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skrenz
03-04-2014, 12:59 PM
I'm looking to power a new power boat project with a Kuboto engine. I need to convert it from an air cooled/radiator model to a water cooled heat exchange model and adapt it to a marine transmission. To do this I believe I will need the following major items:

Raw water pump fitted to the camshaft ?? I believe that this is a Jabsco
Heat Exchanger
Exhaust Riser
Drive plate and housing to mate to a TMC transmission


Yes, you guessed it, I essentially want to end up with a Beta Marine 28. And yes, I have pursued buying a new one or finding a similar used one.

I am fairly mechanical and the mechanics of doing this would be a challenge but not outside of my abilities. What I really do not know about is how to pursue aftermarket products that can fill in the missing pieces. For example, there are multiple heat exchanger companies but I'm not sure what to ask for. Probably the larges question in my mind is where/how I get the piece that adapts the rear of the engine to a marine transmission.

Any help from folks who have done similar conversions would be helpful.
Thanks

slug
03-04-2014, 02:35 PM
I dont know the kubota.

Marine engines have water cooled exhaust manifolds, sea water injected exhaust plus an isolated two pole electric system. Engine oil capacity is often greater. Oil coolers are often added.

its possible that these are just add ons to a standard engine.

perhaps its best to look at a professionally marinized Kubota then record component manufacture and part number

Bowman makes the best heat exchangers.


Look carefully in the VETUS online cat ..the technical section. http://www.vetus.com/sas I believe many of the engines are kubota blocks

also Nani. http://www.nannidiesel.com/general/index.php

Tom Robb
03-04-2014, 04:10 PM
Other than an interesting challenge, why not buy the Beta?

skaraborgcraft
03-04-2014, 04:56 PM
The price of sourcing the parts needed to convert the engine are not going to be far less buying the Beta. Converting older engines can sometines be cost effective like some of the bigger Perkins, but in the small size you really dont save too much unless you have got your donor egine for almost peanuts.

Stiletto
03-04-2014, 05:27 PM
The converted diesels I have seen run their raw water pumps from what was the fanbelt. It would have to be a manufacturer specific pump to run from the camshaft.

donald branscom
03-04-2014, 06:39 PM
I'm looking to power a new power boat project with a Kuboto engine. I need to convert it from an air cooled/radiator model to a water cooled heat exchange model and adapt it to a marine transmission. To do this I believe I will need the following major items:

Raw water pump fitted to the camshaft ?? I believe that this is a Jabsco
Heat Exchanger
Exhaust Riser
Drive plate and housing to mate to a TMC transmission


Yes, you guessed it, I essentially want to end up with a Beta Marine 28. And yes, I have pursued buying a new one or finding a similar used one.

I am fairly mechanical and the mechanics of doing this would be a challenge but not outside of my abilities. What I really do not know about is how to pursue aftermarket products that can fill in the missing pieces. For example, there are multiple heat exchanger companies but I'm not sure what to ask for. Probably the larges question in my mind is where/how I get the piece that adapts the rear of the engine to a marine transmission.

Any help from folks who have done similar conversions would be helpful.
Thanks

You said it is a "powerboat" how large? What design?

It makes no sense to me why you would do that.
Why have salt water going through the engine and all the parts?
Are you going to machine and mount fittings for zincs all over the engine too?

Here is my suggestion.

Leave the engine cooling system as a fresh water cooled engine.
Just mount the water tank for the cooling system inside a metal skeg on the outside bottom of the boat.
That will cool the water in the skeg and return it to the engine.
Mount a water pump off of the belts being driven by the crankshaft to cool the water lift exhaust.

You will have to get that adapter to mount the transmission though.
Anyway it is easy to do.

Make sure the sea chest comes up above the waterline so you
can clean the raw water screen while the boat is in the water.
The Vetus raw water filter is a good design. It has a clear plastic see thru lid.

Lutine
03-04-2014, 07:55 PM
What is type kubota engine do you have? To my knowledge Kubota did not develop its own engines but used Mitsubishi engines. And these were also used for Beta and vetus models. But they vary in number of cilinders and bore.

My boat has a Mitsubishi K3B from '78 and is marinesed by an unknown source. I will summarise how this was set up:
- raw water comes in throug a riser with seacock, filter and cleaning cab just above the waterline.
- the raw water pump is an impeller type, driven by the fanbelt. I think it is a mercury. Most outboard brands have that kind of pumps, just look for one with an easy to obtain impeller.
- the heat exchanger is integrated in the exhaust manifold and the raw water leaves the exchanger in the exhaust pipe, just a bit lower than the manifold, in a standard exhaust waterlock. I don't remember the brand of the heat exchanger, but its the same Vetus uses.
- the fresh water system is led through the heat exchange by the same rubber hoses you would use for the radiator.
- the gearbox is connected to the engine on the flywheel, where you normally have the clutch. I suspect that the marine gearbox will be the most expensive part to buy. If you can secure that part for a good price, your project might be succesful.

I do have schematics of some mitsubishi types, of if you can tell me which type you have, I can have a look if i have those. I think i ripped them from the vetus site anyway.

Cheers,
Azarja

nedL
03-05-2014, 08:19 AM
Nothing wrong withthis if you can get a real good deal on the Kobota. The biggest issue I see is finding a water cooled exhaust manifilold. For the fresh water cooling components I would go to Den-Dure, they will be able to provide you with a 'kit' that is properly sized for the engine (water pump, heat exchanger, surge tank). Yes, to do it 'properly' you may need to look into a new starter & alternator too. The adaper plate for the reverse gear may be something that you have to develop on your own.
Interesting project, let us know how it comes along.

skrenz
03-05-2014, 02:29 PM
A couple of clarifications if I wasn't clear enough in the first post:
Don, I'm not talking about pumping sea water through the engine. I'm proposing and asking about a heat ex-changer and how to find the correct one.

As to the question about Kobota engines and Beta marine engines, the Beta 28 and the Kobota D1005 are exactly the same engine, probably made by the same manufacturer. The Beta is marinesed with a seawater pump, heat exchanger, and bell housing to mate to a TMC transmission.

Why pursue this? Have you priced a new Beta engine lately? I can get a Kobota engine at a third of the cost. The question is, can I supply the necessary parts to marinese the Kobota engine for less over all.

Thanks for the input and ideas so far.

Canoeyawl
03-05-2014, 03:13 PM
Do you need a water cooled exhaust? Plenty of marine engines are "dry stack"

The camshaft driven water pump is typically fastened to the timing cover, and driven by the camshaft or cam timing gear.
So different camshaft/gear and timing cover?

The fuel metering/governor system may also be different then a tractor or stationary engine.
You will need the flywheel/transmision drive spline hub or coupling device to fit your transmision input shaft.

(Rob White did something like this a few years back, but he is dead. There were some articles written in "messing around in boats" about it).

Breakaway
03-05-2014, 03:18 PM
^ As I recall, Rob White used a belt driven shaft. Google his name and "Rescue Minor."

Sent from my iPhone using Forum Runner

Mike Dawson
03-05-2014, 03:56 PM
skrenz
I did exactly as you propose twice back in the 1970's with great results. Back then the only small diesel marine engines were heavy, expensive and physically large. My neighbor had just started a Bobcat franchise (think what he is worth now!) and they were starting to use Kubota engines in some models. I bought a "replacement" engine from him, fabricated a wet exhaust manifold, added a Jabsco water pump and a Seadur (sp?) heat exchanger for a closed cooling system. It came out at about 1/2 of the cost of a Volvo Penta or Westerbeke at the time. The second time I converted a Mercedes Benz diesel engine out of a semi trailer refrigeration unit with the same results.

If I were to do it today I would choose a Kubota engine model that has already been commercially "marinized" (you have done that) and start with purchasing a replacement wet exhaust manifold. This will get you through the hardest part of a conversion, everything else is easy. Access to a machine shop is pretty important.

nedL
03-05-2014, 04:55 PM
I haven't looked, but you might check "Barr Marine" and "Osco Marine" for exhaust manifolds. They are probably the two biggest aftermarket marine manifold manufacturers that are still around.

chuckm
03-05-2014, 05:25 PM
The heat exchanger is the real expensive part. Beta marine uses a Bowman designed exchanger with a overflow and refill cap that directly attaches to the Kabota engine It's the bomb. It also cost a bomb. 1100$. Yes thats correct one BF over a grand!!! Just for a heat exchanger. I'm adapting a a 2 pass coolant heat exchanger made by MONITOR, into a fresh water system. The Beta engine is still just a very refined-marinized Kubota block. I'm going on the theory that any name heat exchanger that has end caps that you can open, ( yes be carefull to ck the gaskets) because these end caps provide access to the heat exchanger copper tubes .Each engine will be different in regards to Zn erosion. I've seen post on Sailing and other sites where guy's have their super Red Beta's and quesss what? Had to exchanger out the heat exchangers. Occasionally you will see the flywheel needed on E-bay. I have that info somewhere and will email you the specific's.

kc8pql
03-05-2014, 05:52 PM
The heat exchanger is the real expensive part.

...and the gear box.

Breakaway
03-05-2014, 06:07 PM
Well, you'd need the gear box anyway, whether its a Beta marinization or a shop-fabricated marinization. IOW, you can buy a "repower" engine w/o a gear. Its the heat exchanger, water pump and exhaust, etc that's the difference ....plus the warranty that one would not likely get with a shop-built engine.

Kevin

TR
03-05-2014, 06:30 PM
These guys might have the manifold kit and riser http://catalog.orcamarine.com/viewitems/marine-cooling-system-kits/manifold-marine-cooling-system-kits?&bc=100|1001

Why not price the gearbox adapter from Beta and/or Nani? On the other hand a good fabricator could build one, it just needs to mount the gear on one side and the engine bell housing on the other, with space between for the correct damper plate. A machinist can mount the damper and couple engine and gear together.

Ben Fuller
03-05-2014, 07:22 PM
What kind of boat was the good question..... there are plenty of modestly powered working boats out there with keel coolers. Simple, cost effective, user fabricated.

skrenz
03-05-2014, 07:36 PM
I've actually thought about going with a keel cooler. What is holding me back from this approach are two things:
Sizing it correctly
Figuring out where to place it on the hull

On another point, it occurs to me that I left out the need to replace the exhaust manifold. The Kuboto of course has the typical exhaust muffler type. Any ideas on where to source this from?

WoodboatCoop
03-06-2014, 12:04 PM
I have just finished my skiff and the next boat will be a inboard to work crab pots. I work at an ag dealership that sells Kubota and have a D902 motor at the farm for the project. I have looked at White's rescue minor set up. I like the idea of a keel cooler. I have found some sources of small drives off of sailboats that I will use. Some Kubota applications run the drive line off the balancer so there are balancers with bolt bosses for easy fabrication. I have seen many ideas of powertrains to modify for marine use but it looks as though a drive from a sail inboard is the least complicated to use if you have the room. The Rob White setup is smaller and would be lighter, which would have its advantages. A side note, Kubota parts are a whole lot easier to get. Also they are used in different makes of equipment, so you might find that application would provide you with different brackets that you might need. Please if you have pictures, share.