WILD ONE

NEW BOAT ON ORDER, ENGINE MFG SUGGESTS ALLUMINUM HEAD INSTEAD OF THE CAST UNITS. HE FIGURES 40-50 HP INCREASE PER SIDE. WE ARE MOSTLY FRESH WATER BOATER BUT WE PLAN ON SOME SALT IN THE FALL AND WINTER. HAS ANY ONE HAD ANY EXPERIENCE WITH ONE OR BOTH. I KNOW ALLUMINUM IS REPAIRABLE AND LIGHTER. I AM NOT SURE IF THERE IS A DOWN SIDE TO EITHER PIECE. COST IS NOT TO BAD.

Smitty

iTrader: (1)

Go for the aluminum heads and if you run in salt water make sure to fresh water flush when you are done.

WILD ONE

THANKS. MY BIG CONCERN WAS MELT DOWN OR VALVE SEATS COMING OUT OVER TIME. HAVE U EVER SEEN OR HEARD MUCH ABOUT THAT

Dennis Moore

There is only one advantage to aluminum heads and that is weight. The same amount of horsepower is available with cast iron but you will not have corrosion problems with cast iron. If you are making an attempt to build the lightest boat possible then you should use aluminum, otherwise why would you?
Dennis Moore

blown1500

Hello, Guys,
The cast iron heads are tough, heavy, and, WITH THE SAME FLOW NUMBERS AND COMPRESSION numbers, will make more power than aluminum. This is due mostly to heat reansfer in the combustion chamber. They don't corrode as badly as aluminum, threads don't strip as easily, and they have many other pluses.
The aluminum heads are lighter, easier to handle, easier to modify, resist detonation-the heat tranfer again-and can be repaired if you break one. Most of the newer heads are very reliable. Some do have minor problems(valve guide wear is one I have experienced), but they are not too difficult to remedy.
I especially like the AFR's. The right size on any engine is usually a significant improvement in power and reliability. There have been threads on airflow, etc. here. If you have other questions, I'll try to help or if someone has the head comparison from Chevy High Performance, they are very helpful.
Also, AFR has available an anodizing process for salt water resistance. It makes the head all black, inside and out, but is very effective and even helps power a little

WILD ONE

WNEN U SAY THERE IS KNOW GAIN OVER CAST WITH THE SAME FLOW NUMBERS? ARE U TALKING ABOUT TURNING UP THE BOOST ON THE CAST TO GET IT TO FLOW FASTER? CAUSE THE ALLUMINUM HEADS SHOULD FLOW BETTER WITH LESS BOOST DUE TO THE SMOOTH CLEAN PORTS. I THINK THATS THE ANGLE THE BUILDERS IS WORKIN ON. LEANER JETTS DUE TO THE BETTER FLOW. AM I MISSLEAD.

blown1500

Hello Wild One,
NA or forced induction, the same rules for iron and aluminum still apply. The flow numbers don't change because of the "smooth" casting of the aluminum heads. Flow numbers are whatever they are tested to be. If you smooth the average iron head ports, they will pick up some flow. Jets need to be changed for different situations, but it is not just because of the flow numbers.
You are misled, judging from your post. There are a lot of articles available on these subjects. I can give you some references and I'm sure many others on the board can help, too. pm for references.

WILD ONE

THANKS BLOWN 1500
That info helps alot. I have been looking for comparison articles on this subject. I understand what u are getting at now with the flow numbers. Thanks

Smitty

iTrader: (1)

The biggest advantage aluminum has over cast iron is the ability to transfer heat. Are you going to be supercharging these motors? If so I recommend aluminum to help keep temps down. If going N/A then stay with cast iron.

WILD ONE

HEY BIGWAVZ
THESE ARE 572 BLOCKS,1071 BLOWERS,825 HP ON CAST HEADS. BUILDER IS GUESSING 865-875 WITH THE ALLUMINUM. AFTER READING EVERONE ELSES ANSWERS ABOUT NO HP GAINS I WAS JUST TRIING TO FIGURE OUT WHERE MY HP WAS COMING FROM. WONDERING NOW IF MAYBE HE IS GOING TO CRANK UP THE BOOST FOR THE THAT RESULT. I HAD BETTER ASK.
WILD ONE