Kubota L2501 Turbo: A Journey Defined - The Tractor, The Comparison, The Modification, The Results

[ericm979]

If it's the same engine as the L3901 just detuned, and it makes about the same HP, isn't it seeing about the same combustion chamber pressures? Maybe differences in injection timing would affect peak pressure.

I didn't compare parts lists so I'm assuming that it's the same block, head and pistons. It might be interesting to compare part numbers.

 

[dh206]

great write up. I wonder two things:
1) where did you end up integrating your EGT reading? Did you put a gauge on the dash somewhere?
2) With the fuel adjustment, what's your average runtime on a tank vs before? (increase in consumption)

 

[Rdrcr]

EXACTLY, and every OEM turbocharged, boosted car sold today has this insert installed for the top ring land.

You'll notice 3 basic differences on Kubota NA vs. boosted pre tier 4 engines.

1) intake manifold, NA has a runner type or non plenum manifold, the boosted always have a "log" type manifold or one with a plenum, simply a large area that evenly distributes the pressure to each runner. So where a naturally aspirated engine has a vacuum at each intake valve a boosted engine has pressure at each intake valve, at load that is. I learned this from a Dodge Cummins truck pull champion, he showed me how the Cummins manifold needs a plenum because the rear cylinders get much more charge without it and they are usually the first ones to fail.

2) Oil cooler, there are no piston oil squirters on the pre-emission Kubota engines, not sure about the newest ones, please correct me if I am wrong.

3) Pistons with that hard insert on the top ring, to help with the major increase in combustion pressure.
As far as I could tell that is about it, they usually run the same timing spec and fuel injector although the rack setting is much higher with the boosted engine as you found out.

No I don't have a pyrometer, I've quickly opened the hood after a very hard pull and the boost tube is cold as ice. I would have melted a piston if it had the exhaust gotten too hot.

I didn't want to re-invent the wheel, just needed more power because 39hp on a 5500 pound machine is not nearly enough.
To the guy with the new Kioti CK2610 machine, I have one and absolutely love it, a simple fuel rack adjustment will get you much more power, forget the turbo install, leave it alone and enjoy your excellent choice of machine. 425 trouble free hours now, I chose the gear version for simplicity.

Deezler...thanks!

You have to monitor EGT’s on a Turbocharged N/A application like yours (and with the L2501).

It is complete speculation regarding the reasons why your engine failed at 400 hours. It could be pistons. Or, it could be 1,600 degree combustion temperatures sustained over a long period of time. Who knows…If you’re not monitoring engine diagnostics and you have no idea on combustion temperatures it’s no surprise it eventually failed and I’m rather surprised it lasted 400 hours.

The D1703 is a very capable engine that can be boosted safely assuming the user monitors engine diagnostics and maintains a safe EGT and combustion temperatures.

Mike

 

[Rdrcr]

great write up. I wonder two things:
1) where did you end up integrating your EGT reading? Did you put a gauge on the dash somewhere?
2) With the fuel adjustment, what's your average runtime on a tank vs before? (increase in consumption)

Thank you!

EGT’s are being recorded before the Turbocharger in the Turbo adapter. It’s the best compromise and gives us a measurement based on all 3 cylinders. Right now, I’m using a diagnostic gauge that I have mounted on my loader bracket. I’ll eventually transition to a fixed gauge on the dashboard.

I haven’t yet measured the fuel consumption. The consumption has gone up a bit, but, the Tractor remains incredibly fuel efficient.

Mike

 

[Rdrcr]

Very well done on your entire journey. Nice to know about the dyno on the west side. My neighbor bought this same tractor from me and would like a bit more power for our steep canyon. I would end up being the installer if he decides to go with the turbo mod. Thanks for sharing your time and knowledge. GO GEARHEADS!

Thank you!

It’s been quite a journey but, we’re definitely happy with the results. This is definitely a “gearheads” solution for L2501 tractor owners!

Mike

 

[LowellBen]

My property is at 8200' in Colorado. I sure would like my Mahindra 1538 to be able to make sea level horsepower! But it has all that emissions crap on the engine so I'm probably stuck with having to deal with the power loss.

 

[mslisaj]

Amazing thread!! Beautiful install too. My 25hp tractor is almost out of warranty so I'm looking for improvements too. But thank you for such a well written article. Really enjoyed it and I hope you get many years of trouble free service from this tractor. Nice Job!!

 

[Rdrcr]

My property is at 8200' in Colorado. I sure would like my Mahindra 1538 to be able to make sea level horsepower! But it has all that emissions crap on the engine so I'm probably stuck with having to deal with the power loss.

The issue with modifying the emissions equipped tractors are the electronics (ECU). Here in the states we don’t have any reliable sources to program the ECU after modifications have been made.

There are a couple “tuners” in Europe that focus their programming mainly on removing the emissions equipment from the DPF and DEF tractors but, not necessarily for horsepower upgrades.

Mike

 

[LowellBen]

Hey Mike,

You did a super job on the 2501. I would like to do the turbo-normalize thing just to get the engine back to sea level rated power while operating at our 8200'. I haven't looked at any detail in how the Bosch ECU handles air mass flow going into the engine. The engine is Final Tier 4 compliant and doesn't use DEF or DPF. It has something called DOC (diesel oxidation catalyst). I would think that the ECU wouldn't need reprogramming since the turbo would just be pushing enough air into the engine to think it was back at sea level. But there is probably no way of integrating a turbo into the exhaust path.

 

[Rdrcr]

Hey Mike,

You did a super job on the 2501. I would like to do the turbo-normalize thing just to get the engine back to sea level rated power while operating at our 8200'. I haven't looked at any detail in how the Bosch ECU handles air mass flow going into the engine. The engine is Final Tier 4 compliant and doesn't use DEF or DPF. It has something called DOC (diesel oxidation catalyst). I would think that the ECU wouldn't need reprogramming since the turbo would just be pushing enough air into the engine to think it was back at sea level. But there is probably no way of integrating a turbo into the exhaust path.

The key factor in modifying your tractor is figuring out how the BOSCH ECU handles the air mass. Will it add more fuel on its own? Or, would it need to be programmed?

There were some gasoline powered vehicles in the 90’s era that had ECU’s that would automatically add additional fuel when more air was present/detected. But, there were limits. Basically, the ECU’s were able to handle 3-4PSI but would begin running lean beyond that (the fuel injector size was also a limiting factor).

It would be very interesting to learn how the BOSCH ECU would handle forced induction.

Mike