Kubota Diesel a long term project.

FRANK'S

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I tell you this like it is. I'm a auto mechanic heavy equipment mechanic race car builder and race engine builder.

I have a Kubota diesel engine a D902 with 100 hours got it from my local Kubota Dealership.

25HP @ 3600RPM
130lbs
3 cylinder.

my first mods will bring power to 37HP @ 3200RPM
bigger injectors, pump work,Pump timing advance,
porting and deburing, 5MM over piston and rings.
ARP head studs and con-rod

this is not enough so more mods
some weight reduction I will even grind the block
to take all the OZ off that I can.

install Turbo with inter-cooler and run at 12psi to 15psi
Diesel engine loves air but there is a limit.
this will give me 55hp @ 3200rpm and 60HP @ 3600
now the torque 130lbs torque with 1.5 or 1.6 redrive.

this will be tested in a snow mobile for brake in and reliability.
this will be tested for many hours to make sure it's solid and reliable.
after I will install it in a small Gyrocopter

this is a low compression engine 18 to 1 is low for a diesel so turbo is not a problem.
Modded tractor pullers Run over 100HP in this block and don't have problems.

don't forget this is a long term project. Probably 2 years.

so you guys think it will fly good like a Rotax 582 or be useless.

post feed back good or bad all info is useful.
 

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this will be tested in a snow mobile for brake in and reliability.
this will be tested for many hours to make sure it's solid and reliable.
after I will install it in a small Gyrocopter

Snowmobiles (all land vehicles) use power in a very different way than aircraft. They use high power settings to accelerate and then cruise at much lower settings, similar to a car. They also start and stop much more frequently An aircraft, on the other hand, will takeoff at 100% power for 5+ minutes to get to cruising altitude and then reduce power to ~75% for cruise.

Sorry to say, but it won't be a good test of the engine's performance in your aircraft.
 
it will be a good run in. and there is a old train track that are over 100 miles long and you can run wide open on them.

after snowmobile test I will build a test bench to bolt engine on and do my test.
after snow is gone.

I know i have with my other snow mobile.

I forgot to mention this engine is 100% duty @ 3600 rpm 8 to 10 hours a day.

thanks for your reply.
 
Go Frank, go !!
I am VERY interested in your Kubota test.
My tractor is a Kubota, but it is the 4-cylinder variant and doesn't run wide-open.
Will you be using diesel or Jet-A for the fuel on this test? I know that diesel will be easier to acquire, but perhaps you can test both and see if there is any performance difference ?
I would like to know the final, ready-to-run weight and what PSRU that you will be using. Don't diesels have a more harsh power spike per cylinder?
Thanks for posting this alternate engine thread.
Brian
 
If you want to test it without flying put it on an airboat and run it in deep water, four feet or more, in very shallow water you get the same thing as ground effect and the power can be pulled way back, it sounds promising, I have thought about using the parts from this engine to build a four cylinder two stroke radial diesel.
Norm
 
If you run jet fuel in a diesel you will lose 25% power, where I live you can't buy diesel, the only thing you can buy is jet fuel so all trucks boats and generators have 25% less power than the book says it should, to increase pump life we add a quart of oil to 50 gallons of fuel.
Norm.
 
Very interested in this frank, I am obsessed with those 3 cylinder Kubota engines.
Proper tough little engines 10,000 hr engines don't let there size fool you!
I have been waiting for one to come along at the right price just to play with, just keep thinking they will do so much better than the numbers on paper suggest.
Love the idea of some sort of diesel for a helicopter, Q governor could be perfect.
Was also going to say Jet fuel has less lube in it, needs oil added to save the pump.

wolfy
 
Complete 160lbs but I got mine at 130lbs and will cut the flywheel and grind the block and head of all parts and brackets I don't need.
 
Very interested in this frank, I am obsessed with those 3 cylinder Kubota engines.
Proper tough little engines 10,000 hr engines don't let there size fool you!
I have been waiting for one to come along at the right price just to play with, just keep thinking they will do so much better than the numbers on paper suggest.
Love the idea of some sort of diesel for a helicopter, Q governor could be perfect.
Was also going to say Jet fuel has less lube in it, needs oil added to save the pump.

wolfy

Yes I worked at Kubota dealer for almost 5 years. And know what this engine can do.
 
Go Frank, go !!
I am VERY interested in your Kubota test.
My tractor is a Kubota, but it is the 4-cylinder variant and doesn't run wide-open.
Will you be using diesel or Jet-A for the fuel on this test? I know that diesel will be easier to acquire, but perhaps you can test both and see if there is any performance difference ?
I would like to know the final, ready-to-run weight and what PSRU that you will be using. Don't diesels have a more harsh power spike per cylinder?
Thanks for posting this alternate engine thread.
Brian

I will use best diesel I can find.
The PSRU I have 3 setup in my head i only need 1.5 or 1.6 if you know of one I'm open to ideas why I posted this here.
 
I just sold a kubota V1505 4 cyl......

You will need some way to dampen the power pulses on the redrive.
 
I just sold a kubota V1505 4 cyl......

You will need some way to dampen the power pulses on the redrive.

Would a triple belt kit take some of pulses? And at higher rpm it's a smooth running 3 cylinder. I probably will need to raise my idle.
 
Cant wait to hear about your results frank, I reckon forget the snow ski and just rig up some sort of simple belt style of redrive so you can get a prop on it to see what it can do.
Would be real interesting to see what size (and pitch) prop it could spin at about 2300 prop rpm.

wolfy
 
Just out of interest frank do you know what style of governor you have, what was engine out of?

wolfy

it's internal with dog type flaps that open injector pump has it open wider.
But I can adjust it for higher or lower RPM. if needed.

engine was out of a Exmark 72" Lazer Z XP Diesel
 
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Sounds like a great project!!

But I do worry about reliability.

I always imagined a diesel engine was tougher and more reliable than an equivalent petrol engine.
They are tougher and more reliable, but we are generally not really talking equivalent: the diesel is big, heavily built, and low revving.

As soon as you make them light and higher revving, with their higher compression and greater stresses, they become less reliable.

I have seen it with boat motors, but most recently I replaced a lot of petrol Honda powered pressure washers with equivalent horsepower Yanma diesels (and they were heavier too). Mainly done because just about everything else runs on diesel here.

The Hondas always lasted 3 years, the Yanmas have all lasted less than two years.
We are just switching back to the Hondas.
 
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Kubota is a better engine then yanmars.

i will test this engine for many hours on a test frame with a prop im sure my neighbors wont like the noise so i will probably set this up my my forest at the end of my property.
or set it up on a trailer and tow it where ever i need.

why this is a long term project still some stuff to work out.
 
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