Sheesh,
Sell a guy a blower and he buys a membership, changes names and god knows what else. :)

So right you are, the damn laundry list is starting to get long. Yanked the engine tonight and all looks great inside. Talked to Stainless Marine today and they are in the works of designing roughly the same idea I am working on. 10-psi cracking pressure check valve in the bypass and a backflow preventer on the main lines out from the thermostat housing. I think mine may make it to the water first.

figure out (with your given system) what psi it takes....anything after that is wasted....need more?????????? increase flow not pressure........that what daryel says.

we are experimenting with building a new pump here at work and took the merc pump and tested it to see what kind of output it gets.....heres what we found:

Tests done with a 2hp electric motor running at 3450rpm

-at 3450 rpm with no load restictions and pumping 10' of head the pump puts out 26gpm and 4.3 psi running through a 2 1/4" output hose and was useing just over 1.5hp to run

-at the high end of our test....still 3450rpm pumping 100' of head the pump was outputing @12GPM and generating 43.29psi!! and useing 2.4hp to do it...

I'm scanning a curve we made for it and will post it up here in a few...or if anyone wants it i can email it to you :D

There is one thing that is missing from your test Wally. The pressure and gallonage measurements would be correct with the boat not moving. However, with the boat underway, the inlet side of the pump will be pressurized, thus increasing it's flow.

yes you are correct Cord...this was stictly a bench test to see what the pump can do. :) Unfortunatly we have no way of doing that here at work! :D

What you need is a lap pool big enough to float a boat!

you mean our 5000gal test tank wont do? LOL ;) :D

Tim, so does the Stainless Marine unit have a valve assembly in it, or is it something they are working on?

An interesting topic. I would like to see someone build a better raw water pump. It is unbelievable how short a life the pump has. People change the impellers every 100 hours or so to keep from being towed in, and sometimes that is not good enough. I work in an environment where pumps (thousands where I work) are expected to run 24 hours a day, 7 days a week, for at least 5 years with no repairs and no failures. That is 43,800 hours verses 100! 100 hours of constant operation is just over 4 days. Incredible. And the service? This little pump just pumps water at ambient temperature. In the refinery it is all kinds of nasty hot stuff. Water pumps in an industrial environment can go 10-20 years with no failures, running constantly.

A better pump could certainly be designed and sold for a competitive price, I'm sure.

GO for it Wally!