You will have to be sure the fitting in the strainer going to the intercooler is below the water level in the strainer so the pump doesn't suck air at idle. You can do that as long as you have a sufficient amount of water volume feeding the strainer. I've done it in the past and the only issue that I had was that there was some water that flowed through the intercooler at idle. I guess there was a small amount of pressure in the strainer at idle so it forced some water through the cooler. I wasn't crazy about that so I just add a separate pickup.
Eddie

Cool thx. Also is there a better belt driven pump for more pressure and movement of water. This is a roots blower so I don't want any heat problems at all. Also this might be a dumb question but what about two oil coolers instead of one since the oil gets hot as heck in a boat especially a blown engine.

I like the tunnel idea and we can do that at my shop. I do that fiberglass for a living and paint boats, working on a 44 mti right now that got hit by a sign. I own fibertek marine on grand lake.

There is no need to go to a 2 stage pump unless you have a pickup larger than 1 1/4". It won't flow any more water. The Hardin pump is a nice piece. The water passages in and out of the pump are larger and smoother for better flow. I'm sure one of their pumps will flow more water than a Merc pump with a plastic housing.

Negative on the 2 coolers. One larger cooler will be more than enough. How much power? If it's less than 1000 hp, an oil cooler with a bundle length of 3" x 18"-20" should do fine. That's not the overall length, but the length of the bundle of tubes inside the cooler. You will need an oil thermostat or you will have problems making enough oil temp.
Eddie

Ok I have all that . I believe it's a little bigger also. So good news I guess. I used to drag race with the I.h.r.a. And learned a lot from those guys but this boat stuff is a little confusing. I bought a callies magnum Xl. And want to protect it the best I can if you get my drift. Expensive but the crank is nice enough to hang on the wall.

Thank you for the info Eddie , very informative as always!
Btw , got any whipple intercooler cores laying around you wanna get rid of cheap ???
I`m starting a new intercooler charity...its for the CHILDERN.. mine wanna go fast!!

I had a few of them but I recently sold them. You are about a month to late. I can certainly get you a new one less than anyone else. However, I will keep my eyes out for a used one for you.
Eddie

Eddie, Icdedpeepees picked up some Lee intercoolers, with leaking cores. Whipple makes a core for them don't they?

I sent Eddie a PM Mild Thunderer with that info

All I got for you is if you ever go in salt warter.... every time you stop or go slow. All of the water runs back out of the cooler and it will be dry , (saltwater damage happens to do the most damage in the first moment is is dryed off.. Probably what those coolers you have need cores). you might be able to check valve it. But check valves can leak and cause some what a restiction. If you run carbs, seperate pick ups are your only choice. IBut if you have fuel injection you can run off the pumps and save bastardizing the hull of your boat. . .. Merry Happy Holiday's !!