Merc Racing 400R Water Pressure ?

[instagator]

Wide open throttle, 7000 RPM. Whats the lowest water pressure before the alarm goes off ?

 

[blue wonder]

Kinda seems I’d your asking that question you should probably just change the impeller

 

[DarkHorseRacing]

Wide open throttle, 7000 RPM. Whats the lowest water pressure before the alarm goes off ?

A Google search says the 300r is 8psi min at WOT but the advice is 15+ psi (like 18) to cover yourself during turns etc or it goes into Guardian mode

Now that’s the 300r but no reason why the 400r wouldn’t be similar.

 

[DarkHorseRacing]

Also supposedly if you plug the side holes and use the lower ones you can build better water pressure.

 

[instagator]

Trying for max engine height for speed, My impeller is good.

 

[McKay]

I would shoot for high teens. However if it were me. And yes this is exactly what I have done is keep raising till too high then drop it back lower. Only takes 10 min on the ramp if you have a buddy helping. Couple hours on the water testing with a buddy you can try 4-5 different heights. Our current boat 20thousands is the difference between plenty of water and not enough.

 

[n2otoofast4u]

If I don't see low teen PSI at speed the temp creeps up and with sound the alarm. If I catch it creeping up, one bump of the button and the temp comes right back down. I am 3" above bottom at 100mph. If I run it HARD at "normal" level, the damn thing makes high 20s PSI and it worries me. I have a happy medium spot, but its fun to play with it.