Good one ray!.

If using alum heads is so much more efficient then iron heads you would think it would be a merc standard then?
It couldn't be that much more $$ ?

100 less pounds is like leaving one of your kids back at the dock

that is one thing i dont understand....with their expertise and knowledge,why didnt gm or merc build a better,more efficient head for that motor?almost seems like they build those ''chitty'' heads on purpose....whats the point?

Leaving the bitc# home. That's 100lb that really slows a boat up big time. And cheaper than a set of aluminum heads

Probably because iron heads are cheaper, hold up better in salt, and probably stand up to overheating better. Merc did use aluminum heads on the 900sc, and I think the 525efi

and thats exactly the point if most guys on here swear by alum heads and yet merc,volvo use the iron ones, theres gottta be a reason. what do the the other major engine builders use (teague,sterling ,chief etc) it really cant be the $ savings..could it be lower maintenance

You can also port heads like the Dart 308 Iron Eagles to flow as well as heads like the AFR 320 CNC. About any head can be made will work with blowers, but the trick is making power with a flat torque curve in a NA application. Who can make cast iron and aluminum heads work in marine? Jim Valako....
Save your time and $, it took me 10 years and numerous mistakes to figure out how good Jim is in making power.

I siezed an engine from a blown impeller at 3/4 throttle and had to paddle back to shore. Took about an hour to replace the impeller, check the oil, and I was back in business. Try that with aluminum heads

My comments and plug are for our aluminum cylinder heads that only used on the 496 closed cooling equipped marine and vehicle engines. Iron heads are preffered on a raw water cooled marine engine that is used in salt water, If an aluminum head is used in a raw fresh water and serviced properly it will hold up just fine. As for overheating an engine, iron heads can crack as easily as aluminum heads can warp and crack from serious overheating. As for the 100lb. weight savings , I would never tell a boater to buy aluminum heads just to save a 100lbs. I can tell you as an expierenced engine builder I can always make more power from an aluinum cylinder head than I can from an iron head, why, because I can put more compression in the cylinder without the detonation from the added cylinder temperatures seen with an iron head at the same compression ratio. Show me a 2002 or newer design engine with iron heads! Seen a few racing engines in the last 20 years and I have seen almost none using iron heads by choice!
Iron BBc heads have been in the marine engine trade for years and will be here for a few more, but not much longer than that.

Best Regards,
Ray @ Raylar

I agree with everything below..... Aluminum heads can be repaired, you can run more compression which increases cylinder pressure and makes more power, they are lighter, they don't crack as easily as iron, dissapate heat better which is even more important when running low octane fuel 9less detonation prone).