On Mon, 5 Oct 2009 11:42:52 -0700, "Capt. JG"
wrote:

I have a Westerbeke 13. It uses raw water to the heat exchanger. I don't
think the 13 is considered a big engine. I've been thinking about making
this sort of connection. I believe I first heard about it in a mag.
article... SAIL or Cruising World.. can't remember. Seems like a good idea
for a last-resort situation.

With an engine in that size range you'd probably get more pumping
capacity for your money with a large electric pump, maybe something
like this:

http://www.rule-industries.com/products/pumps/bilge_pumps/rule_3700/iid_261/index.htm

or

http://www.amazon.com/gp/product/B000O8F7RE

That would probably be 5 or 6 times the capacity of your raw water
pump.