WHAT DO YOU THINK OF CLOSED COOLING ON A PERFORMANCE BOAT? I WAS READING ABOUT ALL THE METHODS FOR FLUSHING THE BLOCK AND I WONDER WHY MORE BOATS AREN'T ON A CLOSED SYSTEM. THE COST OF SALT AWAY AND ALL THE CHEMICALS PLUS THE TIME GET OUTWEIGHED EVENTUALLY BY THE FACT THAT A CLOSED SYSTEM IS A SINGLE INVESTMENT DOESN'T IT? I'M SURE RESALE HAS TO BE AFFECTED TOO. MY BOAT IS RUN IN SALT WATER AND IT DOESN'T COME OUT UNTIL FALL SO MAYBE THAT IS WHY I THINK ITS A GOOD IDEA. JUST WONDERING WHY I DON'T SEE IT MUCH.

I have been running closed cooling for years with no problems at all. While the exhaust has salt water in it and still needs to be flushed, it saves the motor.

really BIG horsepower requires really BIG heat exchangers. Heat exchanger for a 700hp motor will be around 12" diameter and 30" long.

That's the main reason.

Are you saying that if I were to raise the HP in my 496 to the 600-700HP range I would need a bigger heat exchanger?

Uhhhh.... yeah!.... the higher the compression ratio.. the more heat in the combustion chamber.... more heat in the heads... more heat in the block... more heat in the exhaust... it's got to go somewhere... The only way you get more power out of an engine is either more power pulses... (rpm)... or more air and fuel into the combustion chamber... either way.. more power... more heat...

How much HP are the heat exchangers that come with the 496 good for? I haven't look at that to include in upgrade cost.

I'd say that 500 hp will be pushing the h3ll out of your stock exchangers, although short runs at WOT or river temps under 70 degrees will probably not overtax it.

500hp WOT for ten minutes and 95 degree lake water will more likely than not have the overtemp horn going off in your ear.

Ever see the heat exchangers on a 500 hp diesel? Keep in mind that a diesel converts substantially more fuel energy into motion than a gasoline motor. What this means is that a gas motor produces less power and more heat for a given input of fuel. Also means that it is easier to cool a diesel than a gas motor.

Again, have you ever seen a heat exchanger on a 500hp diesel? Take a look and realize that you will need a larger one for a 500hp gas motor.

Then you'll know what you're up against.

Heat exchangers on the 496 are not huge but several people are running up to 700HP with whipples and not having overheating problems. As for 500 to 550 hp should not be aproblem with the factory cooling system, and a larger heat exchanger off a 502 could be installed in place of the 496 cooler if one needed to.
Raylar

Thanks for the info guys. Raylar, I am interested in your products for upgrading my engine, but I want to understand what cost I need to budget for and how far I can go.

I have been using closed cooling since 83, so far on up to 1200 HP. I hate to admit it but my heat exchanger sizing has been rather unscientific, if a little is good more is better. The smallest I used was a 6 x 30 for the 1000 HP's in BAM. If I was to do it today I would use a plate style exchanger, much smaller than a tube & shell for the same capacity.

See these links for some examples:

http://www.go-fast.com/47_apache.htm
http://www.go-fast.com/36_cigarette.htm
http://www.go-fast.com/48_express_cat.htm