Part 4: L2501 Turbo vs. PTO Dyno (The Results and Conclusion)
I’m sure for many readers, the following information is precisely what you’ve been waiting for. The results, period. No estimates. No blather. No guessing. No subjective observations. No excuses. You have been waiting for a culmination of factual, verifiable, objective and real measured results. Results obtained from proven testing equipment operated by professionals with years of experience. Plain and simple. Well, I’m back to deliver those results. Are you ready?
Here we go!
I had been searching for a facility to test my tractor’s performance for quite sometime. I was utterly bewildered upon discovering that very few tractor service facilities in my area have a PTO dynamometer. A PTO dynamometer measures a tractor’s performance by applying a calibrated and controlled braking force on the tractor PTO (Power Take Off) while measuring the speed of the rotation. Measuring the speed and power under a specific load allows the amount of torque produced by the engine at different speeds to be calculated. It’s a fairly complex piece of equipment. Shockingly, even my local Kubota dealer did not have a PTO dynamometer available. Not even for diagnostic purposes? Crazy. Originally I thought, since I live in what could be considered ‘tractor country’ with tons of agricultural businesses in my surrounding area that this type of equipment would be commonplace. Nope! That wasn’t the case at all.
I had to contact countless tractor service facilities outside of my local area for a PTO dynamometer, unfortunately, I wasn’t having any luck. Heck, at one point, I even contacted a PTO dynamometer manufacturer and inquired about the cost to buy my own PTO dynamometer. But, after learning that they cost upwards of $30,000, that idea was quickly squashed. Refusing to give up I continued to contact and collect clues from potential service facilities about a PTO dynamometer to test my tractor until I finally heard the words I needed to hear….”Yes, we have a PTO dyno. Yes, it is available for customer testing”. Woohoo!
The super friendly and helpful folks at Jennings Equipment, Inc. in Chehalis Washington, a Kubota dealership, were the ones that finally answered my call and were able to fulfill my request. They in fact had the elusive PTO dynamometer that I needed to evaluate my tractor’s revolutionary performance modifications and put them to the test.
Not only did they have a PTO dyno, but they have an AW AG.2X series Dynamometer featuring the latest high tech 2100SXT DynoPro computer system. This particular PTO dynamometer is arguably the best and most accurate PTO dyno in the industry today. Bonus!
Hold on a second! Before I disclose the final results, perhaps I should share my original performance goal with this Turbo system. Simply stated, my goal was to surpass the performance output of the L3901 / L3902. These tractors produce 37.5 HP and 30.6 PTO HP respectively.
You said no blather? Common man! Let’s get on with it! How’d it do?
The tractor was hooked up to the AW AG.2X dynamometer and ran for a short time to make sure everything was securely attached to the tractor, functioning properly and recording the essential data.
After the initial setup, we warmed up the tractor to operating temperature and ran it for two merciless hours of testing. The percentage of load was increased incrementally as we continued to monitor engine diagnostics, boost pressure, EGT temperatures and the subsequent performance data. The tractor was ran under full boost and a heavy load for a solid hour. There were no surprises. The engine coolant temperature remained cool and consistent throughout the testing and Turbo system performed beautifully with zero issues whatsoever.
Once again, the Turbo setup;
L2501 HST 4WD (LA525 Loader w/ 66” QA Bucket, Liquid Tire Ballast) - MHI TD025 TURBO SYSTEM - 9 PSI - Fuel Setting, 2 1/4 Full Turns (42* ambient temperature).
Folks, meet the Kubota Standard L series L2501 Turbo or, perhaps more accurately described as the Standard L series L4401 Tractor powered by a Turbocharged D1703-M-DI-E4B engine!
The AW AG.2X dynamometer recorded:
PTO = 35 PTO HP
PTO Torque = 339 LB-FT
Engine Horsepower = 44.1 HP
Engine Torque = 109.8 LB-FT
Peak EGT = 1,185*
That’s right! 35 PTO HP!!!
The Turbo kit produced a 45% increase in power! We’ve gone from a measly 19 PTO HP to a gargantuan 35 PTO HP! Yep, that’s Huge!
We achieved the 35 PTO HP at the factory 2,105 RPM PTO setting, our target RPM. Absolutely fantastic! We recorded a maximum of 1,185* EGT, a safe temperature for sustained usage. Excellent! We recorded a maximum boost pressure of 9PSI under full load. Perfect!
In addition, at just a 10% load, the tractor is producing a whopping 26 PTO HP at 2,105 RPM’s. That’s worth repeating. At just a 10% load, the tractor is producing 26 PTO HP. What does that mean? The Turbo system is making so much power and torque that the tractor doesn’t even have to work hard to run most PTO implements. Simply remarkable!
The knowledgeable Jennings staff and technicians had a couple suggestions regarding the tractor and Turbo system. They said to make sure to use the clutch and engage the PTO at idle. I’m pretty sure that’s standard procedure but, they wanted to be clear since any deviation from this routine could cause excessive wear on these components due to the colossal power improvement. No surprise there.
To put the gains into perspective, here are the power outputs of a standard L2501, an L2501 with the ‘FREE’ Injection Pump Timing Modification, an L3901 / L3902 and the L2501 Turbo (all equipped with HST);
L2501 Stock = 24.8 HP / 70.2 LB-FT
19 PTO HP at 2,105 RPM
L2501 w/ ‘FREE’ Injection Pump Timing = 31.2 HP / 77.3 LB-FT
25 PTO HP at 2,200 RPM
L3901 / L3902 = 37.5 HP / 83.6 LB-FT
30.6 PTO HP at 2,700 RPM
L2501 Turbo = 44.1 HP / 109.8 LB-FT
35 PTO HP at 2,105 RPM
I’m sure you can draw your own conclusions. I know I have.
On a side note, unbeknownst to me, apparently there was some sort of side betting going on by the Jennings staff regarding the numbers my tractor was going to make. And, had I known about the bets, the tractor would have made some serious money! Based on their prior experiences testing other tractors, nobody there thought this tractor would produce anything north of 30 PTO HP. Heck, I honestly didn’t know either! But, that’s why the testing had to be done!
Altogether we’re obviously very happy with the results. This Turbo system surpassed my goals and performed exceptionally well during the testing. Everyone involved in the testing process was extremely impressed with the Turbo system, the components, the quality, the packaging, the performance and the final outcome.
That’s great Bro! Congratulations….But, you’re probably rolling coal and murdering the earth! Sorry to rain on your parade dude!
Nope! We’re running super clean! During the testing there wasn’t any visible smoke at any RPM, or at any load. The tractor is burning clean and efficiently in all operating conditions. The only visible smoke I have experienced with this Turbo setup is during startup, which is the same behavior with stock fuel settings. Albeit, there is a bit more smoke with the modified settings when compared to the original fuel setting. But, that’s only common sense and should be expected.
Okay. Fine! You got my attention. I want a L2501 Turbo kit. But, what if I’m not as awe inspired with the results as you are? I want this Turbo kit to produce even more power!!!
Fair enough. Fair question. Yes, we could have made more PTO HP. We left plenty of additional power on the table (or dyno). We could have easily pushed the power output well beyond 35 PTO HP. How? We could have continued to increase the load on the tractor and as the RPM’s naturally drop with the additional load, we could have then increased the throttle and RPM’s or even surpass the rated PTO RPM’s we were testing at. The increase in throttle input and RPM’s would have made more power. We weren’t anywhere close to stalling the tractor. Moreover, considering how clean the engine is running, we could have easily added more fuel, thereby producing even more power. I estimate this Turbo system can easily produce 40 PTO HP on the L2501, if one so desired. Anyone wanna bet?