That explained a lot, Reed. I'm freshwater, didnt know you were salt.

Another point is twin vs.single turbine set up. 2 smaller turbines vs. 1 honker footwide Banks, twins are better. The little wheels spool so much faster and make the same boost. Just, way more bucks for the exhaust fabrication and dual inlets on the intercooler.

robyw1, when you speak of watercooled intercooler, where would you get the freshwater(separate pump?), and couldn't you T off of that for cooling the turbo?

Most boats that have intercoolers... whether for a turbo or rootes type supercharger get their water from a separate through hull pick-up... just the forward motion of the boat will push the water through the pick-up and through the intercooler.NO pump... just a sea strainer to filter out the debris.

"just the forward motion of the boat will push the water through the pick-up and through the intercooler.NO pump... "

Well...that sounds to me, slow running or idling around...you'll heatsoak the whole boat.

Only the intercooler is plumbed that way... it is a seperate system... not connected with the cooling system for the engine.. you really only need to cool the charge when you are boosting the intake charge... as soon as the boat gets on plane.. there is plenty of flow to the intercooler.

I think if I was going to do it I'd run that pickup thru a belt driven pump and pick off it to cool my turbine too.

If my boat was longer I'd be thinking foolish thoughts. Well, I already am.

:)

KHO.... at speed.... the pump would impede the flow of the water... generally the turbo is cooled last along with the exhaust after the water has circulated through the block and heads, then it dumps out the stern. We are talking about the same thing... aren't we? Raw water cooling ? Gas engines.... stern drive boats? Only the intercooler is plumbed separately. No reason to have two raw water pumps. You are welcome to plumb it any way you want.... I generally try to keep things simple...

Dyno, I am busy building a drive to hold all that bottom end torque--1000ft/# at 2200. I am putting a Blackhawk lower on a Bmax upper, just about done. The Bmax upper never failed, but the mercury lower gears couldn't't handle the torque.
I figured that if I had two props that should divide the torque by two. I also remembered how fast the boat was with less HP. It looks great, I'll post some pictures next week.
Tom

I had those also. It is a water cooled jacket that fits around the outside of the turbo. That is what was used before they came out with the water cooled housing.

Okay.

Turbos done properly are LOTS more expensive than a blower (from a mfg point of view). Bolt on a blower, rig the pulleys, change the timing and fuel curve, and you're done.

For a turbo, you have different exhaust manifolds, lots more plumbing, blowoff valves that have to be plumbed back into the loop for marine usage, and a setup that is intolerant of fools. Warranty claims? Can you say yikes?

Now, if you are making your own homebrew, it will still be expensive but you can get a great result.

Roby knows turbos, so that is a good start.

You gonna have to use a marine turbo - water cooled ball bearings and full cast water jacketed exhaust section. Big bucks unless you can work around the lag of a diesel unit (they typically have a lot of inertia). You WILL have to run an antifreeze mix thru the housing for best results, and that entails another heat exchanger. BOV and waste gate will both be necessary if you plan to run it in rough water where you need the response fro the sticks.

Can it be bad-ass? Definitely, butyou gotta properly deal with the heat and corrosion and inertia.

I'd advise finding a diesel boneyard and getting heat exchangers, aftercoolers, and water cooled turbos from them to experiment with. You'll want twin turbos cause with marine exhausts you can't get the turbine very far away from the ports or you lose all of your heat energy..

Have fun.