Marine Application, Aluminum Heads

[Mario L.]

I'm new here to this board. A few short quick bits about me . .

I own and operate a specialty car shop in NH and as a hobby play with my Donzi power boat . . once powered by a H&M 302 Ford / Volvo outdrive. .

I found my way to the Dart site on a web search trying to solve a technical problem with my present engine configuration . . .

This Donzi is a 1969 Corsican, a limited production design, only 56 boats ever built. It now has a Mercruiser Bravo drive and a roller 302.

The present engine makes 345 HP and 333 ft lbs torque from 2500 rpm to 5800 rpm on 89 octane fuel. Note that a SBF was never used with a Bravo, and all this was built so that I could retain a left hand rotation drive, with all the original H&M parts for classic value. Lefthand drive Mercruiser Alpha's exist, but are hard to find and can't take alot of abuse caused by the boat exiting the water at speed!

My technical challenge . . . I am changing to aluminum heads . . . and presently only trailer the boat . . but will run it in salt water.

Now before I get everybody all PO'd at me my heads are AFR . . sorry . . the selection was done by my machine shop.

Right now I have fresh water cooling . .and have considered changing to closed loop cooling . . BUT this adds big weight in a small boat, and with the Bravo drive, a requirement for 2 water pumps . . . one to pump cooling water through the engine system and another to pump sea water through the heat exchangers . . which weigh a lot!! Read this as complex in a small engine compartent with small hatches . .

Ideally I'l like to avoid the closed loop cooling with antifreeze and corrosion protection, but run the engine and aluminum heads fresh water / sea water cooled.

Do the technical gurus of Dart Coatings have a solution to protect the water passages of my cylinderheads from corrosion while not effecting heat transfer ?
Right now the heads are un-used, only with the mods required by my use.

Looking forward to learning something!

Thank you,

[PRO 1]

Mario,

Something we have done at Dart for some time now is water jacket coatings. What this entails is a products developed that is actually poured into the water jacket of the head, filling it from end to end. This process will get the coating in all of the water jacket orifices. This will seal it up from the salt water and keep the aluminum away from the exposure. Dart charges $75.00 per head when we do this, and can handle doing it on your heads as well. Give our coating department a call at 248-362-1188, and ask for Omar.

Thanks
Dart

JC

[Dave F]

I asked for the marine coating in my heads. Everytime I've had my intake off and looked at the water passage it doesn't seem to have any pitting. I don't run in pure salt water though either.
The hottest my water temp gets is about 120 as well so it's hard for salt to form at that temp.

The other thing you can do is buy a product called "salt away". Flush EVERY time when you come in. Never heard anything bad about it.

Is the intake aluminum as well?

Since it sounds like you're using a T-stat, and you're carb'd, stay with a 140 degree T-stat. The coating certainly can't hurt and I'd still use the salt away.

The left handed alpha's are rare. I don't recall ever seeing one.

DAVE

[Awesome Bill]

I have to agree with Dave, there is one other thing you should think about that most never think of. As with any coatings, the ability for the aluminum to touch the water and release its heat is critical. Coatings will dampen that effect greatly. We have seen actual head tempurtures raise considerably. I do not use them with the really high powered engines. Same thing with powder coasting, kills the aluminum and won't allow heat transfer. So those pretty shinny engines run way hotter. Alky or blown engines are different. The salt away is a little messy and tiresome but works very well. JMO

[Dart Vader]

Dart uses an anodized coating that effectively "dyes" the metal rather than creating an impermeable layer on the outside of the object.
This means that heat dissipation is not altered by the process we use, which is very helpful in exactly the situations being described here.

[Mario L.]

to all that replied, Thank you!
I'll be calling DART this week and get my heads coated . . I'm pleased not to have to create a complex cooling system with 2 pumps and all the associated hardware.

Again,
Thank you,
Mario L.

[bajabob]

i have 355pro i heads on my 540 dart my motor runs 160 all day .

[Awesome Bill]

Flush the system out regularly and you won't have any problems. The Electrolites when left in is what causes the metal to be attacked. The softest metals check out first. If your a once in a while racer with salt, when your done just use fresh clean water to clean out the salt. The Dart stuff is the bomb and I was referring to the coatings other people have used, they hurt, Darts does work pretty well.