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Thread: Lack of water pressure HTM with IMCO lower..

  1. #1
    Not being very familiar with cats I've run into a dilemma.
    I have installed a Whipple on a 502Mag in a HTM SR24. We also installed an IMCO lower for water delivery to both the motor and IC because HTM says they do not advise any type of transom or thru hull pick up.
    We've installed the restrictor plate from Whipple and everything else seems normal except we are only seeing 10-12 lbs at 3000 rpm and then it actually drops to 7-8 at about 4000. We stopped there not wanting to take any unnecessary chances.
    Is this a normal circumstance or should I look for a posiible problem elsewhere?
    On my V this setup produce excess pressure that I blow off at 25 lbs.
    Any insight would be appreciated.

  2. #2
    don johnson
    Your water pressure at 3,000 is normal. However, with speed WP should pick up. I would speculate that your x dimension is high enough that when you start to accelerate the water inlet at the bullet is either coming out of the water or is receiving highly aerated water.
    I had this happen in my Daytona when I switched to a 2 inch shorty lower. I added a 1" spacer due to water pressure and prop ventilation which fixed both problems. I now run about 15 psi at 3,000 and run about 27 psi at 6,000

  3. #3
    X dimension is assumed standard and HTM says not to shorten it.
    Anyway, the drive is a one inch shorty with a 1" spacer.
    Guess I'm gonna have to poke around :idea:

  4. #4
    how does the water flow from the drive through the transom? I once had this same problem and found the hose was getting twisted and resricting the flow.

  5. #5
    Bad Puddy Tat
    I had this same problem on my SS24 I finally went to an external pickup in the sponson and all my issues went away. I'm not sure who at HTM told you not to do an external. Jim Wilkes did mine and I know he was talking with Roy up there at the time it was done. I've been running that way for 2 years now with absolutely no water pressure issues.

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