Nordicflame

iTrader: (4)

Does anyone know the real answer to the water pressure issue?
Searching all of the previous post it seems that the desired water pressure is approximately 5 lbs at idle and 22 lbs at WOT.
So I’ve been banging my head against the wall to achieve this the best way with my ProCharger setup. You guys have been very helpful with suggesting ways to achieve this.

Now I’m confused………I read a post in the general discussion threads called “496 goodies”, and there is a statement that says:
"With all our systems, we stress water pressure, we even have a Mercury Racing bulletin that states the same, they want a minimum of 25lbs. and maximum of 35lbs. @ WOT on all of their engines no matter what"

What gives here????????????
Thanks in advance,
Dave

Panther

Nordic,

I would assume your problem is too much pressure?

From what I know, there are several ways to limit your water pressure.

I had to do it on a Cigarette once a long time ago. The thing was making tons of water pressure. All we did was put an extra bung in the Headder tailpipe, and ran a hose to a fitting which pumped the water out the side of the boat. It was actually kinda cool, cause you could tell if you had watter pumping by just looking out the side of the boat. Just make sure you put the bung on the top side of the tailpipe so that you don't have hot spots in the pipe.

Another way I have seen it done if you have too much pressure is to put a bleed off valve in the water pressure hose. Outerlimits does this. Its a pretty simple system, and you have total control over exactly what you want your water pressure to be. I didn't look at the boat to figure out exactly how they plumbed it, but is should be pretty easy. Maybe someone here on the board has an Outerlimits and can give some pointers.

Nordicflame

iTrader: (4)

Thanks for the reply Panther...
I don't have a problem yet though; just trying to avoid one when I change over.
I would just like to know what pressures we should all be trying to achieve. It seems like their is some very conflicting information on what appears to be a very important aspect of these high performance engines.
I figured this would have a lot of response with all of the previous posts thier have been on this subject

The general concensus on the board is 5 at idle and 22 MAX at WOT.
Mercury Racing is saying minimum 25 and 35 MAX at WOT???

Thanks,
Dave

blown formula

You will have with the Procharger or any other intercooled system, a slightly lower pressure due to the water dump of the intercooler. This has not been a problem with any of my boats with PC's. There is no thermostat in a PC system so the water flows quite freely......never more temp than 130 degrees water temp. Plenty of pressure thru the exhaust, cooler, etc. All normal original Merc plumbing. Ask yourself this - If water pressure is so critical to be between 22-35#, why does Merc NOT install a pressure gauge?.... They are worried more about temperature than pressure....after all insufficient pressure leads to excess temp..... with the PC intercooler water dump installed in the drivers SIDE of the hull, you have a constant visual indicator of pressure.

Turbojack

I second what blown formula says. Only time I saw my temp up to 140 was after I restarted motor ater letting sitting for few minutes. Most time 100-105. Unless you know you have a jproblem of some sort I would not worry about it. Too many other things to worry about.

In an automotive system the pressure cap is 15lbs I think, So Why "Mercury Racing bulletin that states they want a minimum of 25lbs. and maximum of 35lbs. @ WOT on all of their engines no matter what." Only reason I would know why is to keep steam pockets from forming when running hard.

WETTE VETTE

Really you want as much water pressure as possible to raise the boiling point and remove steam pockets, as Turbojack has mentioned. The problem is intake and head gaskets will leak if to much presure is applied. I think 18 to 22 psi is a good compromise, especially if the boat is fast and pressure spikes may occur. If you run 35 PSI and get a spike when re entering at 100 MPH there will be a good possibility of a leak occuring and milky oil. As far as low RPM running 5 PSI is plenty if the temps stay down.

MIKEHTMSR24

My water flow system by Gary.

540 ci N/A
Thermostat ( 160* @ idle and 140* any other time)

Water pressure relief valve by Grimes (7 psi @ 1000 r's and 18 @ 5600 @ 85 mph) This has a 1" ID dump @ transom that dumps water on drive All hose from sea pump to motor including valve pluming is 1.25".

360 hrs. no problems

Inside tip: If you are running a crossover. More than likely you will have more water flowing into on head than the other. For cure call Gary
Just kidding. Take a gasket from the crossover and make a new gasket out of a thin sheet of stainless steel. Do not cut out the water inlet hole in the new gasket. Instead drill a .4375" hole. (7/16") Put this new plate on the cold head (put another crossover gasket behind). Get an IR gun and compare head temps between the two. Open up hole as needed to get heads equal.

Tantrum

Excellent question. I think Im running way too much pressure at WOT (30+) but have not come up with a way to bleed it.
I also havent been able to get a clear answer on were it should be. Dustin as I recall said to run it on the Higher side. I dont remember what the actual number he called for, hopefully he will catch this post.
Im running a littly modified 502mag NA.

Why am I thinking a gaffrig gauge only goes up to 30 ???

WETTE VETTE

I have installed this valve on numerous boats that were having high pressure problems and have had no problems getting them down to that 15 to 22 PSI range. It installs by putting the stainless tee into the main 11/4 water pressure line before or after the oil cooler and then running a 3/4" heater hose from the tee to the adjustable valve, and dump it overboard. I have a few of these and can sell some as pictured for $110.00 plus shipping. It is a good idea to run a sea strainer before the valve to keep contamination from plugging up the valve. If crap does get lodged in the valve it will shut off and water pressure will go up to where it was before the valve was installed. The valve would then need to be cleaned by back flowing water or air through it. I haven't seen this happen on any of the ones that are out there that we are trying. Here is a photo of the valve and the stainless tee.

Turbojack

Getting off topic for a second

WV - I like that 1 1/4 pipe with the takeoff. I was looking for something like that to install right after water pump so I can get the coldest water to my intercooler. I have used my IR heat gun & have found that the water temp increaseds 4-6 degrees before it gets to the intercooler going thru the fuel, motor oil, & PS coolers. Not sure how big a difference the 4 degree makes in total HP. but every little bit helps.


Now back to your regular topic!