Cooling dry turbo exhaust manifold

Engine: 2005 BHW VW 2.0 TDI
Boat: 1988 citation 22ft 8 cabin boat
Outdrive: volvo penta 290
Full electronic control. Throttle by wire. Malone tuning will handle converting the ecu over and deleting the exhaust sensor. Factory 05 passat wiring harness will be dumbed down to only necessary wiring/relays. Stage 2 tune, 170hp and 300ft lbs torque. Sweet torque range is 1900 to 2400 rpms. Not sure if i should plan on foot change for gearing or keep stock v8 single prop

Boat is sub 4000 lbs dry. Hull very simlar to a bayliner cierra cabin cruiser or searay cabin cruiser of same vintage.

Engine compartment is very large. Nearly 4 ft deep, over 6 ft wide and 5ft for to aft.

Biggest issue is cooling, im spit balling some ideas, hope you guys can give insight. Ive done many a diesel conversion, never on a boat.

Just like on a vw 1.9 tdi the intake/exhaust share the same side of the head. One off water cooled.manifold presents both cost and engineeting issues. First is space second is tuning and turbo perfomance.

Air cooled? Box in the intake and exhaust. Use a box within a box(double walled) like a chimney pipe( emtpy air gap or fill with insulation?) Pipe in cool air then use 2 large 4 inch bilge fans to pump out hot.

Possibly also use fan in intake for forced air?

Also possibly use a heater core as a heat exchanger inline of the charged air to cool. This can be plumbed into engine heater core line (190 ish temp) or I'll be running a 2nd raw water pump to pump water for a small modified power steering pump heat exchanger for cooling the water to air intetcooler. This would run the same temp as the surrounding water. 68 to 90 deg depending on time of year used. Although 95% of use will be fresh i need closed loop cooling for the motor anyway so salt water won't matter.

I plan on adapting the factory aq211 crank drive raw water pump to run raw water to a v8 heat exchanger. I may not run it directly off the crank but will run off of the motor.

As for the 2nd raw water pump, ill use electric or pump driven depending on cost. I prefer to keep electronics to a minimum. The boat has a small cabin so i may even retain the ac to run cooling in the cabin while underway.

Still gotta figure out plumbing single exhaust into the volvo y pipe. Have yet to pull motor to see if i can remove it and replace with single. I will be injecting water post turbo.

The idea is to keep engine bay sub 200 degrees. More boat time less burn center time.

Adapting my gm marine power steering pump which is a v belt to my. Serpentine driven vw is a other hurdle but small one. I dont think i can revalve the vw ps pump like i can gm, would love to.

 

Ducted air cooled with a fan will be your cheapest easiest solution. VW did not design the metallurgy of their CAR motor to be immersed in water, fresh or salt. You'd be asking for major costs and headaches.

 

Ill 100% be using a closed loop systems. The only raw water in the system will be from raw water pump to heat exchanger to downpipe post turbo.

The 04-05 diesel passat had a mechanical cooling fan, clutch driven and a smaller secondary cooling fan for the a/c. For anyone attempting this that factory elecric fan is very problematic and unreliable but yes i can see how a small electric auto fan for eBay/junk yard will be cheap and reliable.

Do you feel it will be cool enough in the engine bay?

My daily driver BHW diesel passat has over 220,000 miles. When i did my auto to 5 speed conversion i deleted the balance shaft as well as installed new timing belt/water pump. On most American vehicles this iron block cooling passages are rusty or tarnished. This car had always used demineralized water and vw/audi pink coolant. It was clean as new inside. I will 100% be using closed loop cooling.

 

Should be fine. You said the bay was like 120 ft^3 right? A couple of good sized louvered vents in the roof hatch with the forward one with the duct and fan directing it onto the engine should be enough air flow to prevent it from turning into an oven. You would have convection working for you, which you really don't have in an auto.

The cooling passages are designed for it, but a one-off external cooling jacket will be a PITA to work around I think.

 

Yes. The hatch opening is at least 4ft by 4ft. The compartment is flush with cockpit floor