What's the downside?

[capz]

Saw these on Ship Shape TV. This company makes aluminum manifolds and stainless steel risers. Biggest benefit is shedding 80-100lbs at the stern. I wonder if these could cause a corrosion nightmare (aluminum manifold on cast iron block?). The site describes them as aluminum "hybrids", so maybe they have that covered. And price is comparable to oem. I've got some years left on mine but I'd consider the switch.

http://www.stainlessmarine.com/

 

[Dave M.]

I have no idea how well these work or don't work. I would worry about the aluminum. I think for your boat, getting rid of 80 lb at the stern would be imperceptible. A nice 2000 270 DA is worth some money. Putting on non-standard parts of non-standard construction seems to me like a way to guarantee it is worth less money to a potential buyer. I would not do it for that reason alone.

 

[capz]

I looked around some more. Mercruiser makes oem aluminum manifolds and risers for high performance. Also found them on Fountain, Donzi etc. There must be reason why it's not standard on all boats. I'm sure it's a longevity issue.

 

[PlayDate]

I looked around some more. Mercruiser makes oem aluminum manifolds and risers for high performance. Also found them on Fountain, Donzi etc. There must be reason why it's not standard on all boats. I'm sure it's a longevity issue.

Almost all go-fast boats have aluminum manifolds and cylinder heads to keep the weight down. Respectively they are hard anodized against the elements and rarely sit in salt water with out being flushed after each use.

Certainly, fresh water cooling would go a long way toward keeping corrosion down to a minimum on the manifold. For the elbow, most use stainless steel because of the expansion of dissimiliar metals and the corrosive effects of heating saltwater.

A few years ago I replaced the manifolds and elbows on my Sea Ray as a preventiive measure. The elbows were stainless from the factory and the manifolds were cast iron. I had several friends offer me sets of aluminum components but having to deal with the rerouting/replacing hoses pushed me back to buying Mercruiser components which are all cast iron.

The next time I deal with this, I would seriously consider aluminum for the manifolds because my engines are fresh water cooled and already have marine aluminum heads on each engine.

The advantages are weight (although I agree 100 pounds won't make our boats go faster), easier installation (weight wise), and better heat distribution. The cost differential was 2-3x over cast iron a few years ago which was hard to justify.

-John