hmmmm marine motor

[Diesel JD]

The 289/551 is nothing to write home about at the crank. If that were at the wheels that would be pretty snappy. You said at the wheel, I assumed you meant flywheel HP if not my mistake that's as good as the stock and lightly modified 7.3 PSD. If you meant at he flywheel then figure a 30% parasitic loss in the drivetrain so 202/386 still really good but I bet you can easily throw down those numbers all day with a Moose or similar pump, Moose Misters, an intercooler and any turbo. Travis was there with the E and Darrin was there pre Cummins conversion with a 7.3 turbo IDI. I wonder what pump is on that 7.3 marine diesel. If that turns the opposite way that means it can use the GM DS4(electric/mechanic) or all mechanical DB4 for 6.5 marinized diesels.

 

[kas83]

The 289/551 is nothing to write home about at the crank. If that were at the wheels that would be pretty snappy. You said at the wheel, I assumed you meant flywheel HP if not my mistake that's as good as the stock and lightly modified 7.3 PSD. If you meant at he flywheel then figure a 30% parasitic loss in the drivetrain so 202/386 still really good but I bet you can easily throw down those numbers all day with a Moose or similar pump, Moose Misters, an intercooler and any turbo. Travis was there with the E and Darrin was there pre Cummins conversion with a 7.3 turbo IDI. I wonder what pump is on that 7.3 marine diesel. If that turns the opposite way that means it can use the GM DS4(electric/mechanic) or all mechanical DB4 for 6.5 marinized diesels.

At the wheels = chassis dyno.

 

[gatorman21218]

But the trick is how do you dyno a boat? Also IIRC boats with twin engines have two engines running opposite ways. For example the port engine is spinning clockwise while the starboard will spin counterclock wise. All marine engines are rated at a higher level than their highway brothers. The 671Ts we had in our boat were rated at 450 hp but the on road is about 250 hp. Bigger injectors, constant rpms and endless cooling water are the main reasons why

 

[VanBoy]

Interesting.

On a marine engine, are they running "radiator/engine" coolant into the turbo/manifolds? Or are they running filtered "sea" water?

If one tried to put a marine engine into a truck, I don't think there is a radiator big enough to handle cooling all of the heat the turbo/manifolds would transfer to it...

 

[gatorman21218]

On a marine engine instead of a radiator there is a heat exchanger. reg ol' coolant runs through the engine and through the exchanger where raw water flows through absorbing the engine heat. raw water on a heat exchanger is what air is to a radiator. Well if you found a radiator the size of a lake you could do it

 

[jwalterus]

Well if you found a radiator the size of a lake you could do it

throw a 1000 gal water tank in the bed of your truck and stick on a heat exchanger?

forget the fact that you'd be hauling an extra 8-9k lbs every time you ran, that won't affect performance

 

[gatorman21218]

throw a 1000 gal water tank in the bed of your truck and stick on a heat exchanger?

forget the fact that you'd be hauling an extra 8-9k lbs every time you ran, that won't affect performance

How bout just a tarp in the bed and fill it with water? doubles as a swimming pool

 

[snicklas]

Actually on a boat, they have both closed and open cooling systems.

A friend of ours has a MerCruiser 4 or 6cyl I/O that is a closed system. There is a large heat exchanger on the topside of the engine, There is regular old green antifreeze that runs in the block, just like in a vehicle application, and seawater is drawn in thru the lower unit and run throught the heat exchanger, and the exhaust manifolds I believe, the cooling water in the manifolds are not in contact with the coolant in the engine.

On Dad's boat, it is a 350 Chevy I/O with an open system. Seawater is drawn in thru the lower unit and passes throught the waterjacket in the block and also thru the manifolds. The engine to drive hub failed in his boat a couple years ago, and we could not winterize it by submergine the lower unit to fill all the passages. We opened all the drains in the block and drained all the water that would come out. We then started removing hoses off the top of the engine and pouring in pink rv antifreeze into the hoses until it ran out throught the drains. Once we did this and had all the drains closed, the pink antifreeze ran out throught the water intake and exhaust ports in the outdrive....

 

[The Warden]

Also IIRC boats with twin engines have two engines running opposite ways. For example the port engine is spinning clockwise while the starboard will spin counterclock wise.

That depends on the engine. A 6-71 (or any Screamin' Jimmy) can be easily made to turn in the opposite direction, so usually on twin-screw Detroit-powered boats, the engines themselves are spinning in opposite directions. On other engines that can't be easily made into a reverse-rotation setup, there's typically a reverser gear in one of the transmissions, so that the engines are both spinning the same way but the screws are turning in opposite directions.

FWIW I can't recall EVER seeing a twin-screw boat where both props were spinning the same way.

Regarding open and closed systems, I think that most smaller boats (especially boats meant for fresh water and boats that are trailered) have open systems, and most larger boats and ESPECIALLY boats meant for salt water have closed systems. I've also seen some fishing boats out of the water that had heat exchangers under the hull. Instead of pumping seawater into the boat, it ran fresh water into pipes that snaked along the bottom of the hull just above the keel. I'd hate to run aground in one of those

 

[snicklas]

Regarding open and closed systems, I think that most smaller boats (especially boats meant for fresh water and boats that are trailered) have open systems, and most larger boats and ESPECIALLY boats meant for salt water have closed systems. I've also seen some fishing boats out of the water that had heat exchangers under the hull. Instead of pumping seawater into the boat, it ran fresh water into pipes that snaked along the bottom of the hull just above the keel. I'd hate to run aground in one of those

I agree on the type of water they are used in. The 2 boats the I referenced are both "trailer boats" The closed system in is a late 80/early 90 19' Dynasty Open Bow Runabout and the open system is in Dads 87 23' Sea Ray Open Bow Runabout.... Both MerCruiser and I believe both Alpha I or Bravo I outdrives from the same era...... I know that winterizing the closed system is much easier..... no plain water in the block.......

 

[Agnem]

EGT's are going to be the limiting factor in any application. Engine cooling is obviously a lot greater in this app, but pistons still melt at the same temp, truck or boat. My bet is the higher HP rating comes from running at full boost with a non-wategated turbo and water cooled manifolds. The intake air is always going to be cooler (look at the tiny air cleaner... no dust at sea). Any road ready IDI that can push 12 PSI and maintain it's engine temp will make the same numbers. The problem is a chassis dyno measures HP as torque over time, and you have 100% contact between the tires and the rollers. To rate a marine engine, you need a water load on the propeller, and that's going to act like a torque converter in an automatic, and as we all know automatic trans make more HP thanks to the torque converter working as a torque multiplier. Then again... I'm just wetting my finger and holding it to the wind here.

 

[gatorman21218]

Warden - maybe I was over generalizing but your correct in that some motors have a gear in the tranny that spins them the opposite way, but the detroits can and do spin opposite. And yes outboards are a good example for open systems. Water is sucked up from an impeller and goes through the block and is "peed" out. Heres an idea mount an IDI as an outboard

Mel- i will disagree with the air filters being smaller due to no dust at sea. Engine rooms are not "operating rooms" and have just as much dust as any other place. Granted there is no dust from the roadway but there is still particles floating around. For example salt from ocean spray, dust from belts and hoses, oxidation/rust from anything metal and if you have a golden retriever, lots and lots of pet hair. Its going on 5 years since we sold Legacy II (Atlantic '47 with twin DD 671T) but I can remember a large air filter that looked like a K&N Cone filter. Also the engine room got to be around 120 degrees with the only fresh air coming in from side vents. Going from the bridge down into the cabin while under way you could actually feel the suction on the cabin door. We would wait 4 or 5 hours to open the engine room cuz it was so hot. (gotta love them detroits! took 2-3 qts of oil every 3 hours running) I would think a truck would have cooler air flowing around the engine at highway speeds

 

[VanBoy]

The WHAT IF's ......

If one could shoe horn this engine into a truck as is, with the water cooled manifolds and turbo.... a few questions.

With out getting into thermodynamics and all those numbers......

How many quarts does this marine engine run in it's cooling system (closed system) when using a heat exchanger?
How much more "cooling" does water do vs air? As in efficiency?

If one could put a custom multi cored radiator in front on the stock location, more cores then the stock for 7.3L IDI....

AND then make a custom BIG radiator to mount on the bed of the truck. Hear me out. Not sure which way the flow would go (front rad first then bed radiator or bed radiator then front radiator)... Any how, if one could make a custom radiator, say just wide enough to fit inside the bed and as tall (7 feet by 2.5 feet by XX" thick) and put high flow electric fans (4 or 5).... If you can double or triple the coolant capacity of the system.... would that be enough to keep this bad boy cool?

Maybe even add an large oil cooler to the lubrication system with an electric fan on it???? I've seen those "funny" tube type coolers that can be mounted in the frame. If one can keep the oil under 190.....

 

[Agnem]

...
Mel- i will disagree with the air filters being smaller due to no dust at sea. Engine rooms are not "operating rooms" and have just as much dust as any other place. Granted there is no dust from the roadway but there is still particles floating around....

I won't disagree with that, but it seems from the manufacturers perspective they think whatever there is that they can ignore it. All my OMC 5.0L has on it, is a spark arrestor from the factory and the boat I used to have which had a 4 cylinder Chevy based Mercruiser in it was the same way.... no air filter at all. I guess the diesel in the pic is lucky to have one. Maybe they just thought they should cover the turbo opening so nobody could stick there finger in.

 

[gatorman21218]

Yeah i think youre just asking for trouble if you take off the air filter. The few hp you gain is nothing compared to the few grand your mechanic gains when he has to rebuild the engine and/or turbo if so equipped.