Thanks Rookie, I posted it there now.
Jeremy

If your looking for a good alum. head out of the box I Highly recommend the AFRs. If your looking to go bigger down the road & wanna do a lot of porting I suggest the Brodix. You will love having a set of alum heads, you will be able to tell a considerable difference. You mat also want to talk to an experienced BOAT motor builder, a good combo (heads, cam, rockers, intake, etc.etc.) is always better than just going BIG.

Thanks for the post
Its not me building the engines. It's an engine builder with a lot of experience. I'm not a mechanic but do want to know as much as possible. He's given me choices and want to make an educated decision. Also if someone has done this combonation before their opinion would be great. Really don't want more power just more reliability. If i could squeak more hp reliably and drop boost that would seem to make sense...

I ran AFR aluminum heads on a set of whippled 540's with 7 LBS of boost. The motors have almost 350 hrs and have been in 2 different boats. No problem. Just match the intake runner size to cam you are using. AFR has a tech line, or their are a couple of dealers on the board. Mercury Marine uses Edlebrock Aluminum heads on the 600 SCI motors. With aluminum heads you could go with more compression safely. 8.5-9.0 on pump gas. Good luck.

That sounds awesome thanks for the reply

Am i missing something here ?....Do you have something against this guy ?

In my quest and thirst for more knowledge I have asked the same question to many different engine builders and here's what I've been told:

Aluminum heads dissipate heat faster, so you can have a little more compression without the detonation.

The negative aspect, of course, is the corrosion in salt water.

These are the only two factors that nobody I asked disagreed on!

at 3500 rpm I have plenty of power, in a 1981 fully redone 39foot cigarette I run 58 mph and at 5800 run 86mph

aluminum head advantage:better port design,cnc porting available most brands,can run more compression with less chance of detonation,less weight,easier to repair, more power due to better port design.i use afr cnc ported on all my 540/565/572/598 engine combo great reliabity no problems.as far as corosion we hard coat anodize and recommend flushing with salt away i beleive they should last as long as cast iron.i am a dealer for afr have heads in stock .dave 410-956-5381. aluminum disadvantage more money

Dave,

What kind of longevity have you seen from the AFR's as far as hours run before valve job is needed? I know many people are having great success with these heads but I was curious if their exhaust seats are ground wide enough to last in a boat engine.

Thanx