Water PSI clarity question

[Chris1978]

Hey Guys,

Just want to clear something up in my head about the water psi when driving...

I have 20psi at WOT, 6000rpms which I know is safe.

Now what about these..

1) 8psi half throtle, 3500rpms
2) 8psi WOT, 5000rpms but no trimming & therefore speed &rpm is way down?

I guess my question is about WOT and what that really is becuase I can push the gas to the floor, but if I do not add trim then my rpms do not come up and therefore the speed does not come up and therefore the water psi does not either.

So is it better to base water PSI important to RPM range rather than throtle position??

...or I could just be crazy

[CRIMSONGAMBLER]

If you have low water pick-up you have to account for the ram effect also, higher the speed, more water being ramed into the pump.

[Chris1978]

yes I have the sporty with low water pickups.

[450jd]

I have a sportmaster on my 300 and its about 5psi at idle the more rpms the more pressure I get.

[Chris1978]

yup thats the same with me...

I guess thats why I was aking to see if there was a water PSI range rating for RPMS vs the old "AT WOT YOU NEED xxPSI"

Just something more measurable I guess.

[EuropeanAM]

Water pressure "minimum specifications" are only given for IDLE SPEED and WOT.

This is due to the fact that different setups will vary IMMENSELY in the mid-range.

Before we get into the spec's, let's "define" what we're looking at:

Idle Speed: This should be obvious. No throttle applied with engine running.

WOT: WIDE open throttle, propped within the recommended RPM range for the engine, with the trim set at the appropriate height for operating conditions. In your case, this would mean a trim angle that allows for at least 5500 RPM's.

Now the specs:

Idle: 1-3 psi
WOT: 15 Psi MINIMUM (prefer to see 18+ psi for safe measure).

As for anything between idle and WOT, "your results will be between the idle and WOT specifications".

[Chris1978]

Thanks very much !! Thats what I was looking to understand.

My biggest concern was if I had my foot to the floor (WOT) but was only at 4500rpms (because I had not not added any trim) therefore only getting 8psi. But with your input now I know that this is safe.

Thanks again !!