How To Increase Water Pressure/Flow?
 

I have IMCO 1" shorties with XR Drives. My water pressure is 5-8 lbs at 70 MPH. Oil temps are high with thermostat installed, but water temp is less than 100.

Hoses and impellers replaced. Backflush complete.

How can I increase flow to acheive 15-20 lbs at 80 MPH?

Thanks, Chris

Add a thru hull water pick up.

Did you replace the seapump housing/body???? I would try that if you haven't. Also is it a merc impeller. I have heard of several Sierra brand impellers that wouldn't suck water.

You should be getting more water psi at 70mph than that with just the pressure created by moving through the water and forcing it into the drive.

When I added 2" shorties I couldn't get enough flow, so I had to go back in and add 1 1/2" spacers to get the drives low enough to pick up enough water. This stuff is all trial and error. This is on a 28 TD Daytona with no boxes.

Right now I'm having the complete opposite scenario with my port engine having too much pressure and blowing water out the 496 pump valve at higher speeds.

Hey Chris, what about making the opening a little larger.....

Usually with Imco lowers the issue is too much water pressure. Are you sure that there are no restrictions anywhere or that you have a sound water pump as Griff had mentioned??

How far are you trimming out at that speed? Imco lowers don´t like to be trimmed out very far before the water pressure tails off.

If you have inline oil coolers I would pull both the top and bottom water hoses off and shine a light through it!

Found mine PLUGGED with little pebbles and wood chunks :(
Took a lot of work with many coat hangers to get them cleaned out :( But at least I did get them cleaned.

I know you said you backflushed already, as well so did I many times.
However there was way to much blockage to get those pebbles/crap out.
Very well worth the look!
I know that is what I will be taking apart first before back flushing in the future!