Aluminum Heads??

[Riley]

Okay guys, here's a tech question for you. Are there any reasons for not using aluminum heads on a marine engine, other than the question of corrosion?

I'm planning on re-powering this winter, and I see a lot of the crate motors available out there use aluminum heads. If the engine builder uses the proper freeze plugs and head gaskets, and the boat is only to be used in fresh water, is corrosion still an issue with aluminum heads?

If not aluminum, which iron head do you guys like? I'm reading and hearing a lot of good stuff about the GM Vortech. I realize the intake valves are a bit small, but the head seems to be really efficient, and you can't beat the price!

Look forward to your ideas. Thanks.....Chris Riley

[rayjay]

Use the Vortec even with the smaller valves. If you do a little bowl work then you can put in larger valves if you feel this is necessary. Vortec's are a good high velocity head that will flow more mixture than you think because they are efficient and maintain a very high velocity and flow a lot at low lifts. Do a little bowl work, back cut the valves, and get a good radius valve job to wake them up without doing a lot. World Products makes an FE "Torquer" head (high velocity) that works pretty good, and they are supposed to come out with an FE head that uses high velocity ports with the fast burn combustion chamber. Vortec's require using special intake manifolds. One comes which comes with the 8 or 900 dollar Vortec conversion kit from Chevy. This is not a real hi-rise manifold, but it is FE. There are aftermarket hi-rise manifolds available, but they will be made from AL.

As for using AL heads and manifolds, I am interested in getting some information on doing this by going to fresh water cooling. I am currently working on a turbocharged BBC as a personal project, and then will be looking for a boat to put it in. I always wanted to build a turbo or super charged engine, and now I am getting to do it. From an efficiency point of view, it would work much better (and weigh MUCH less) if I could use AL heads and manifold. Also, most of the Banks turbo setup I have is AL. I will have most of it coated with one of the ceramic hot coating processes for surface corrosion protection and heat retention in the exhaust manifolds, but the water passages except in the intake manifold can not be coated because of heat transfer. How well does fresh water cooling work in a closed compartment like one of the "classics" and how does one go about plumbing this to make it work correctly?

rj

[This message has been edited by rayjay (edited 08-18-2000).]

[Forrest]

Aluminum heads are great . . . with fresh water cooling that is. The simple fact is that they will corroded quickly even in so-called fresh water. Unless you run your boat in water is is sutiable to drink, the minerals combined with heat will corrode the cooling passages. I know what you are thinking. Outboard motors blocks are built of aluminum and they survive in salt water year after year. Well, the aluminum used in building an outboard motor is a different alloy than the aluminum used to build automotive aluminum cylinder heads and intake manifolds. Short of going to fresh water cooling, consider using aftermarket iron heads such as Dart Iron Eagle, World Products Sportsman or S/R Torker heads. . . and for cheap, iron vortex heads don't look to bad either.

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Forrest

[Blewbyu]

I have an X-18 that has the 5.7 Bowtie H.O.
ZZZ motor that went into the engine hole in 1991 and hasn,t been out yet for anything.Motor now has 542 hrs on it-has Glenwood log type manifolds with rear risers-also aluminum.The boat is raw water cooled-and has run the vast majority of it's life in Lake Washington (Seattle area).It has foraged twice into Puget Sound salt-having been flushed on it's return to Lk Washington.
Running the 140 degree thermostat to avoid coking up w/salt and/or acids.If you can live with an engine that only goes 10 yrs or so before you MAY have to replace heads/manifolds/etc-then it's a not bad deal.Believe you can still buy this 345hp engine for less than $3000.00-and ya really have a hard time trying to scatter it.Seems nearly bulletproof, and GM did the engineering guesswork for you (two years).
Regards-Jeff

[This message has been edited by Blewbyu (edited 08-19-2000).]

[Riley]

Thanks for the info, guys.

Rayjay, I agree with you on the Vortech heads. At this point, if I decide to go with iron heads, I'm 90% sure I'll be running the Vortech. I'd like to keep my new engine in the 5000 to 5500 rpm range, and I think these heads will be adequate at that rpm. I also like the fact that with the Vortech combustion chamber design it is possible to run a higher compression ratio without detonation.

Forrest, I don't know about drinking the water up here, but Northern Lake Huron is pretty darn clean. It's easy to see bottom in 12-14 feet of water. Although I've never run AL heads in a boat, I recently pulled an Edelbrock Torker intake manifold off of an engine my dad and I built for one of our Chris-Crafts, and the cooling passages looked like brand new. And this was with 8 years on the engine. Are automotive aluminum intake manifolds made of the same alloy as AL heads?
By the way, this boat ran an open cooling system and no thermostat.

Blewbyu, how does your boat run with the ZZ engine? Did you change the head gaskets to a marine gasket? What type of prop are you turning? Speed vs. rpm? I've often thought that engine was a great buy, but I wasn't sure how it would run in a boat.

Thanks again, guys. I love the exchange of info and ideas available here on this board....Chris Riley.