http://www.cpperformance.com/t-marin...g-systems.aspx

You can do either full or half with stainless marine. It is a dry joint exhaust so its easier than with the typical cast iron wet joint mercruiser exhaust.

In a half system, the raw water goes through the heat exchanger and out to the bottom of the manifolds, up through the risers and out the exhaust. Antifreeze circulates from the heat exchanger to block and back.

In a full system, the raw water goes through the heat exchanger and out to the risers and out the exhaust. Antifreeze circulates from the heat exhchanger to block, then to manifolds and then back.

Ok I think I've got this now...I hope...hahaha
Give me opinions
[ATTACH=CONFIG]555051[/ATTACH]

All depends on the heat exchanger size. Cooling the manifolds adds a lot of heat and you need more heat exchanger. It's why you need to know which one you have.

Mercruiser #44446
Also why is it that FWC systems require a different thermostat housing?
Is it that it diverts some water all of the time and then when it reaches temp volume just increases?

Because there is no raw water in thermo housing on closed cooling. You can -sort of-get away with an automotive gooseneck going to a T fitting that reduces to two heater hose size outputs.

Great idea didn't even think of that...the "appropriate" housing is a little expensive.