Thread:

Water pressure BBF

i was playin with my setup this past weekend. i run in very cold water.I found that if i restict water in ,to get engine temp, i don,t have enough pressure to open the basset valve ,overheating headers. if i get enough for the headers,no engine temp. if i restrict out,pressure hits 50@ WOT with dump backed off all the way.just have to keep playin with it

Originally Posted by corbin5754

And wouldn't a regulator work the same as a gate valve.

No, a gate valve is a fixed dimension. 1 turn open is constant size regardless of the pressure. A regulator will adjust the size of the opening to regulate the line pressure. So at idle the regulator portion of the valve is closed allowing all the water to flow into the engine. When the pressure increases with higher RPM the valve will start to open to dump excessive PRESSURE. Motor should never see anything higher than what ever the pressure relief is set at unless the volume of water exceeds the size of the dump valve.

Originally Posted by rogerroost

i was playin with my setup this past weekend. i run in very cold water.I found that if i restrict water in ,to get engine temp, i don,t have enough pressure to open the basset valve ,overheating headers. if i get enough for the headers,no engine temp. if i restrict out,pressure hits 50@ WOT with dump backed off all the way.just have to keep playin with it

It's been discussed many times here about engine water temp VS engine oil temp. Most jets will never see water temps above 130*-150* at cruise. You have an open loop cooling system with a never ending supply of cold water. What you should be looking at is oil temp. I'm not near smart enough to get in to thermal dynamics of the cooling process, but if you can get your oil in the 180*-220* range that's much more important than seeing 180* on the water gauge. This is one of the reasons for clearancing a motor for marine application.

My suggestion to both of you is to feed your motor the water, don't restrict the flow to the engine. When you don't have enough water to open the Basset T how much water do you think is actually in the block? Another way to reduce pressure is to add more ways for the water to get out of the motor. Many guy's here feed their motor with a single -8 or 1/2" line off the pump and then dump it with two -10 or 5/8" lines. This over doubles the size and amount of available dump lines.

As far as the water to the headers, I would T off one of one of the dump lines to a gate valve and then to your basset T. This way you can control how much water is getting to you headers. With 2 dump lines off the motor, you may not even need to close the valve at all.

Originally Posted by Last Mohican

I have a feeling when Corbin gets the pressure gage on his motor it is going to read well within spec. His boat has center rise exhaust not headers. If it is over pressuring the block he has another issue he needs to hunt down. I strongly suggested he add a gauger because of the issue he had with water in the oil & cylinders. The only way to know for sure is to put a gauger on it and see what it reads. Anything else is just a guess. A gauger is cheap and easy to install. If he has the same issue again he will know if it is being caused by block pressure or not.

Before I spent a bunch of time re doing the plumbing I'd make sure I had a pressure issue first.

I agree that a gage is a good way to see what exactly your pressure is in the motor and then you can decide on a way to address your issues.

Originally Posted by bp298

some people will run header water from the engine outlet, some will run it off the engine supply line. when i ran water cooled bassetts, i always t'd off the engine supply line, off the pump.
the reason is, the bassett t's spring loaded ball valve is designed to open at a specific pressure. pump pressure should be directly proportional rpm at the lower rpm levels. meaning at idle (less than 1000rpm), pump bowl pressure (which is where the cooling supply comes from) is 12-15psi. it will be less at the t due to line loss. at 1500 rpm or more, bowl pressure is going to be 20-25. this will be fairly consistent.
but when opening and closing valves all the time to try and control pressure and temp through the engine, things change. you don't need in excess of 15psi through the engine to control temp, but you do need to generate more than 15 psi to open the bassett t.

what you were referencing as a regulator is a bypass. a bypass is effective in controlling downstream pressure up to a point. but when the supply pressure exceeds the capability of bypass flow, downstream pressure will be elevated beyond the desired set point. for a 500-600hp application, the bypass should be sufficient. when you start getting into 800+, it's not uncommon for that supply pressure to exceed 250psi. a pressure regulator has a diaphragm that will modulate to maintain outlet pressure at what it's set for.

what's happening here is that pressure has been controlled manually to 16 psi at wot, which will be somewhat less at less than wot. the engine outlet water has two choice of where to go - either straight to overboard (no restriction), or through a bassett t and small reducing orofices into the bassett loops (big restriction). the water will choose to go where there's less restriction. trying to do this manually, what could possibly go wrong? trying to get any kind of balance in engine water exit temp from idle to wot will be difficult. which is why i would have used the supply side for the bassetts in the first place.

See, I knew someone smarter than me would come along and correct my ramblings. More than anything I was trying to explain what the objectives where in plumbing their boats. I figured getting the terminologies right wasn't as important as the concept. I agree on your plumbing of the Basset T as being the better way. I had seen this way before and forgot about that when I was giving my advice.

Disclaimer to anybody reading my advice here or anywhere else on the INTERNET:
The quality of the advice is normally proportionate to the price your paying for it.

just another idea on a gauge mount here. i tapped the front of one of the water in fittings.

make sure you put it togather with high quality plumbing! consider the sinario of a failed hose clamp or blown hose

Originally Posted by EVILFORCE

I never seen a dash water pressure gauge.

I run block water pressure in the dash. AutoMeter Pro Comp Marine mechanical water pressure gauge 0-35 lbs with AN line from the front of the manifold.

http://www.rexmar.com/page60.html

0-35?!? i must be way too high. i hope it was the vibration that knocked my needle off and not shooting above 60psi.