On motors that are producing more horsepower than they came from the factory, I'd at least run a 160deg. T-stat. I'd also raw water cool the manifolds. I feel that a good seawater pump with a thru-hull fitting is a necessity. Anyway I had experimented with a closed system on a slightly worked 454 mag motor. I ended up cooking the motor because the south bay strainer's holes were too big and the oil cooler got plugged with seaweed. I ended up building another motor without the freshwater cooling system. Also got a better strainer and even installed a Groco basket strainer in the boat. I flush every time with a Perco flushpro. No problems for 2 seasons.I also believe my Jabsco bronze seawater pump is worth the $250 it cost me. Even if you run in freshwater it's still a good idea to flush because of organisms and marine life that can plug up manifolds and wreac havoc! :eek: I would only run a 140deg. t-stat in salt water because the salt can crystalize at higher temps, and accelerate corrosion. :(
BBB:)

Audio added it to his boat. If you recall, he runs in the salt and would really benifit from it. I don't think he even got a season out of the system before he ripped it off. I can't recall the specific problem though.

I agree... your oil should be running around 200 degrees... it can go up to 250 without any problems.... 300 it starts to break down... I had an air cooled bike and the oil ran consistantly at 350... hot enough to deep fry chicken!

Just rebuilt my 500 EFI's. Ordered the system for $530 each motor. PM or e-mail me if you'd like the contact info. I don't have it on me at the moment to post.

http://i-netmarine.com/

I HAVE USED THESE SYSTEMS ON 3 OF MY BOATS AND NEVER HAD ANY TROUBLE. :D

thanks for the comments. what kind of motors did you put them on?

BOAT 1 350 ZZ4 MOTOR
BOAT 2 350 STOCK
BOAT 3 TWIN 454 BROVO MAG

ALL THREE WERE ADDED ON AFTER BEING RUN IN FRESH AND SALT WATER BUT WERE ALLI N GOOD SHAPE (SCALE RUST) THEY ALL RUN ABOUT 170 DEG.

The most reasonable price I found was from Ocean East Marine for CC. JIM
oceaneastmarine.com

Same here, that's where I bought mine.

Your engine internals will stay spotless (even aluminum heads and manifolds).Engine warms up quicker as well.If you are running aluminum manifolds I would leave the raw water to them as they will bring a lot of heat back into the motor.The only thing I don't like about closed cooling is that it clutters up the look of a nice looking engine with hoses and heat exchanger.