ended up with intake and and the exhaust ports being equal to or very close to the AFR CNC 320. Iron heads should last forever in freshwater. "Forever" will come sooner to a few of us than than most sport boaters
Not may head porters are willing to work on cast iron....slow and dirty.

My heads were aluminum. The early race series heads. They dropped the 308cc after a while, but kept the 320 and 360cc version of the race series, even till this day.

That is some awesome power you guys make with the 308 iron eagles. Great cylinder head!

I didn't know AFR had a CNC 320.

The AFR website says 315cc, we are slightly above the AFR advertised port size. Things may have changed, but 10 yrs ago it was pretty easy to improve on the AFR exhaust port.

Would an intercooled small pulley hyd roller 525sc benefit from these heads?

FWIW, I had my Edelbrock Performer oval port heads flowed and these were the numbers;


Int#1
.400 lift 267cfm
.500 lift 295cfm
.600 lift 317cfm
.700 lift 335cfm

Ex#1
.400 lift 192cfm
.500 lift 212cfm
.600 lift 233cfm
.700 lift 244cfm

Not bad numbers on the EQ heads. The AFR's seem to have better numbers, especially when you add the CNC chamber. I guess it's gonna come down to what direction the owner wants to take this project. I finished building the short-blocks this weekend so thanks for the info.

I know the afrs he has flowed on the same bench , werent much better if any. Of course if you put a pipe on the exhaust, and a tulip style valve, the numbers go up.

Big difference is, the EQ head bare is 425 bucks. An afr as cast with cnc chamber, is around 1k each bare. Full cnc, even more.

It will be interesting to see how they flow , after some work and new valves. With a full cnc program, they are going 440cfm at 700lift . But, youre looking at 2600-2800 a pair , bare.

I paid $1350 for a bare 335 CNC AFR head. Awesome head and beautiful piece of machining but I am not going to build a max-effort engine again. Just a total PITA but was fun when it was completed. the extra few CFM just isn't worth it to me especially for the cost since my next project will be twins. Like MILD said, awesome flowing head for the $425!

Flow numbers are only a small part of the equation and not the most important. Most of these heads you guys are talking about flow a lot more air than you'll use in these combinations. Even supercharged. Port shape, cross section area, chamber design, getting the right cam and how well the head is suited for the combination will all matter way more than the flow numbers. Plus, you give me one cylinder head and five flow benches, and I'll give you five completely different flow reports. Just like dyno's. Flow numbers like .050 cam duration numbers are more relevant for advertising and spirited discussions than anything else.