txriverrat2001

I've heard for years that intercoolers should only flow water when the boat is on plane - not at an idle. Something about the "puddling" of fuel.......The Hemi's are set up so that the water pick-ups in the drives feed the intercoolers and the engines have separate pick ups. I have a friend with a Skater who has removed the pick up scoops and was thinking of pulling water from the sea strainer that feeds the engine raw water pump. He has hull pick ups on the transom. My question to him is whether it will have enough pressure running at speed to produce water - or will the raw water pump be pulling a vaccum that will restrict the flow and/or cause the raw water pump to suck air via the intercooler circuit. A check valve of some type would correct the raw water pump getting air - but will this set up produce the water flow needed for the intercooler?

Any input would be greatly appreciated!!

Capt Ross

MOBILEMERCMAN

Capt. Ross, At what speed are you operating? At 100 mph there is 144lbs of water available in the strainer. Size of the intake hose will help determine volume. Generally once the boat is on plane back flow is not a problem. His set up will probably include dumps to purge off air and even help reduce pressure. Off plane the pump with draw the easiest path so it may draw air if its available. Drag associated with water intakes at speeds under 70 mph is hugely different than over 100mph. There are many ways to plumb inter-coolers everyone seems to have a different preference. I personally prefer not to use check valves for they add a possibility for failure.
Jim

txriverrat2001

The boat will run in the 140 range.32 Skater with 1200HP ..... I agree with the check valves - one peice of trash and at idle you'd probably cook the impeller due to the air being introduced vs. the water.

Should he go back and put the water pick ups for the intercoolers back in? I think he should.

What about the puddling of fuel? - Is that a true scenario?

Turbojack

I have used the water right after it leaves the engine raw water pump. I never had a shortage of water. I had to add another water bypass with the mercury 25lbs pressure regulator to divert even more of the water. Since I have had a blown motor since the 70's I never had a problem with running the water thru the intercooler all of the time. Of course our water down here never get that cold.

Getting water from the outdrive you will need to watch and make sure you have enough water from there if you have a high X. Have a friend that would have very little water flow coming out from the outdrives. Starve the intercoolers of water when motor is at wot might mean melt down.

MOBILEMERCMAN

Like Turbo Jack I have tee'd at the inlet side of oil cooler. When cooler is mounted across the back its a clean rig to run to inter-cooler Ive used a 5/16 washer in the adapter to a # 8 hose and dumped over board where you can see from helm. That set up with hull pick-ups and strainers gave 21 -23 lbs at motors and 8-10 at inter-coolers. 96 mph non step v. The faster set up your talking about would have plenty to purge air and dump at strainer with a # 8. the strainer dump should be under water off plane. I have seen check valves fail and kill motors in race boat and don't care for them. As you know there are many ways and preferences
Pick ups drag a lot of speed from 100 plus mph boats. Its better to scoop as little as possible. Good Luck,
Jim