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Anyone ever tried to cool an outboard with a closed loop water system? Answered

I'm making a land vehicle based on a Merc 275 hp 6-cyl outboard. Any ideas on heat load, radiator size, and in general, cooling it? Anyone ever tried to cool an outboard with a closed loop water system? We can fab up anything reasonable, and would like to hold cost down. Major issues are rad size, flow rate, and electric pump choice. I already have the motor (so don't try to talk me out of that decision). It will not have the final drive on it, so no built in pump. I can choose whatever works well.

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frollard (author)2010-10-17

One thought is internal combustion engines are 25% efficient, so figure on having to dissipate 275*3 horsepower in heat (including exhaust heat)...825 horsepower = 615 202 watts *peak*

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Re-design (author)frollard2010-10-17

And add some. The internal cooling passages are not as efficient as other water cooled engines since they are using an unlimited cool water source.

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frollard (author)Re-design2010-10-17

Yeah, never thought of that -- plan on having a much bigger radiator than you'd otherwise need.

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NachoMahma (author)2010-10-17

.  This is one of those things that, if it's possible, some Redneck has already done it and posted pictures somewhere on the Intertubes. Google is your friend.

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