Aluminum versus Cast Iron

Getting ready for my next project, exhaust manifolds and risers. Time to get rid of the log style manifolds. These Aluminum manifolds may offer some benefits such as a weight reduction, but can they handle the heat?

What is the general opinion of these:

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the heat won't be a problem as long as they stay "wet".

I'd be more worried about what the salt will do to them and what they have been made from (grade) and what they are coated with.

If your engines are F W Cooled (closed system with antifreese) they sould last. Dont think of using them without FWC, even in fesh water!

Jeff

I do have FW Cooled. It is interesting, but a expensive test.

You bring up a good point about the salt effect on the metal. I did think about this, and I was thinking of painting them with several coats of good engine paint should I go this route. The engine room is very dry, so there is not a water accumulation problem causing moisture.

I do not have to rush into this, so I will continue reading and searching for reasons not to try this.

Thanks for the input.

I would be more concerned about the dissimilar metals corrosion issue. Aluminum bolted up to cast iron is never good. If your looking to save weight clean out some of the lockers.

I've had aluminum mans and risers on my boat for the last 9 years. I run my boat in salt water with Fresh Water Cooling. The mans and risers are cooled with Raw Water. Mine were manufactured by "Redline Marine"

Every other year I remove and inspect them. The last time I pulled them I had the mating surfaces machined on the manifolds due to some minor leaking at the joint.

I typically rinse the cooling system about 85-90% of the time I use the boat. Occasionally I am unable to rinse due to the well/pump out of service at my marina.

They still look great and have minimal corrosion when peering down into the water sleeves and exhaust port. The width of the passages is uniform and free from scale.

Everyone tells me that they are no good. My experience is quite the opposite.

Oldmako:

Where is Redline Marine? I searched but there are a lot of companies with that name. 9 years with yours are great, I am not sure if I could maintain them as well as you. I think about flushing more often.

old mako; what engine doyou have?

Ford 351. Holley 4 bbl 600cfm. Reman. Edelbrock Alum intake. All else stock as far as I know.

Redline WAS in the Pacific NW. They then went out of business. It is my understanding that someone is back in business in that area using that name. I can't offer any additional info.

Their stuff isn't cheap. BUT.....I have 9 years on aluminum used in salt water. 1000 hours of operation as of today. I can't find fault with that as most in my hood change risers every 2-3 and mans every 3-4.

Pic enclosed. This was taken two years ago. They were on the boat when I bought it and I have no idea how long they were there prior to my purchase.

Your results may vary. Professional driver on a closed track and all that.

PSSSSSS.... I change my Heat Exchanger zinc at LEAST every 50 hours. That works out to every oil change, or more often if the boat sits a while. It lives on the trailer 80 percent of the time, in salt the rest. Galvanic action will consume them in no time if the zinc is toast. I learned this the first few months I owned the boat. I had to have them repaired at a local welding shop. BOTH were developing corrosion on their port sides in the exact same place. The zinc was gone.

Since then, no problems but those zincs are important. And, cheap and EASY to replace.