Kubota Gas vs Kubota Diesel engine option

[DK35vince]

I have the diesel engine and have found it is very cold blooded. On mild mornings of 40F it might take 6-8 times to start it. The first few tries results in a very short run then it dies.

Sounds like you have a glow plug issue.

 

[RalphVa]

There's a BIG difference in fuel economy. A diesel engine, even a non turbo one, is 50% more fuel efficient than a carbureted gas engine. All us engineers did fuel comparisons back in the late 70s, early 80s. This is what we found. Our gas engined vehicles (all with carbs back then) used 30 mpg ton vs. 45 mpg ton for our diesels (all non turbo but the one Mitsubishi).

Today, with improvements in gas cars, they're use only 10% more fuel than a turbo diesel. The real thermodynamic difference should be 20% because of the energy in the fuel, but I think they're just putting more technology into the gas engine setups.

Ralph

Ralph

 

[ChiefBodie]

Sounds like you have a glow plug issue.

I have noticed something else that seems odd. No matter whether cold or hot, if the engine is OFF and I turn the key to ON, the glow plug indicator light comes on for about 10 seconds. Even on a HOT engine. I have not seen any other diesels I have owned do this.

 

[Industrial Toys]

My 922 is EXACTLY the same way. Even in the summer, it needs its glow plugs.

I was at the Steiner Dealer last weekend. Heard some 450s being test driven. Man, those Gas Engines sound CHEAP to my ear!

 

[johara1]

There's a BIG difference in fuel economy. A diesel engine, even a non turbo one, is 50% more fuel efficient than a carbureted gas engine. All us engineers did fuel comparisons back in the late 70s, early 80s. This is what we found. Our gas engined vehicles (all with carbs back then) used 30 mpg ton vs. 45 mpg ton for our diesels (all non turbo but the one Mitsubishi).

Today, with improvements in gas cars, they're use only 10% more fuel than a turbo diesel. The real thermodynamic difference should be 20% because of the energy in the fuel, but I think they're just putting more technology into the gas engine setups.

Ralph

Ralph

You better rethink your estimates now, with diesel 50 cents a gallon more than gas here. You better test the Diesel to a gas 4500P for economy. Factor in the higher cost of Diesel and injectors on the gas engine..... jim

 

[ChiefBodie]

I have learned an operating tip that if I see black smoke starting to emit while operating to back off the control a bit. Seems to keep things in harmony power-wise.

 

[buickanddeere]

Diesel is under 25HP because Tier IV emissions regulations are much stricter over 25 HP. In years past the diesel ruled for good reason with reliability , longtivity and excellent fuel efficiency vs a carbureted gas with points while burning leaded fuel.
Now the EPA is trying to re-write society , what we do and how we do it .
In low HP light and medium duty applications today痴 gasoline engines are a better value than today痴 Diesel engines .

 

[buickanddeere]

My :2cents:
As far as longevity, I believe diesel wins hands-down. It seems that with diesel longevity, the turbo is the weak link and one just has to be prepared to replace them at some point. (Unless it has no turbo!) Yes turbo boost power, fuel efficiency, emissions, power, etc..; but IMHO, turbos are a trade off.

As far as 32hp (gas) vs. 25hp (diesel): They probably measure that 32 hp with a wide open throttle (or close to). It's a question of do you want horsepower, or torque?
The torque the gas engine produces (and horsepower) may drop off significantly when not wide open. The torque a diesel engine can produce typically does not drop off as sharply as a gas engine at lower rpms.
Remember that horsepower= torque x rpm. "To make more power an engine needs to generate more torque, operate at higher rpm, or both." So a low torque motor at high rpms (gas) can be advertised to have more "horsepower" than a diesel motor, that although it has more torque over a wider range of rpms, it has a lesser (top end - maximum) rpm, and lesser "horsepower".
Basically: Using horsepower in a gas vs. diesel comparison is comparing apples to oranges.

HP is HP no matter is two stroke , four stroke . Gas , diesel , turbine , electric , high rpm or low rpm . The 32HP engine will perform more work per hour vs a 25HP diesel .
Lawn mowers are to be operated at full rated rpm and not lugged .
This talk of diesels lasting longer than gasses to old talk from the era of leaded gasoline and prior to common rail Diesel engines . It is 2018, not 1980.
Gas vehicles for years now have turned 300,000 miles without more than filters , spark plugs , water pumps and alternators . Emissions diesels have been in the shop for specialized $$$ service several times prior to 300,000. You can purchase an entire long block gasser for less money than just a set of diesel injectors .

 

[buickanddeere]

I believe the 25hp diesel burns 1.1 gph and the 32hp gas burns 1.5 gph.

It's hard for me to evaluate the benefit of using/needing the extra HP and torque compared to the increased difficulty of storing gas (instead of diesel) and a higher fuel burn. The higher fuel burn to make more power is understood-- there is no free lunch of course!

I probably have an equal mix of slopes (that could benefit from horsepower) and flat areas under the canopy of trees, etc, which would not need the extra power.

When are you going to break even with fuel costs ?

 

[buickanddeere]

I have the diesel engine and have found it is very cold blooded. On mild mornings of 40F it might take 6-8 times to start it. The first few tries results in a very short run then it dies.

Turn on the glow plugs to keep it from stalling .