alecsammy

Are water by-pass valves needed on a 500 hp mercruiser with stock bravo pump or are they only needed for big Hp engines. I'm running dana exhaust and fresh water cooling which I still need to get. Where can I get a aftermarket if needed a by-pass valve and part numbers along with any other items needed. Thanks for any suggestions.







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Vinny P

Horse power doesnt necessarily dictate the need for water pressure by-pass valves. What does , is how much water pressure your set up generates. Of coourse, the faster you go, more pressure will be generated. Your pick up has alot to do with pressure. Stock Bravo side pick up lowers dont generally make too much prerssure at normal speeds. What is your pressure now?
I run closed cooling, CMI's, Imco lower, stock Merc pump. At 80 mph, it generates enough pressure to pin my 30 lb gauge. This winter, I replaced all my gauges. Now I have a Livorsi mechanical guage that can read 60 psi. I will try to run with the by-pass valve shut, just to see what pressure it makes. I run a by-pass that I got from Teague. Last season, kept it set to 25 psi. Still high, but OK for closed cooling.
With closed cooling, a by-pass isnt as important as a seawater cooled engine. The engine will not see the high pressures. The engine pressure is regulated by the cap, so gasket failures wont be a problem. However, you still dont want too much pressure in your exhaust and coolers. There is no need for it.

PayCheck

I"m building a couple of GenV bored and stroked to 496 w 088 heads and cometics - from what I've read 25lbs is the ideal and 50 is dangerous for blowing gaskets. Looking at the $, it makes sense to install the safety valves as they cost less than the gaskets alone!!