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

[Rdrcr]

Part 1: Background

The purpose of this thread is to share the concept, creation, progress and performance of my custom Turbocharged Kubota L2501 HST 4WD tractor.

I’ll start by offering my opinions on this tractor, why I bought it, how it’s performed, the advantages and disadvantages, and why I chose to modify it in such spectacular fashion.

This thread is not intended to compare alternative tractors (smaller, larger, heavier models, different brands, etc.). That said, I will be making some statistical comparisons between Kubota’s Standard L Series tractors, since, they are all, basically the same tractor with varying cost and performance aspects.

Let’s begin.

My Kubota L2501 HST 4WD is my second tractor (third, if you include the garden-tractor variety).

I’m operating my tractor on 5 acres of undeveloped heavily wooded forest land. The property itself is roughly 500ft above sea level and the terrain consists of flat areas along with moderate and steep hills to the north and northeast.

My goal with the property is to transform the wild untamed forest and create a park-like atmosphere and appearance without disturbing too much of the natural beauty.

My tractor is used to grade and level land, till dirt, move dirt, move brush, skid logs, transport trees and logs, make trails through the forest, maintain our gravel driveway, remove stumps, run a PTO powered wood chipper, run a 15KW PTO backup generator and to load and unload miscellaneous materials and products from delivery trucks.
Thankfully, I have a ZTR mower (zero-turn riding lawnmower) to maintain the grass, weeds and light brush.

When I first began shopping for a tractor I focused my attention on the sub-compact variety. I wanted a small, all-in-one machine, that could fit anywhere, feel comfortable, do tractor things, but also, mow the lawn.

Mowing the lawn was a very important consideration at this particular time in my property ownership career. I was fixated on acquiring a versatile tractor capable of mowing the grass since I had grown tired of having to stop in the middle of my mowing chores to fill the gas tank on my garden tractor. A truly loathsome inconvenience! I wanted to make certain that whatever tractor I purchased would have enough fuel capacity to mow my entire property on one tank of fuel and I knew a small diesel powered tractor wouldn’t have any issue accomplishing this task. That said, I was also beginning to realize the need for a real tractor to help with property management, improvements and maintenance tasks. At this early stage in my understanding, I didn’t have a bona fide vision, or grasp of a tractors true capabilities.

Friends, neighbors and co-workers familiar with my property quickly lured me away from purchasing a small sub-compact tractor and suggested I go bigger, much bigger. Most folks were urging me to buy a medium to large compact or, even a small utility tractor. But, doing so, meant having to purchase two separate machines. One for tractor work and one for mowing duties. The thought of purchasing two machines seemed completely unnecessary and incredibly expensive. Further complicating my decision making ability was due to my ignorance and inexperience. At the time, I didn’t fully understand the limitations of a tractor’s size and weight. Consequently, I was unable to fully comprehend the reasoning behind each of the tractor recommendations that were being offered to me. Purchasing a small tractor, with a mid-mounted mower, seemed to make a lot more sense. Respectfully, however, I couldn’t entirely disregard their suggestions since I knew they were all based on decades of operating experience from very knowledgeable individuals that really wanted to help me buy the ideal tractor for my property.

After cross-shopping many brands, tractors and tractor sizes, I eventually made a decision. A decision that pretty much disregarded all the advice and suggestions I received. A decision purely based on my own enormously extensive inexperience. My decision was to purchase a brand new Kubota B2601 HST 4WD tractor equipped with a front end loader and of course, most importantly, a 60” MMM (mid-mount mower). In the end, I just didn’t think a larger tractor was necessary. I’m just mowing the lawn for heavens sake!

I was tremendously proud of my decision because I technically bought a larger tractor than I was originally planning to purchase. I bought a compact tractor, not a sub-compact tractor! In my mind, this slight increase in tractor size was surely enough to appease the generous souls that offered me their advice and wisdom. See I listened! Hooray for me!
Though, in reality, I didn’t listen. The B2601 was nowhere near as big, or as heavy as the tractor I was originally encouraged to purchase.

As disappointed as some individuals were regarding my decision, they were still happy I purchased a tractor. Because any tractor, is better than no tractor! And honestly, purchasing the B2601 wasn’t a horrible decision after all. It was a great tractor and served me well, but it just wasn’t the ‘right’ tractor for my property and uses. The B2601 simply lacked the lift capacity, the size and the weight required for removing medium to large stumps, carrying logs, carrying stumps and the heavy ground engagement work that was still needed on my property.

I’m sure most of us can agree, first hand experience is paramount. Nothing teaches you more than learning from your own mistakes. It can be painful but, I welcome it. That said, I always hope my mistakes aren’t too costly fiscally or physically. Luckily, this one wasn’t and within a year, I was once again visiting local tractor dealerships prepared to purchase a larger tractor (and a dedicated lawn mower).

When you are in the market for a new tractor, it’s worth repeating some very wise tractor shopping lore;
Tractors in general, appear gigantic at the dealership parked side by side one another, and then, when you get them home, they mysteriously shrink! Have you noticed this? It’s hilarious, but true!

After many agonizing (enjoyable) weeks of research, visiting dealerships and cross-shopping multiple brands and tractors such as the John Deere 3025E, Massy Ferguson 1825E (and 1835M), Kioti CK2610H, LS MT225HE, Branson 2515H and several others, I was drawn to and eventually purchased the Kubota Standard L Series L2501 ‘Economy’ tractor.

I purchased the Kubota L2501 for several reasons. First and foremost, bang-for-your-buck. You get a lot of pure tractor for the money. The L2501 is a substantial, raw and robustly designed machine made for arduous tractor work. The combination of its size, weight, lift capacity, and maneuverability are near perfect for my property. The L2501 has an impressive track record for trouble free operation, exceptional build quality and amazing reliability. In addition, the L2501’s three cylinder diesel engine delivers exceptional fuel economy and also produces an impressive amount of torque for its size, especially considering it is a naturally aspirated. Having owned several overly complicated and expensive modern diesel powered cars, trucks and SUV’s, I appreciate simplicity. The L2501’s engine is thankfully, a simple mechanical diesel and is not equipped with modern diesel emissions equipment, or electronics. Meaning it does not have an ECM (engine control module) or DPF (diesel particulate filter) and doesn’t require emission Regens (a process that converts soot to ash within the exhaust system) which create excessive heat, wastes fuel and mandates high RPM engine operation. A huge bonus for sure! Furthermore, another benefit is the L2501’s popularity. It’s one of the best selling tractors in the USA and has very good resale value (an important consideration when you’re not fully confident in your purchasing decisions, like me).

All of these characteristics seemed extremely well suited for my property and my intended uses. Plus, I was already familiar with the Kubota brand, I have a phenomenal dealer less than 40 miles away and the L2501 was the tractor that many folks, including my Kubota dealer, originally recommended.
Whew! That’s a TON of good stuff! Sold!

The L2501 is an awesome tractor but, is it the perfect tractor? Not quite. So why isn’t the L2501 a perfect tractor?
Several things, let me explain.

Naturally, I’ve spent quite a bit of time reading, researching and operating the Kubota L2501 tractor. During this process I’ve catalogued many of the complaints expressed from owners, previous owners, shoppers, hater’s and those in between.

Here’s a synopsis of those opinions I’ve compiled over time.

The L2501 is a budget minded economy tractor that lacks creature comforts and doesn’t offer exceptional ergonomics and controls, especially when compared to its rivals. Absolutely correct! But, the L2501’s hydraulic operation is twice as smooth as the competitors and seriously, this is a budget tractor. These limitations are pretty much expected from a tractor in this category, Right?

Cost. The Kubota L2501 is expensive when compared to other 25HP economy tractors. It ain’t worth the money dummy! There’s some truth to this. In most cases, the L2501 will cost more than an alternative brand economy tractor. Admittedly, you’re buying the brand, Kubota. But, you’re also buying a strong dealer network. You’re buying quality, exceptional engineering, design, reliability, long term parts availability and high resale value.
Hmmm, come to think about it, there might be some additional value there. You make the call.

The L2501’s most obvious disadvantage and unquestionably the most meaningful, is the low engine horsepower and measly PTO power output which affects the tractor’s ability to get work done.

What is the PTO? The PTO (power take off) is the tractors stub shaft that transfers power to a PTO driven implement, or machine. Power transfer is accomplished by connecting a drive shaft from the implement to the tractors PTO stub shaft. Got it? Great.

The low PTO power drastically limits the size, type and availability of rear PTO powered implements you can effectively run with the L2501.

The low engine power effects operating speed and slows the tractor down while powering and running rear PTO implements, like a flail mower, tiller, snowblower or large rotary cutter. This issue can be compounded depending on conditions such as tall grass and/or steep terrain. Conditions like these may require using Low gear, slowing down the operating speed and/or potentially stalling the tractor.

The same can be said for larger heavier dirt working ground-engagement implements too, like box blades and land planes. The L2501 can lift and carry them without issue but, the larger implements, full of material can create too much drag and the tractor simply doesn’t have enough power to pull these type of implements at optimal speeds. Once again, conditions such as these would very likely require using Low gear, slowing down the operating speed and/or potentially stalling the tractor. Steep hills, or challenging terrain can make these tasks impossible.

Even though the L2501 has three forward gears, in reality, it only has two fully usable gears, Low and Medium gear. The High gear? Not so much. The L2501 gear situation has been explained to me as; (L) for loader work, (M) for mowing and (H) for highway. While this interpretation makes perfect sense, the (H) gear is virtually useless on this tractor. Basically, the (H) gear can only be used for transportation purposes, on completely flat terrain. Hills? Forget about it.

And, the L2501’s engine, being naturally aspirated and having only 24.8 HP can cause performance to suffer in high altitude operation (luckily, something I don’t have to worry about).

While the L2501 might not be perfect, it has performed near flawlessly on my property and has done everything I’ve asked of it. Perhaps, my annoyance with this tractor is because I want work to get done faster and I believe it is possible to improve the L2501’s overall performance. Am I impatient? Yep! The question is; can I make the L2501 the perfect tractor?

In order to do that, I must explain the key challenges I experience on my property with this tractor.

For example, I transport all of my brush, trees, logs, stumps and basically anything I need to burn up and over a long steep hill. This hill is a 22* slope, 40% grade. It’s fairly steep and 4WD is required in almost anything that goes up, or down the hill. My L2501 can make it up the hill, carrying a load in both (L) and (M) gears at a minimum of 2,200 RPM. In (L) gear, going up the hill is excruciating slow and frustrating. In (M) gear, the tractor struggles and bogs down several hundred RPM’s as it climbs the hill, slowing to a crawl and requires feathering of the HST pedal to maintain progress. (M) gear is certainly better than (L) gear but, (M) gear is still really slow and it’s difficult to maintain a consistent speed. In (H) gear? Uhhh, no. The tractor bogs down and stalls, regardless of engine RPM. I don’t necessarily need the tractor to get up the hill faster but, I’d like to have more power to maintain speed while going up this hill, in (M) gear. In the tractor’s present state, I think it would be impossible, for example , to power a large rotary cutter, or even pull a box blade going up this hill, in anything but (L) gear.

Also, the L2501 doesn’t seem to have enough power to pull a heavy commercial box blade full of material in (M) gear. I would like to have more power to use the larger, heavier ground engaging dirt working implements in challenging conditions at my desired operating speeds.

Speaking of operating speeds. I’d like to be able to have full use of (H) gear and maintain ground speed regardless of the terrain conditions. Hills and flat terrain. Remember? I’m impatient!
Right now, I can’t fully utilize (H) gear, even for transportation purposes and that needs to change.

I’d also appreciate having more power for my PTO powered wood chipper and have enough power to run a 15KW PTO backup generator.

Okay. I know what you’re thinking, Mike you moron! Kubota already has a solution to the shortcomings of your weak, overrated, underperforming and worthless L2501 tractor. Your prayers are answered!!! The L3901 HST 4WD!!! Heck, you fool! You may be able to save a little money and get away with a L3301 HST 4WD!!! Now, sell your embarrassing L2501 immediately and get a real tractor!!! One with power to spare!!! You’re welcome….You jackass!!!

Perhaps you’re right. But, not so fast. I bought the L2501 for it’s simplicity. It’s reliability. It’s value. I bought the L2501 because I don’t want to deal with computers, emissions, Regens, DPF, or high rpm operation. These are things that become a nuisance, a hinderance, a concern with ownership over time. I don’t want the added complexity, complications, or the additional cost.

Hmmm, what are my options then?
Let’s take a look.

Mike

 

[Rdrcr]

Part 2: Evaluating the options.

It’s true. I could simply sell my L2501 and buy a new, more-powerful Kubota Standard L Series tractor. The L3301, the L3901, the L3302 and the L3902 all have more power and upgrading to a new tractor seems like it really would make sense. But, does it really make sense? Would purchasing one of these tractors be cost effective? Would purchasing a new tractor be the best option?

To determine that, I’ll need to examine the cost differences and performance advantages of each of the Kubota Standard L Series tractors (sorry, I’m excluding the L4701 due to it’s larger frame, size and weight).

The following information is based on 2022 Kubota Standard L Series tractors specifications and pricing listed on Kubota’s official website at the time of this writing. I have equipped each tractor with an HST transmission and 4WD for the comparison. I’ll be using the L2501 pricing and power figures as the baseline for the comparison. In addition, I’ll provide a PTO HP per dollar figure, for fun! Why not?

The Kubota L2501 produces 24.8 HP and delivers 19 PTO HP ($963 per PTO HP).

The Kubota L3301 produces 33 HP and delivers 26.2 PTO HP ($799 per PTO HP). This tractor makes 25% more power and is $2,617 more expensive than the L2501.

The Kubota L3302 produces 33 HP and delivers 26.1 PTO HP ($912 per PTO HP). This tractor makes 25% more power and is $4,745 more expensive than the L2501. Ouch! That stings!
However, it’s certainly worth mentioning, the L3302 is a very nice tractor and I for one, really appreciate the new 02 model’s innovative features, comfort and cosmetic upgrades. Okay! Back to comparisons!

The Kubota L3901 produces 37.5 HP and delivers 30.6 PTO HP ($754 per PTO HP). This tractor makes 34% more power and is $4,734 more expensive than the L2501.

And finally, the Kubota L3902 produces 37.5 HP and delivers 30.3 PTO HP ($860 per PTO HP). This tractor makes 34% more power and is $6,987 more expensive than the L2501. Wow. Brutal! However, like the L3302, the L3902, is one heck of a nice tractor with features and upgrades to match.

So, where do these revelations leave us? Well, the L3901 delivers the class leading $754 per PTO HP and I obviously have plenty of tractor options to consider. That’s for sure. But, am I considering ALL the options? Is there something I’m missing?

I’m pretty sure I have a different mentality than most tractor and large property owners. I grew up in the city and had a father who had a passion for Hot Rods and Muscle Cars. That passion was passed on to me at an early age and I spent a lot of time early in life modifying and racing cars. Because of my experiences, I look at mechanical objects a little different. The first question I ask myself is; can I make what I currently own better? Can it be modified in any way to make it perform better, or be more competitive? Can I apply the same automotive performance principles, to a tractor? Can the Kubota L2501 be modified to produce more power?

Well, yes. As a matter of fact, you can. And, surprisingly I didn’t even have to experiment on my own, to figure it out. Several tractor enthusiasts and forum members have been enhancing their tractor’s performance in a variety of ways and I’ve been studying these projects and their progress for as long as they have been sharing them.

It’s been established that the L2501’s engine , the D1703-M-DI-E4B, is detuned from the factory to meet Tier 4 emission standards. This same engine, in other applications makes a lot more power. Kubota detunes the L2501’s D1703 engine by limiting the engine RPM’s, retarding the injection pump timing and restricting its fuel consumption.

We know how the L2501 compares against the other more powerful Kubota Standard L Series tractors based on the brilliant cost vs. performance analysis expertly presented earlier in this thread. We also know some L2501 pioneers have modified their tractors and made substantial gains in power and performance for not much money. In some cases, no money. Their modifications simply cost time, nerve and competence.

Ultimately, my decision to purchase a new tractor, or modify my L2501 will be established on a cost vs. performance basis. Pretty simple. If it’s cheaper for me sell my tractor and buy a new more powerful Kubota Standard L Series tractor, than that’s the direction I’ll go. If it’s less expensive and more favorable to modify my L2501, then that’s the direction I’ll go. So, what do these mysterious modifications and performance gains look like?

Let’s break it down.

The following performance data is based on actual independent PTO dyno results. I am simply using this information obtained from several sources as a foundation to estimate the additional power these modifications can potentially produce. Since each of these modifications require a fueling adjustment determined by the individual performing modification to increase power, your mileage may vary.

We know from the results of a recent PTO dyno session that an L2501 produced 31 HP and delivered 25 PTO HP modified with an injection pump timing advancement and a fuel adjustment. That’s a 20% increase in power! And $733 per PTO HP! Essentially, this modification produces the same power and performance as a L3301 / L3302, for FREE!!!
This of course, is assuming you poses the mechanical skill and technical understanding to perform this modification. But, did I mention it’s FREE?

By performing this modification on the L2501, you’re saving $2,617 over the L3301 and $4,745 over the L3302 and you’re rewarded with virtually the same performance. You can’t beat that! Period.

Hmmm, what if I want, or need, more PTO power? What about adding a Turbocharger? Diesel engines respond very well to Turbocharging! It took some time but, I found an example of a Turbocharged L2501 that was also ran on a PTO dyno. This particular L2501 Turbo setup is only producing 4 PSI of boost pressure. Regardless, this tractor delivered 38 HP and made 31 PTO HP. That’s 35% more power than stock. Wow! That’s impressive!

The L2501 Turbo is virtually making the same power as the L3901 / L3902 without any additional engine modifications. But, is there any cost savings? Yes indeed! Assuming a proper bolt-on L2501 Turbo kit will cost roughly $2,500, you’re saving $2,234 over the L3901 and $4,487 over the L3902.
Moreover, the L2501 Turbo delivers an amazing $674 per PTO HP which is better than all other available options and the best value, in terms of total tractor investment!

I’m thinking a Turbo upgrade is starting to emerge as a pretty darn tempting option!

Can even more power be made? Yes! There’s another example of an L2501 Turbo with additional modifications. This tractor has been further modified with an increased RPM limit, an injection pump timing advancement, a massive fuel adjustment and a larger Mitsubishi MHI TD03 turbocharger making an enormous 12 PSI of boost pressure. This particular setup hasn’t been tested on a PTO dyno. But, based on the the PTO dyno results that are available, I approximate this particular L2501 is making roughly 45-50 HP and 37-41 PTO HP! Heck, it could possibly be making even more power. Simply amazing!

Decision time.

Of course, it’s never that easy. As with anything in life, there are always compromises. Adding any of these remarkable modifications to your L2501 will void your warranty (if applicable). Everything comes with a cost. So, you will have to ask yourself, is it more important to have a productive and powerful simple-mechanical-diesel powered tractor without emissions and without a warranty? Or, is it more important to have a powerful tractor with a warranty and be forced to endure the complicated emissions system throughout the lifetime of ownership?

You decide!
I already did.

I believe the case has been made and it makes more sense to modify my L2501 instead of purchasing a new tractor. But, which modification? The ‘FREE’ injection pump timing advancement modification, or a Turbocharger kit? Both options require a fueling adjustment and it’s hard to argue with ‘FREE’. So the choice between the two modifications in my opinion, comes down to performance goals, mechanical skill, nerve and cost.

The injection pump timing modification is a fairly involved process. It requires the removal and disassembly of several key fuel and induction components to obtain access to the diesel injection pump spacer plates that ultimately need to be removed in order to advance the injection timing. I’ll be honest, it’s terrifying. However, there are some great step-by-step instructions and videos available online to help anyone perform this modification successfully. If you’re looking for 25 HP at the PTO this might be the way to go! Did I mention it’s FREE?

As tempting as the injection pump timing modification is, I prefer more straightforward and less complicated projects. Installing a bolt-on Turbocharger kit, by comparison, is easy. You’re basically just replacing the muffler and swapping some intake pipes. Like I said, easy! I’m definitely more of a parts-changer, than a professional, or even shade-tree mechanic.

I’m sure 31 HP and 25 PTO HP would be enough, but I’m looking for a little bit more headroom. Installing a Turbo Kit should deliver at least 38 HP and 31 PTO HP and I believe that’s the increase in power I’m seeking to accomplish my goals. Plus, as I mentioned earlier, Diesel engines respond really well to turbocharging.

I’m going Turbo!!!!

Mike

 

[Rdrcr]

Part 3: Turbo design, fabrication, installation and testing

My Turbo build begins on the heels of a couple very successful turbo setups already running on L2501 tractors. These particular Turbo setups encouraged me to begin the planning and research necessary to create my own Turbo system.

My goal is to design, fabricate, develop and install a turbocharger system that performs flawlessly on a completely stock L2501 tractor. My Turbo system will be designed as a straightforward bolt-on affair that can be installed with simple hand tools and basic mechanical knowledge. It’ll operate within the factory RPM range and at the optimal PTO RPM. It’ll enhance the performance of the L2501 without any further modifications.
It’ll be the ultimate L2501 attachment!

To achieve these lofty goals I’ve commissioned the help of a very good friend. He will be lending a hand and has a long list of automotive accolades and accomplishments in land-speed and custom Hot rod building. He is a former Indy car and V8 Supercar mechanic, engineer and fabricator. His assistance is needed as I simply do not poses the welding and fabrication skills required to bring this project to fruition. Having his assistance with this endeavor is a real privilege. I’m fully confident that together we will build an amazing Turbo system.

With any small displacement engine, Turbo size is crucial, but with the L2501, it’s even more critical. Why? Because the L2501’s engine (D1703-M-DI-E4B) operates at such low RPM (2,400 maximum, 2,105 PTO). After speaking with several industry experts familiar with the L2501’s engine and it’s operating capacity, the collective minds decided on a brand new Industrial/Agricultural Mitsubishi MHI TD025 Turbocharger, as the best option. It’s literally, the smallest Turbo I’ve ever seen.

This tiny Turbo is somewhat undersized for the D1703’s 1.647L displacement and was originally designed for use on Kubota’s D1503 1.5L engine. This Turbo was chosen, however, because it’ll perform perfectly amidst the L2501 engine’s low RPM operating environment. And don’t worry, this miniature Turbo can support up to 90 HP. Yeah. I think we’re good! With the Turbo decision behind us, I began looking at other components.

As with any project, quality materials are essential to success so I decided on using only high quality 316 and 304L stainless steel for all plate, tubing, clamps and adapters to ensure longevity and match the quality, reputation and reliability of the Kubota Standard L Series tractor and the brilliant little Mitsubishi MHI TD025 Turbocharger. Quite frankly, it wouldn’t make any sense to do otherwise.

In the very early stages of my research I read that the factory L2501 intake and air cleaner assembly is highly restrictive. Upon learning this news, I figured it was time to experiment. I replaced the factory intake hose and air filter housing and fabricated a new high flow aluminum short-ram intake and finished it off with a high performance aftermarket off-road air filter designed to handle the extreme dusty conditions encountered in Baja and Rally racing.

As I’ve mentioned previously, my big hill is my L2501’s nemesis. The tractor doesn’t appreciate the challenge of traversing this obstacle and always struggles to make it to the top carrying a load. The custom intake noticeably improved the tractors ability to climb the hill in (M) gear. The newfound ability wasn’t anything earth shattering, the tractor still struggled, but the RPM’s would only drop a few hundred RPM’s, instead of several hundred RPM’s.

There were some drawbacks, however. The engine and intake noise was noticeably louder with the custom intake. I never thought to measure the increased racket but, I can tell you it was a little uncomfortable operating the tractor without wearing ear protection. And with further testing, I found there were some issues with air filtration. After many hours of hard use in dusty conditions, I found evidence of very fine dirt film in the intake tube. It’s probably nothing to be alarmed by but, I never saw any sign of dirt particles, or film inside the stock intake system. So, I removed the short-Ram intake and reinstalled the OEM intake assembly and air cleaner for piece of mind.

Due to the questionable air filtration properties found with the aftermarket high performance air filter and the general assumption that a tractor will be used in dusty conditions, I knew I wanted my Turbo system to utilize the OEM intake assembly and air filter, even if it costs some performance (I’ll get to that later). Naturally, it’s much better to have superior air filtration protection than the alternative.

Roaring ahead with my thoughtful planning and ideas, I began to list additional design requirements and features we would be providing with this Bolt-on Turbo Kit.

I want my Turbo system to maintain a stock unmodified appearance. Meaning, I want to make sure all factory body panels remain in place and the Turbocharger system itself, including all piping and tubing components, fit snugly under the hood, no cutting, modifying, or debauchery required. Continuing with the “stock appearance” theme I recognized the importance of keeping the exhaust pipe in the factory location. By doing so, it will help keep the exhaust fumes away from the operator while running the tractor. I’m sure we all agree, this is a keen resolution and we’ll make it happen!

Next, we turned to mounting the Turbo on the L2501’s factory exhaust manifold. I know, I know, this topic sounds incredibly boring and ridiculously unnecessary but, it is truly an important consideration. The Mitsubishi MHI TD025 Turbocharger will not simply bolt on the L2501’s exhaust manifold. Of course, this discovery is unbelievably disappointing news! To resolve this issue, we had to decide to either fabricate a custom Turbo exhaust manifold, or make some type of an adapter to mount the Turbo to the factory exhaust manifold. A gloriously awe inspiring extravagant custom stainless steel tubular Turbo exhaust manifold would be wildly awesome and incredibly impressive, but with material costs, time and labor, it would also double the cost of the Turbo system.
So, an adapter it is! Heavy sigh.

Most guys in this situation will simply make a “sandwich” adapter to mount the Turbo to the exhaust manifold. It involves taking a piece of steel plate, drilling some holes, bolting it to the exhaust manifold and installing the Turbocharger on top. It’s cheap and effective. However, that’s not what we’re doing, we’re fabricating a proper adapter! Why?

A couple reasons. First, a mandatory requirement for my Turbo system is providing a provision for an EGT (exhaust gas temperature) probe, also called, a pyrometer. The pryometer will be used to monitor engine performance, engine health and fueling adjustments required for tuning purposes. The best location for the EGT probe is in the exhaust collector before the Turbocharger. This way, the probe can measure the temperature of all three cylinders together (not just a single cylinder) before the gases reach the Turbo. Had we decided to pursue the cheapest possible solution, an adapter plate, we wouldn’t be able to provide a provision for an EGT probe. That ain’t gonna happen!

Secondly, there are some performance benefits with a properly designed and engineered Turbo adapter. So, assuming we’re successful in this endeavor, this hard work will payoff. For one, the Turbo inlet diameter and the exhaust manifold outlet diameter are not the same size. By installing a properly engineered Turbo adapter, we’re able to transition the tubing diameter gradually maximizing exhaust flow, improving velocity, which results in faster Turbo response and spool characteristics, ultimately improving performance. Excellent!
I realize this sounds easy but, it takes a lot of additional design, engineering and fabrication work to make a proper Turbo adapter. Fun! Well, not really.

All of these foolish Turbo adapter ideas greatly affect the location and position of the turbocharger in relation to the engine, engine components, exhaust manifold, firewall, hood and hood side panels. We have to make certain that not just the turbo, but all the other turbo components will have enough clearance and will fit under the hood without issue, or interference allowing everything to work in harmony. Wonderful! Not surprising, it took more time than planned but, we eventually got the adapter fabricated, installed and the Turbo properly positioned under the hood.

The next big challenge was the Turbo down pipe and exhaust. All things considered, pushing the Turbo forward just a couple inches would make things so much easier. But, since we’re cheap bastards and I decided against building a fabulous custom stainless steel tubular Turbo exhaust manifold, moving the Turbo forward, is not possible. So it took a colossal amount time and effort to fabricate the down pipe and shape it in such a way to maximize performance, fit the tight confines under the hood with acceptable clearance and allow access to the mounting hardware. But, we did it! Thank heavens!
We’re very happy with the results.

How about the Installation? What is involved? How long does it take? Can anyone do it?

It’s one thing to design, fabricate and build an entire Bolt-on Turbo system. But, it’s a whole new challenge for someone completely unfamiliar with the project to install it. Thankfully we had that in mind. We wanted to make sure the Turbo kit is easy to install (and remove if necessary).

The installation itself consists of several steps starting with the removal of the front loader, the hood and plastic hood side panels. It’s a good idea to have a buddy help with the unruly hood.

Once those obstacles are removed, you just need to remove the muffler, factory rubber intake hose pipe and CCV (crank case ventilation) hose. With those items in the garbage (stored in a safe place), it’s time to bolt on the Turbo adapter, followed with Turbocharger and the down-pipe assembly. Once these items have been bolted down, it’s time to install the intake piping. Can it really be this easy? Indeed! Install the new CCV hose to the engine crankcase vent tube and intake pipe and then place the vacuum plug on the intake manifold vent nipple. Now, install the Turbo oil drain and feed fittings and hoses. Congratulations! That’s it!

The entire installation takes about an hour. Honestly, I may have left out a step or two but come on, it’ll take two hours max, if you’re totally unfamiliar with the tractor.

We made one rookie mistake regarding the design and fabrication of the intake charge pipe. We didn’t account for the hood prop-rod absorber and it cannot be reinstalled with the intake charge pipe in place, which means, no hood opening assist. Whoops! So, we’ll have to eventually redesign and fabricate a new pipe sometime in the near future. Shouldn’t be a big issue but, in the meantime, I’m using a shortened broomstick handle to keep my hood open when necessary. That’s the spirit!

Ohhh, that’s right, I forgot one very important step required to complete the Turbo system installation. The fuel adjustment screw. Place palm on forehead. Unfortunately, this simple step can easily double the overall installation time.

By design, it’s not easy to gain access to the fuel adjustment screw. Kubota does not want you to do it, period. Tier 4 emissions, remember? The screw itself is hidden within a thick, heavy tamper proof protective security cover to prohibit access. Those of us that have ventured to remove this cover have found that it’s easiest to use a dremel. This is also the point of no return. Your warranty (if applicable) ends here.

It takes a bit of time cutting through the thick steel but, eventually, once you cut through the cover you’ll be able to get a flat head screwdriver inside the notch you made in the metal and twist off the cover. With the cover removed, fuel adjustments are quick and easy. Turn counterclockwise to increase fuel delivery and clockwise to decrease fuel delivery. It’s that simple.

With the entire Turbo system installed and the fuel set screw accessible, it was time for some impressions and subsequent testing.

I gotta tell you, Turbo sounds combined with Diesel engine clatter are music to my ears. They’re made for each other. It’s like icing on a cake! The L2501 Turbo literally sounds like a mini-Cummins Diesel engine. Or, if you’re a Ford fan, a tiny 7.3L PowerStroke diesel. It’s hilarious. You can hear the turbo spool up and flutter down with throttle adjustments. Very cool!

How loud is it? There’s no muffler on that thing! Are you crazy? What about the noise? Shockingly, even without a muffler, it’s not loud. It’s about the same noise volume as stock, perhaps a tiny bit louder. The Turbo itself acts as a muffler for the exhaust and I believe using the OEM Kubota intake assembly instead of an aftermarket air filter, also helps with the overall noise volume. I haven’t felt the need to use ear protection while running the tractor. Realistically, when you think about it, why would I bother? I want to hear all of the new wonderful Turbo noises. It would be a sin to muffle these pleasing sounds. Right!

With the Turbo system installed and the tractor running smoothly the time has arrived to see what this machine can do. Let’s get to work!

The L2501 Turbo Kit is ready for testing and tuning!

To accomplish this task, I’ll be using a Pyrometer and digital gauge to analyze the exhaust gas temperatures. Why do we care about EGT’s again? What do they tell us? We’re using a pyrometer to test and tune the engine because the EGT is an indication of how hot the combustion process is in the cylinders and the amount of “after burning” that is occurring in the exhaust manifold. The pyrometer measures these conditions in real time. The EGT is also directly related to the air/fuel ratio and the general consensus is the leaner the air/fuel ratio is, the lower the EGT. And the richer the air/fuel ratio is, the higher the EGT will be. Therefore, in most cases, excessively high EGT’s means over fueling. Meanwhile keeping the EGT’s a bit leaner, will lower EGT’s and can actually improve fuel economy. Something to keep in mind. Most diesel experts recommend a maximum of 1,200-1,300 degrees of EGT for regular operation and emphasize that you do not want to maintain temperatures above 1,300 degrees for any extended periods of time.
In theory, by using a Turbo to increase air flow in a diesel engine, fuel can be added in a calibrated manner to increase power while maintaining an acceptable air/fuel ratio that does not create excessive EGT’s. That’s the objective.

It wouldn’t be fair if I didn’t include a baseline EGT test. So, without further delay here are the EGT readings I recorded when 100% stock.

L2501 HST 4WD (LA525 Loader w/ 66” QA Bucket, Liquid Tire Ballast) - ALL STOCK, NO MODIFICATIONS (40* ambient temperature).

Recorded EGT’s:
Idle = 200-300*
Traveling on flat ground (M) = 300-500*
Loader and grading work (M) = 500-700*
Traveling up hill carrying medium load (22* Slope, 40% grade) (M) = 600-738*
Peak EGT = 738*

Now, let’s compare the Turbo EGT’s but, with the factory fuel setting. NO ADDITIONAL FUEL HAS BEEN ADDED. We just installed the Turbocharger system and ran the tractor.

L2501 HST 4WD (LA525 Loader w/ 66” QA Bucket, Liquid Tire Ballast) - MHI TD025 TURBO SYSTEM - 4PSI - Factory Fuel Setting (83* ambient temperature).

Recorded EGT’s:
Idle = 250-275*
Traveling on flat ground (M) = 275-500*
Loader and grading work (M) = 500-625*
Traveling up hill carrying medium load (22* Slope, 40% grade) (M) = 575-700*
Peak EGT = 700*

As you can see, nothing really has changed. The EGT’s heat up a bit quicker but, overall, the temperatures are running around 0-75 degrees cooler with the Turbo installed combined the factory fuel setting. I’m assuming this is because there is more air getting forced into the engine with the same fuel volume. Right now, with the Turbo and factory fueling, there is zero smoke coming from the engine, regardless of conditions. The engine is consuming all the fuel it can get and begging for more.

We’re just getting warmed up!
Let’s add some fuel!

I started with a 1/2 Turn, counter clockwise to increase fuel volume. This setting resulted with a peak of 6 PSI and 3 PSI of sustained boost pressure. No smoke was observed during testing and surprisingly, EGT’s dropped under load going up the hill in (M) gear. Strangely, maximum EGT observed was 631 degrees. Weird.

More puzzling, I wasn’t happy seeing only 3 PSI of sustained boost pressure. I began questioning why I wasn’t maintaining more boost pressure. Was it fuel? Or, was it some issue related to the Turbo system? At this moment I started questioning the capacity of the OEM intake assembly and air filter. Could it flow enough air for the Turbocharger? I quickly removed the OEM intake assembly and ran the Turbo open-air (no filter) to see if the factory air intake assembly was causing a restriction.

The tractor did in fact pick up an additional 1 PSI of boost both peak and sustained with the same fuel setting, but only 1 PSI. 1 PSI isn’t monumental. This proved a few things; one, using the OEM air cleaner assembly and filter is perfectly acceptable. Two; with such a small gain in boost pressure, it isn’t worth using an aftermarket performance air filter, especially considering the air filtration issues I experienced previously. And three; I need more fuel. I reinstalled the OEM air cleaner assembly and prepared for additional testing.

I gradually increased the fuel volume to 1 full turn, counter clockwise. This setting resulted with 7 PSI peak and 4 PSI sustained boost pressure. No smoke was observed during testing. That’s not enough sustained PSI. I still wasn’t pleased with the results.

L2501 HST 4WD (LA525 Loader w/ 66” QA Bucket, Liquid Tire Ballast) - MHI TD025 TURBO SYSTEM - 7 PSI - Fuel setting, 1 Full Turn (75* ambient temperature).

Recorded EGT’s:
Idle = 275-300*
Traveling on flat ground (M) = 300-500*
Loader and grading work (M) = 500-630*
Traveling up hill carrying medium load (22* Slope, 40% grade) (M) = 500-640*
Peak EGT = 640*

I then increased the fuel volume to 1 1/2 turn, counter clockwise. This setting resulted with the same 7 PSI peak but, 5 PSI sustained. Now we’re getting somewhere! There was some smoke observed at startup and a puff or two during operation. Not bad. I was happy to be making progress, but, still unhappy with the results.

L2501 HST 4WD (LA525 Loader w/ 66” QA Bucket, Liquid Tire Ballast) - MHI TD025 TURBO SYSTEM - 7 PSI - Fuel Setting, 1 1/2 Full Turns (82* ambient temperature).

Recorded EGT’s:
Idle = 250-300*
Traveling on flat ground (M) = 300-500*
Loader and grading work (M) = 500-630*
Traveling up hill carrying medium load (22* Slope, 40% grade) (M) = 500-641*
Peak EGT = 641*

Shockingly, the numbers really aren’t that different. Why? I just can’t place enough load on the tractor to make it work hard enough to sustain boost pressure. Even going up my big hill in (M) gear carrying a load isn’t enough to maintain a load on the tractor. Crazy!

My testing parameters are flawed.

Luckily, a forum member reached out to me with a remedy. He suggested to run the tractor up against an unmovable object to create a heavy load on the tractor. Ahhh, that makes sense! He also suggested adding even more fuel. Done! In addition to his suggestions, I decided to add a new test too. Going up my hill in (H) gear carrying a load! Two new tests! Let’s see what we have now.
The results came pouring in!

L2501 HST 4WD (LA525 Loader w/ 66” QA Bucket, Liquid Tire Ballast) - MHI TD025 TURBO SYSTEM - 9 PSI - Fuel Setting, 2 Full Turns (64* ambient temperature).

Recorded EGT’s:
Idle = 250-300*
Traveling on flat ground (M) = 300-500*
Loader and grading work (M) = 500-680*
Traveling up hill carrying medium load (22* Slope, 40% grade) (M) = 500-640*
Traveling up hill carrying medium load (22* Slope, 40% grade) (H)= 500-779*
Immovable object = 985*
Peak EGT = 985*

More is better. I increased the fuel volume to 2 1/4 turn, counter clockwise. This setting resulted with 10 PSI peak and 8 PSI sustained boost pressure. There is some smoke observed at startup and a puff or two during operation, but there is no visible smoke under full load. In all seriousness, the tractor is begging for even more fuel. I swear there’s more boost pressure and more power to be unlocked. No doubt. However, we’re recording just over 1000 degrees peak EGT and that’s right where I want to be and that’s as far as I’m going (for now).

L2501 HST 4WD (LA525 Loader w/ 66” QA Bucket, Liquid Tire Ballast) - MHI TD025 TURBO SYSTEM - 10 PSI - Fuel Setting, 2 1/4 Full Turns (78* ambient temperature).

Recorded EGT’s:
Idle = 250-300*
Traveling on flat ground (M) = 300-500*
Loader and grading work (M) = 500-730*
Traveling up hill carrying medium load (22* Slope, 40% grade) (M) = 500-650*
Traveling up hill carrying medium load (22* Slope, 40% grade) (H) = 500-812*
Immovable object = 1,033*
Peak EGT = 1,033*

Overall, I’m very pleased with this setting and the performance I’m feeling. The L2501 Turbo, is awesome!

Whatever bro. EGT measurements, testing and comparisons blah, blah, blah, blah, blah.
Are there any performance gains with the Turbo installed? Does the tractor work better? Can it do more stuff?

It’s gonna be a minute before I can get my tractor to a PTO dyno. However, I can share the perceived gains I’ve experienced with the Turbo system installed.

Initially, I was expecting more overall performance. I assumed the tractor would behave similar to a car or truck equipped with a Turbocharger setup and would produce additional power in all working conditions, even without a load. But, that’s obviously not the case as illustrated with the final EGT tests. The tractor has to be under a heavy sustained load for the Turbo to really function. So, while driving and operating the tractor in normal conditions, you really can’t feel any difference. Literally, 90% of the time doing minor tasks, it feels like a completely stock L2501, which isn’t a bad thing. But, when you need power, it’s there!

L2501 vs Hill.

First and foremost, having the ability to carry heavy loads up my big hill in (M) gear was an important consideration for improvement and a specific task my tractor continually struggled with incessantly. With the Turbo installed, the L2501 has zero issues carrying a heavy load up this hill in (M) gear. At 2,200 RPM the tractor maintains speed and boost pressure all the way up and over the hill. The RPM’s remain constant and the L2501 absolutely refuses to bog down regardless of the load it’s carrying. It’s a relief knowing I no longer have to crawl up this hill. With (M) gear functioning to my expectations, (L) gear is no longer needed. My L2501 Turbo has conquered the big hill and that makes me a very happy operator.

Pushing the envelope, I decided to run my tractor up my big hill carrying a load in (H) gear. In all seriousness, this was a stupid test. The path up the hill isn’t made for speed. It’s uneven and rocky. Trying to go fast isn’t wise. But, I had to give it a shot. For the first time ever, the tractor was able to climb the hill in (H) gear. But, it wasn’t pretty, about halfway up the hill, the Turbo dropped boost pressure, the tractor bogged down and I lost speed and momentum. Regardless, the tractor didn’t give up and it made it to the top of the hill to deliver a load of large branches to my brush pile. In (H) gear? That’s a first! Nemesis no more! The L2501 Turbo is a beast!

Another important consideration was transportation speed in (H) gear. I’m pleased to report the L2501 Turbo can maintain ground speed on flat and hilly paved surfaces and I have full use of (H) gear for transportation purposes. The tractor hilariously takes off rapidly from a stop and accelerates to top speed almost instantly and continues to maintain speed without issue. The tractor shows no sign of bogging down. The Turbo will immediately deliver 9-10 PSI and slowly taper off to 5-6 PSI because the load drops off very quickly after take off. There’s just not enough load without doing actual work to sustain boost pressure.

The L2501 Turbo powers my wood chipper in heroic fashion. During my testing, the tractor didn’t bog down once and it chipped everything I could stuff down the shoot, including whole saplings. There’s some serious power coming from the PTO, it is performing exceptionally well.

Overall, I have not logged nearly enough time on the Turbo system to provide any full conclusions. So, those revelations will come in time. What I can say is that I added the Turbo system to produce more power in challenging conditions. It has in fact delivered.

I know at the end of the day, most of us aren’t in a hurry to get our tractor work done quickly. Our tractors and the work we do with them, is our therapy.
However, I know there are times, when I’ve been on the tractor all day long and it’s starting to get late. The sun is beginning to set and I only have a few more buckets of material to move, a couple more brush piles left to transfer, a small pile of branches left to chip, an acre left to mow, a half acre left to grade, or a quarter acre left to till, a little more power and a little more speed wouldn’t hurt.
Thankfully, I have an L2501 Turbo to do the job.

Sometime in the near future, when the opportunity presents itself, I will be putting my L2501 on the PTO dyno to finalize the results and testing of my L2501 Turbo system. Until then, we’ll continue discussing; the Tractor, the Comparison, the Modification and the Results.

Thank you for reading.

Mike

 

[Rdrcr]

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 excuses. No blather. No guessing. No subjective observations. 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. 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.

You see, I was in desperate need to find this particular piece of equipment because a PTO dynamometer measures a tractor’s performance by applying a calibrated and controlled braking force on the tractor’s 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 and quite necessary to prove, or disprove the actual performance of my Turbocharged L2501.

I contacted countless tractor service facilities outside of my local area searching 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 dismissed. Refusing to give up I continued to probe and collect clues from potential service facilities inquiring 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 consistent and cool 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 service 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 tractor, 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. 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?

However, maximum power wasn’t our goal. My limiting factor during the testing was EGT temperature. I didn’t want to see the EGT’s climb over 1,200 degrees during sustained operation on or off the PTO Dyno. Instead of seeking maximum power, we took a conservative approach. We didn’t want to maximize the potential of the turbo system. We wanted to meet our goals safely, without compromising any components, or placing any undue stress on the engine, or tractor. We want this Turbo system to deliver exceptional performance and trouble free operation for the life expectancy of the powertrain.

Speaking about reliability, durability and longevity. I’m aware of the skeptics out there. What will it take to convince those individuals that adding a Turbocharger system to an originally N/A (naturally aspirated) diesel engine can be done safely, reliably and durably, for years to come? Good question. What will it take to silence the skeptics? 200 hours of trouble free operation? 500 hours? 1,000 hours? 3,000 hours? A full 5,000 hours? I don’t know.
I can say that every precaution with regards to the engineering and design of the Turbo system to ensure reliability and preserve longevity of the engine, the Turbocharger setup and the tractor has been made. None of us want to harm our tractors, or be burdened with expensive repairs, or downtime.

Seriously, if you’re not adverse to modifying your tractor and you want more power, you may want to consider a L2501 Bolt-on Turbo kit.

To sum up, I think it’s safe to say the Turbocharged L2501 is in a class of its own! You simply cannot beat the cost, or the performance this tractor is delivering.
When we consider the total tractor investment and want to compare PTO productivity for your money, if you recall, the standard L2501 costs you $963 per PTO HP. The L3901 / L3902 delivers a much more reasonable $754 / $860 per PTO HP. An L2501 with the ‘FREE’ injection pump timing modification emerges with a delightful $733 per PTO HP, besting the L3901 / L3902 but, unfortunately, without matching the power output.
The L2501 equipped with this Turbo kit, easily trounces the performance output of the L3901 / L3902 while also delivering an outstanding $595 per PTO HP! It’s the obvious PTO HP per dollar champion! All the while saving you $2,234 on a L3901 and $4,487 on the L3902 tractor purchase. That’s money that could be used towards purchasing much needed implements!

Frankly, adding this Turbo kit to the L2501 makes all the other comparable Kubota Standard L Series tractors pretty much irrelevant. The L2501 tractor appropriately modified, can meet, or exceed the performance of all the other equivalent Kubota Standard L Series tractors. The L2501 can literally do it all.

Lastly, if you own an L2501 (or you are considering an L2501 tractor in the future) and think you might need more power sometime down the road, or additional power now, for high altitude operation, additional power for running and driving larger PTO driven implements like rotary cutters, snowblowers, flail mowers, finish mowers and rotary tillers in demanding conditions and/or challenging terrain, powering larger wood chippers, PTO generators, or post hole diggers, need additional operating speed and pulling power for larger, heavier dirt working ground engagement implements, more power for traversing steep terrain, and/or higher ground speeds in (H) gear on hills, and a cost savings over factory tractor options, this is your ticket! Whew, that was a mouthful!

The L2501 Turbo is unquestionably, the definitive answer to an expensive tractor upgrade and it is without a doubt, the ‘Hot Rod’ solution to a hobby farmer’s quandary. I think I found my perfect tractor!

Thanks again for reading and let the discussion begin.

Mike

 

[Rdrcr]

Mike

 

[Rdrcr]

Mike

 

[jjeff]

Impressive modification nice upgrade from 19- 35pto hp with a hydrostatic transmission curious to know what parts of the 2501 drive line and pto are interchangeable with other L series tractors of similar years?

 

[tacticalturnip]

This is a really good read, thank you for posting it! I'm only through part one, but I'm enjoying the thread so far.

 

[5030]

I would have just bought a larger tractor myself.

 

[oldballs]

I would have just bought a larger tractor myself.

Who asked 'ya