I have Imco Shorties on a 35' fountain. After the 1st run I had 60 psi of water pressure at wot. I bought the Merc bypass valves and am now running 30psi at wot. As I come in and out of the water it spikes up to 35 psi.

I was told to run around 20 psi at wot. What are you guys running for water pressure at wot? Is 35 psi to much? I don't want to start lifting head gaskets.

Thanks in advance
T.J.

Try a Globe Blue Impeller from www.Boatfix.com
It is of a softer more plyable material than stock. I ran one and never exceeded 25 psig at WOT. 7-8 psig at idle. This was on a Supercharged motor with crossover that has bypass. Before the Globe Blue, I had water pressure issues.
I am going to run the same setup on my new N/A 540. It is a good starting point. I will post results.

RLW,
Do you find that the blue impellers last longer than the black rubber ones? I would like to put these in the SeaRay and want something that will last. Thanks for posting the website for them.
Robert

Thanks for the input.

Stock 502 Mag MPI. 15-20 PSI WOT. 7-8 PSI Idle. Your pressure seems awful high!

Do you have a p/n for that impeller? I can't find it on the web site.

For the Globe Blue GRW2000 impeller, call Les Hall at BoatFix at
561-848-0193.
He could steer you in the right direction.
Good Luck!
Russ

I used a -10 pop off valve to keep the pressure at 18 at WOT. You can plumb it into the main water supply between the the oil cooler and the cross over. I never had any problems with temperature or head gaskets.

I am running a pair of HP500's with Bravo I's at idle I have 1 to 2 psi and at WOT I am in the 15psi range. Am I out of spec? I never have heating problems. Extended idle it is in the 150 range, and at WOT maybe in the 165 range.

Go Big,
When was the last time you looked at your impellers?
Those numbers seem low to me.
Russ