JACOB WHITE
.
October 24, 2018
.
Latest
THE POPULARITY OF diesel-powered vehicles here in the U.S. has jumped dramatically in recent years. More and more manufacturers are offering new diesel power plants in ½-ton trucks, cars and midsize SUVs. Maybe the reasons for the boost are better highway fuel efficiency and the giant increase in torque offered by a diesel engine, but it’s probably an attempt to meet everincreasing CAFE (Corporate Average Fuel Economy) numbers. Either way, these smaller V-6 and four-cylinder engines will be sticking around. But back in the day, it was Cummins that developed its own small diesel engine market with the 3.9L 4BT.
The 4BT—which stands for “fourcylinder B series turbocharged”— was used mostly in midsize box trucks, agricultural equipment and small industrial vehicles, and is basically a smaller version of the popular 5.9L 12V Cummins found in 1989-98 Dodge trucks. The 4BT shares virtually all of its parts with its big brother, the 6BT (e.g. pistons, connecting rods, injectors and valve-train design).
The major internal difference comes from the lack of two cylinders, which means two fewer journals on the crankshaft, a shorter camshaft, two fewer pistons in the injection pump, etc. But even these pieces are the same as the 6BT, just in an inline four-cylinder version. Because of these similarities, the 4BT Cummins has an extremely strong aftermarket, since many 5.9L 12V performance parts can be used in smaller 3.9L engines. This, paired with the somewhat compact size of the 4BT, makes it a great candidate as a transplant engine for just about any vehicle. We’ve seen 4BTs in everything from Jeeps to old-school rat rods. The simplicity of the mechanical injection system also helps make it an easy swap because there’s little to no wiring or electronics required.
Since the engine was originally developed for industrial applications, big horsepower wasn’t a major concern, and the 239-cid motor most commonly came from the factory at around 105 hp at 2,300 rpm and 265 lb-ft of torque at 1,600 rpm. But these numbers could vary as much as 150 hp depending on the application.
The 4BT engine weighs 750- 780 pounds, which is heavier than most of the gas engines it would replace in a conversion project, but much lighter than the sixcylinder 6BT version. The inlinefour also offers a fairly compact size at just 30.6 inches long and 37.7 inches tall, which is useful with space constraints. The engines came with a few different injection pump systems, but the P7100 is, by far, the most popular, since it’s capable of producing larger amounts of fuel and more easily modified by the aftermarket to increase power outputs.
As previously mentioned, the 4BT can easily be modified to produce higher than stock power levels when outfitted with the P7100 (P-pump). Fueling mods can be taken to the same extremes as with the 5.9L 12V Cummins: 12mm and 13mm pumps with laser-cut delivery valves, high-rev governor springs, full-travel rack plugs and modified injectors can all be used in the 4BT platform. To go along with major fuel upgrades, common cylinder head and turbocharger upgrades are required, but the aftermarket already has most of that covered as well with head studs, better valve springs, larger valves and even performance exhaust manifolds and camshafts built for four-cylinder diesels. While these upgrades can take the 4BT to all-new levels, we have to mention that because of its lack of cylinders and nearly identical operating rpm range, each piston is going to undergo a combustion cycle much sooner than that in a 6BT Cummins, so things like camshaft profiles and pump timing become critical for maximum efficiency at higher horsepower levels.
Like any engine platform, it’s a well-known fact that more cubic inches generally means more power, and there’s only so much a 239-cid motor can produce, at least safely and efficiently. With this in mind, ACD Engines of Salt Lake City has developed its Stroker Kit to take the 4BT to heretofore unheard of performance heights.
LIKE ANY ENGINE PLATFORM, IT’S A WELL-KNOWN FACT THAT MORE CUBIC INCHES GENERALLY MEANS MORE POWER, AND THERE’S ONLY SO MUCH A 239-CID MOTOR CAN PRODUCE, AT LEAST SAFELY AND EFFICIENTLY.”
Also known locally as “All Cummins Engines,” ACD has been a full-line Cummins dealer for more than 20 years, specializing in midrange and industrial engines. It offers virtually everything Cummins: new or remanufactured engines, new genuine Cummins parts, used engines and even salvage parts. Since it deals in nothing but Cummins, ACD stocks many hard-to-find parts, and if it’s not in stock, the staff knows where to get what you need. Through their years of experience, the staff has become extremely wellversed in the 4BT platform and has the conversion process down to a science, inserting the small Cummins engine into Jeeps, small SUVs, pickups and even a mid- ’50s ambulance.
In the search for more power, owner Robby Pederson began development of a Stroker Kit that would increase the length of stroke and add some additional cubic inches to the inline-four diesel. In the gas world, Stroker engines are nothing new; the GM small-block 383 Stroker engines have been around for nearly 35 years. The 383 is built using a standard GM 350- cid engine block with a modified 400-cid crankshaft, which changes how far the piston travels.
Because the factory 4BT crankshaft is a robust piece, Pederson didn’t want to do much crankshaft work, so he opted for an all-new piston and connecting rod design to gain the additional stroke he was after. A factory 4BT engine runs a 4.02-inch bore with a 4.72-inch stroke; this is how we come to a 239-ci motor. The new parts from ACD will allow the overall piston bore to expand to 4.402 inches with a much longer 5.430-inch stroke, effectively taking engine output to 333 ci, or 5.46L, almost that of the 5.9L 12V Cummins.
Knowing that the clientele for such a kit would be after extreme power levels, only the best materials were used to ensure the ACD Stroker Kit would stand up to high boost and high cylinder pressures. Rather than use standard-cast pistons, like the stock units, ACD went with a much stronger forged piston design that offers a different bowl design to improve the air/fuel swirl effect, helping create a more efficient burn in the combustion chamber. The piston design also has a much shorter overall height, and the wrist pin location was moved closer to the deck. These modifications account for most of the additional stroke.
To match the new piston, connecting rods were developed and made from billet 4340, like those being used in all of the high-horsepower diesel engines. The new H-beam rod design is not only stronger than a factory connecting rod, but it also has a much smaller wrist pin journal, which will only work with the ACD piston. While the pistons and rods are the true heart of the Stroker Kit, ACD has also developed a host of 4BT parts to complement them and ensure true peak performance is achieved. Specific camshaft profiles were designed, custom cylinder head work was done and 4BT-specific adjustable injection pump timing gears were installed. The short time between injection events on the four-cylinder engine required a slight engineering change for these parts, and ACD thinks its developed the perfect pieces to turn your run-of-the-mill 105-hp 4BT into a tire-shredding 800-hp monster.
ACD Engines understands that the complete Stroker Kit might be more than most 4BT project vehicles need, so it has an array of 4BT-specific products that can do everything from increasing power to improving fuel mileage and engine efficiency. It also carries a full line of custom brackets and conversion pieces to make your conversion or transplant project go a little easier.
• ACD Engines
877.506.8667
Acdengines.com
Are there more modern diesel engine options that might be better choices than the 3.9L Cummins?
Absolutely, there are various modern diesel engine options that might be superior choices compared to the 3.9L Cummins.
Modern diesel engines often come with advancements that offer:
In summary, while the 3.9L Cummins is reliable, newer diesel engines like the Duramax 3.0L, Power Stroke 3.2L, and EcoDiesel 3.0L come with significant benefits that make them worth considering.
What are some drawbacks of the 3.9L Cummins engine?
The 3.9L Cummins engine, while rugged and reliable, comes with several drawbacks that potential users should consider.
In summary, the 3.9L Cummins provides durability but falls short in areas of refinement, noise levels, and ease of tuning. Assess your priorities and resources before committing to this engine.
Why might fuel economy not be a sufficient reason to swap to a 3.9L Cummins engine?
Swapping to a 3.9L Cummins engine might seem enticing for those looking to improve fuel economy, but this consideration alone may not be sufficient to warrant the conversion. Here’s why:
The 3.9L Cummins engine is quite heavy, weighing about a third of a Jeep Wrangler. This added mass can negatively affect the vehicle’s handling and overall performance. Moreover, the increased weight places additional stress on the suspension and axles, potentially leading to more wear and tear, especially in smaller vehicles like Jeeps.
Both the 4BT and 4BTA variants are non-intercooled, turbo-diesel engines. While this eases installation by eliminating the need for intercooler ducting, enhancing performance will likely require you to add an intercooler. Fitting this component under the hood can be challenging and may require substantial modifications.
The potential fuel savings vary significantly based on the engine you are replacing. For instance, if your current vehicle averages around 15 miles per gallon, you might not see substantial savings since post-conversion fuel efficiency tends to range between 17 and 21 mpg. This marginal improvement may not justify the costs associated with the engine swap, making it harder to recoup your investment through fuel savings alone.
For heavier trucks and SUVs, the weight added by the 3.9L Cummins engine might not be as critical an issue compared to smaller 4x4s. Weight becomes a relative challenge in heavily modified off-road vehicles, where handling and stress distribution are more crucial.
While improving fuel economy is certainly appealing, it shouldn’t be your sole reason for swapping to a 3.9L Cummins engine. The added weight, potential handling issues, the need for additional components, and modest fuel savings make it essential to weigh all factors before committing to such a conversion. Consider looking at the complete picture, including how the weight and stress impact your specific vehicle type and your particular use case, before making this significant modification.
What are the typical fuel economy figures for vehicles with a 3.9L Cummins engine swap?
When swapping a 3.9L Cummins engine into a vehicle, fuel economy typically falls within a certain range. Real-world data suggests that you can expect between 17 and 21 miles per gallon (mpg).
However, these figures are influenced by various factors, including:
In essence, while the 3.9L Cummins engine offers a broad range of fuel efficiency, specific results will vary based on how and where you drive.
What types of vehicles are better suited for the 3.9L Cummins engine swap?
The 3.9L 4BT Cummins diesel engine has become an extremely popular platform for conversion projects throughout the past couple of years, and for good reason. Sharing virtually every internal and external piece with its big brother, the 5.9L 12V Cummins found in the 1989-98 Dodge Ram pickups, and coming as regular equipment in hundreds of commercial and industrial applications, parts availability, power potential, fuel mileage, and the lack of electronics make it an easy go-to engine when it’s time to squeeze a diesel platform into the frame rails of just about anything.
The major internal difference comes from the lack of two cylinders, which means two fewer journals on the crankshaft, a shorter camshaft, two fewer pistons in the injection pump, etc. But even these pieces are the same as the 6BT, just in an inline four-cylinder version. Because of these similarities, the 4BT Cummins has an extremely strong aftermarket, since many 5.9L 12V performance parts can be used in smaller 3.9L engines. This, paired with the somewhat compact size of the 4BT, makes it a great candidate as a transplant engine for just about any vehicle. We’ve seen 4BTs in everything from Jeeps to old-school rat rods. The simplicity of the mechanical injection system also helps make it an easy swap because there’s little to no wiring or electronics required.
When it comes to engine swaps, the 3.9L Cummins is definitely worth bringing to the table. If you have a full-size application, such as trucks or larger SUVs, the 4BT isn’t a bad option. It’s particularly appealing if you’re looking to build a reliable overland-type rig that can handle long-distance travel and rough terrain.
For more compact and nimble vehicles, like the Jeep Wrangler, the 3.9L Cummins might not be the best option. The weight and size of the engine could affect the vehicle’s handling and performance. There are better-suited engine options for these kinds of vehicles, which are designed to maintain their agility and off-road capabilities.
In summary, the 3.9L 4BT Cummins diesel engine offers a versatile and robust option for a variety of vehicle conversions but shines brightest in full-size vehicles where its power and simplicity can be fully utilized. Whether you’re working on an overland rig or a custom build, understanding the suitable applications for this engine can help you make the best choice for your project.
Can the 3.9L Cummins engine’s power be increased, and what does it entail?
The 4BT can easily be modified to produce higher than stock power levels when outfitted with the P7100 (P-pump). Fueling mods can be taken to the same extremes as with the 5.9L 12V Cummins: 12mm and 13mm pumps with laser-cut delivery valves, high-rev governor springs, full-travel rack plugs, and modified injectors can all be used in the 4BT platform. To go along with major fuel upgrades, common cylinder head and turbocharger upgrades are required, but the aftermarket already has most of that covered as well with head studs, better valve springs, larger valves, and even performance exhaust manifolds and camshafts built for four-cylinder diesels.
While these upgrades can take the 4BT to all-new levels, we have to mention that because of its lack of cylinders and nearly identical operating rpm range, each piston is going to undergo a combustion cycle much sooner than that in a 6BT Cummins, so things like camshaft profiles and pump timing become critical for maximum efficiency at higher horsepower levels.
However, it’s important to note that the 4BT is not a modern diesel. In fact, it’s a bit antiquated and unrefined. For some, the rattle, shake, and noise of this diesel will be too much. These characteristics can be a significant drawback if you’re looking for a smoother, quieter ride.
Additionally, you can’t simply hook a programmer to a 4BT and voila—you have 500hp. Yes, you can turn up the power, but it’s going to take real work and a serious investment of funds to get the numbers into the bragging realm. This means that while the 4BT has a lot of potential, prospective modifiers should be prepared for the commitment in both time and money.
By understanding these limitations and the extent of modifications necessary, you can better assess whether the 4BT is the right platform for your performance goals.
How does the weight of the 3.9L Cummins engine affect vehicle handling and suspension?
The 4BT engine weighs 750-780 pounds, which is heavier than most of the gas engines it would replace in a conversion project, but much lighter than the six-cylinder 6BT version. The inline-four also offers a fairly compact size at just 30.6 inches long and 37.7 inches tall, which is useful with space constraints.
However, this added weight can put more strain on the vehicle’s suspension and axles. For full-size trucks or SUVs, the weight won’t be as much of an issue due to their robust build. Weight is often relative when it comes to heavily modified 4x4s, meaning the impact can vary significantly based on the level of modification.
This nuanced understanding helps in making informed decisions when considering a 4BT engine conversion, ensuring vehicle handling and suspension are adequately addressed.
How do the pre-1998 and post-1998 3.9L Cummins engines differ in terms of valves and power output?
“The 4BT engine uses a simple two-valve-per-cylinder system, one for intake and one for exhaust. While this design became somewhat outdated with the introduction of the four-valve-per-cylinder design found in the 1998.5-plus 6BT engines, it’s still a sufficient and robust design, especially on the smaller cubic inch, low 130-180-hp applications for which most of the 4BT engines were designed.
Pre-1998 4BT engines feature an eight-valve configuration, delivering power ratings of 105hp and 265 lb-ft of torque. However, post-1998 units, known as the 4BTA, transitioned to a 16-valve setup. This valvetrain adjustment resulted in a significant base horsepower increase to 170hp and a more impressive 420 lb-ft of torque. Power figures can vary depending on the application, but the enhancements made in the post-1998 models are evident.
In summary, while the 4BT’s two-valve-per-cylinder system remains effective for its intended applications, the advancements seen in the 4BTA models demonstrate the benefits of increased valve counts and improved power output. This evolution highlights the ongoing improvements in engine design to meet higher performance demands.”
What are some common applications for the 3.9L Cummins engine?
The 4BT—which stands for “four-cylinder B series turbocharged”—was used mostly in midsize box trucks, agricultural equipment, and small industrial vehicles, and is basically a smaller version of the popular 5.9L 12V Cummins found in 1989-98 Dodge trucks. The 4BT shares virtually all of its parts with its big brother, the 6BT (e.g., pistons, connecting rods, injectors, and valve-train design).
Hitting the market in 1983, the first 3.9L Cummins (known as the 4BT) has been used in everything from delivery trucks to wood chippers. This means they can be found anywhere, and for really cheap. The 3.9L 4BT Cumminsdiesel engine has become an extremely popular platform for conversion projects throughout the past couple of years, and for good reason. Sharing virtually every internal and external piece with its big brother, the 5.9L 12V Cumminsfound in the 1989-98 Dodge Ram pickups, and coming as regular equipment in hundreds of commercial and industrial applications, parts availability, power potential, fuel mileage, and the lack of electronics make it an easy go-to engine when it’s time to squeeze a diesel platform into the frame rails of just about anything.
The major internal difference comes from the lack of two cylinders, which means two fewer journals on the crankshaft, a shorter camshaft, two fewer pistons in the injection pump, etc. But even these pieces are the same as the 6BT, just in an inline four-cylinder version. Because of these similarities, the 4BT Cummins has an extremely strong aftermarket, since many 5.9L 12V performance parts can be used in smaller 3.9L engines. This, paired with the somewhat compact size of the 4BT, makes it a great candidate as a transplant engine for just about any vehicle. We’ve seen 4BTs in everything from Jeeps to old-school rat rods. The simplicity of the mechanical injection system also helps make it an easy swap because there’s little to no wiring or electronics required.
The 4BT engine has been used in commercial utility trucks and industrial construction equipment since the late-’80s, and because of its extremely basic functionality, it works well as a transplant engine when space is tight.
Why is the 3.9L Cummins engine popular for engine swaps?
The 3.9L 4BT Cummins diesel engine has become an extremely popular platform for conversion projects throughout the past couple of years, and for good reason. Sharing virtually every internal and external piece with its big brother, the 5.9L 12V Cummins found in the 1989-98 Dodge Ram pickups, and coming as regular equipment in hundreds of commercial and industrial applications, parts availability, power potential, fuel mileage and the lack of electronics make it an easy go-to engine when it’s time to squeeze a diesel platform into the frame rails of just about anything.
Why the 3.9L Cummins is a Top Choice for Swaps
These figures show that despite its relatively compact size, the 3.9L Cummins packs a punch, making it perfect for a variety of conversion projects.
First hitting the market in 1983, the 3.9L Cummins, also known as the 4BT, has been utilized in everything from delivery trucks to wood chippers. This widespread use means the engines are not only easy to find but also affordable. Their robust design and mass availability make them a practical choice for enthusiasts looking for reliability without breaking the bank.
One of the standout features of the 3.9L Cummins is its minimal reliance on electronics. This simplicity significantly eases the conversion process, allowing for a smoother integration into various projects. Whether you’re dealing with an older vehicle or a custom build, fewer electronics mean fewer complications.
The engine’s compatibility with a slew of manual and automatic transmission options adds another layer of versatility. It allows for a wide range of applications, catering to different needs and preferences.
Sharing much of its DNA with the revered 5.9L 12-valve Cummins, the 3.9L offers a similar promise of durability and reliability. This connection gives diesel enthusiasts confidence that the engine can withstand the test of time and usage.
In conclusion, while there might be other diesel options out there, few can match the 3.9L Cummins in terms of cost-effectiveness, ease of conversion, and overall reliability. It’s no wonder this engine remains a favorite among those looking to undertake conversion projects.
How much power and torque does the 3.9L Cummins engine produce?
The engine was originally developed for industrial applications, big horsepower wasn’t a major concern, and the 239-cid motor most commonly came from the factory at around 105 hp at 2,300 rpm and 265 lb-ft of torque at 1,600 rpm. But these numbers could vary as much as 150 hp depending on the application.
One diesel engine in particular that pops up more than most is the 3.9L Cummins. The 3.9L (4BT) Cummins inline-four diesel engine creates 105 hp and 265 lb-ft of torque from its relatively small size of 30.6 inches long, 24.6 inches wide, and 37.7 inches high.
Depending on the application, the power figures can vary, making this engine versatile for various uses.
What are the pros and cons of the 3.9L Cummins (4BT) diesel engine?
The 3.9L 4BT Cummins diesel engine has become an extremely popular platform for conversion projects throughout the past couple of years, and for good reason. Sharing virtually every internal and external piece with its big brother, the 5.9L 12V Cummins found in the 1989-98 Dodge Ram pickups, and coming as regular equipment in hundreds of commercial and industrial applications, parts availability, power potential, fuel mileage, and the lack of electronics make it an easy go-to engine when it’s time to squeeze a diesel platform into the frame rails of just about anything. Because of these similarities, the 4BT Cummins has an extremely strong aftermarket, since many 5.9L 12V performance parts can be used in smaller 3.9L engines. This, paired with the somewhat compact size of the 4BT, makes it a great candidate as a transplant engine for just about any vehicle.
Overall, the 3.9L Cummins diesel engine stands out for its mass availability, simplicity, and versatility. However, it is important to weigh these advantages against its drawbacks, particularly the added weight and lack of modern refinements. If you’re considering an engine swap, the 3.9L Cummins offers a robust and reliable option, especially for full-size applications. For smaller, more nimble vehicles, you may want to explore other alternatives.
What are some of the common issues and reliability concerns with the Cummins 4BT engine?
The Cummins 4BT engine, though praised for its durability, comes with a set of issues and reliability concerns that potential users should be aware of.
One of the primary challenges with the 4BT engine is its physical size. It’s a bulky and heavy engine, making installation in smaller vehicles quite difficult. The engine’s significant weight can strain the front suspension of smaller 4×4 vehicles, leading to handling issues and potentially increased wear and tear on the suspension components.
The 4BT is notorious for being loud and shaky. This characteristic is typical of older diesel engines and can be quite uncomfortable for those accustomed to more modern, quieter engines. The noise and vibration can also be a concern for long-term use, potentially leading to cabin discomfort and increased fatigue during extended drives.
Another common issue is the level of emissions produced by the 4BT engine. Being an older diesel engine, it tends to release more smoke compared to newer models. This can be a significant drawback in terms of environmental impact and may not meet modern emissions standards without additional modifications.
While the 4BT is robust, it doesn’t always provide enough power for larger vehicles, such as full-size trucks or SUVs. Users looking to install this engine in such vehicles may find its performance lacking, particularly in demanding driving conditions.
The installation process can be quite complex due to the engine’s need for additional components like an intercooler and associated piping. This not only makes the installation more labor-intensive but can also increase the overall cost.
In summary, while the Cummins 4BT engine is known for its simplicity and ease of repair, potential users should consider its size, noise levels, emissions, and power limitations. Ensuring proper installation and accommodating for its physical and mechanical characteristics can help mitigate some of these concerns, but it’s crucial to weigh these factors against the engine’s benefits before making a decision.
What are the challenges of installing a Cummins 4BT engine in a small vehicle?
Installing a Cummins 4BT engine in a small vehicle comes with several significant challenges:
Overall, these factors make the installation of a Cummins 4BT engine in a small vehicle a complex and often impractical endeavor.
What is the difference between the 4BT and 4BTA versions of the Cummins engine?
When examining the distinctions between the 4BT and 4BTA versions of the Cummins engine, several key aspects come into play, particularly in their injection and cooling systems.
In summary, the primary distinctions between the 4BT and 4BTA versions are centered around their cooling systems and resulting performance capabilities. The addition of an intercooler in the 4BTA significantly boosts its efficiency and power output, making it the preferred option for more intense industrial uses.
What are the different versions of the Cummins 4BT engine?
The Cummins 4BT engine is a versatile powerhouse with several variations, each designed to optimize performance for specific applications. Here are the primary versions:
In addition to these core versions, automotive charge air-cooled engines from Cummins have varied designations depending on the specific model and production year. This ensures that there is a 4BT variant tailored to nearly every conceivable use-case scenario, from industrial machinery to on-road vehicles.
Understanding these different versions helps in selecting the right 4BT engine to meet your specific requirements, whether for enhanced power, durability, or specialized applications.
Why is the Cummins 4BT engine considered easy to rebuild or repair?
The Cummins 4BT engine is known for its simplicity and ease of maintenance for several key reasons:
In summary, the Cummins 4BT engine’s lack of complex electronics, affordability of parts, straightforward mechanical design, durable construction, and ample documentation contribute to its reputation as an engine that is easy to rebuild or repair.
What are the compression ratios for the different versions of the Cummins 4BT engine?
The Cummins 4BT engine comes in several versions, each with a distinct compression ratio. Here’s a breakdown:
These distinct compression ratios cater to different applications, ensuring that each version of the 4BT engine meets specific performance requirements.
What is the oil capacity and recommended oil change interval for the Cummins 4BT engine?
The Cummins 4BT engine has an oil capacity of 10 quarts (9.5 liters), including the filter.
For optimal performance and longevity, it is advisable to change the oil every 6,000 miles (10,000 kilometers) or every 6 months, whichever comes first.
Regular maintenance helps ensure that the engine runs smoothly and reduces the risk of wear and tear.
Consistent upkeep is crucial to maintaining the reliability and durability of your Cummins 4BT engine.
What materials are used in the construction of the Cummins 4BT engine block and cylinder head?
The Cummins 4BT engine features durable construction materials that contribute to its robust performance. The engine block is made from cast iron, ensuring strong structural integrity. Additionally, the cylinder head is also constructed from cast iron, providing reliability and longevity under high stress and temperature conditions.
These cast iron components are essential for the engine’s durability, allowing it to withstand the rigorous demands often placed on commercial and industrial engines.
What is the firing order of the Cummins 4BT engine?
The Cummins 4BT engine, widely recognized for its efficiency and durability, follows a specific firing order to ensure optimal performance. This four-cylinder turbocharged diesel engine fires in the sequence: 1-3-4-2.
Adhering to this firing order is crucial for maintaining the engine’s balance and smooth operation, minimizing vibrations and ensuring even wear and tear.
By following this established firing sequence, the Cummins 4BT engine operates efficiently, providing reliable power for a variety of applications.
What are some other engines similar to the Cummins 4BT engine?
The 4BT—which stands for “four-cylinder B series turbocharged”—was used mostly in midsize box trucks, agricultural equipment, and small industrial vehicles, and is basically a smaller version of the popular 5.9L 12V Cummins found in 1989-98 Dodge trucks. The 4BT shares virtually all of its parts with its big brother, the 6BT (e.g., pistons, connecting rods, injectors, and valve-train design).
The 4BT and 6BT not only share parts but also the same architecture, making them highly interchangeable. Specifically, the pistons, injectors, connecting rods, valves, pushrods, and rocker arms are identical between the two engines. This level of interchangeability highlights their similarity and utility across different applications.
This shared design makes the 4BT an excellent choice for those familiar with the 6BT, providing a smaller, yet equally robust, alternative.
How does the valvetrain of the Cummins 4BT engine operate?
The 4BT engine uses a simple two-valve-per-cylinder system, one for intake and one for exhaust. While this design became somewhat outdated with the introduction of the four-valve-per-cylinder design found in the 1998.5-plus 6BT engines, it’s still a sufficient and robust design, especially on the smaller cubic inch, low 130-180-hp applications for which most of the 4BT engines were designed.
To understand how the valvetrain operates, it’s important to note that the engine features an OHV (Overhead Valve) system. The camshaft is mounted into the block and is driven by the crankshaft through gears located at the front end of the engine, which also drive the oil pump. This camshaft plays a critical role: it opens and closes the valves by pushing through rocker arms via pushrods and solid tappets.
Despite its simpler two-valve-per-cylinder design, the 4BT engine’s valvetrain remains effective for its intended applications. The camshaft’s precise interaction with the pushrods and rocker arms ensures reliable valve operation, contributing to the engine’s overall durability and performance in specific, lower horsepower uses.
What type of fuel is used in the Cummins 4BT and 4BTA3.9L engines?
The Cummins 4BT and 4BTA3.9L engines are powered by diesel fuel. These engines are renowned for their reliability and efficiency, making diesel the ideal choice for various applications. Diesel not only provides the necessary power and torque for demanding tasks but also ensures optimal performance and fuel economy. Whether used in industrial settings, off-road vehicles, or marine applications, the combination of diesel fuel with these engines delivers durability and consistent power output.
What are the torque specifications for rods, heads, and main components of the Cummins 4BT and 4BTA3.9L engines?
For the Cummins 4BT and 4BTA3.9L engines, ensuring that all components are properly tightened is crucial to their performance and longevity. Here’s a detailed breakdown of torque specifications for key engine components:
By adhering to these specific torque settings, you ensure reliable assembly and optimal performance of these diesel engines. Always remember to follow the precise sequence and incrementations to prevent any damage or distortion of engine components.
What is the main journal diameter for the Cummins 4BT and 4BTA3.9L engines?
The main journal diameter for the Cummins 4BT and 4BTA3.9L engines typically ranges from 3.2672 inches to 3.2682 inches. This precise measurement is crucial for maintaining engine performance and ensuring proper fitment of components. Always check manufacturer specifications to confirm exact measurements for your specific engine model.
What is the rod journal diameter for the Cummins 4BT and 4BTA3.9L engines?
The rod journal diameter for the Cummins 4BT and 4BTA3.9L engines ranges from 2.7160 inches to 2.7170 inches. This precision measurement is crucial for ensuring the proper fit and performance of engine components.
What are the intake and exhaust valve lash specifications for the Cummins 4BT and 4BTA3.9L engines?
If you’re working with the Cummins 4BT and 4BTA3.9L engines, it’s crucial to set the valve lash correctly to ensure optimal engine performance and longevity. Below are the specifications you’ll need for both the intake and exhaust valves:
Proper valve lash settings are essential for several reasons:
Following these specifications will help maintain your engine’s health and performance, ensuring that your vehicle operates smoothly and efficiently.
What is the firing order for the Cummins 4BT and 4BTA3.9L engines?
When dealing with the Cummins 4BT and 4BTA3.9L engines, a critical detail to ensure their smooth operation is understanding their firing order. Both of these engine models follow the same firing sequence, which is essential for optimal performance and engine longevity.
This sequence ensures that the power delivery is balanced and that engine vibrations are minimized, enhancing overall efficiency.
Whether you’re rebuilding an engine, performing routine maintenance, or diagnosing engine issues, knowing this firing order can make a significant difference in the outcome and reliability of your engine work.
What are the specific features of the Cummins 4BT and 4BTA3.9L engine models?
Pre-1998 4BT engines feature an eight-valve configuration, delivering power ratings of 105hp and 265 lb-ft of torque. However, post-1998 units, known as the 4BTA, transitioned to a 16-valve setup. This valvetrain adjustment resulted in a significant base horsepower increase to 170hp and a more impressive 420 lb-ft of torque. Power figures can vary depending on the application, but the enhancements made in the post-1998 models are evident.
Delving deeper into the specifics, the Cummins 4BT and 4BTA3.9L engines are designed with distinct technical features that contribute to their performance and reliability:
These engines are powered by diesel and built with an in-line pump and machined split rods, ensuring robust performance. The pistons are marked with identifiers 8673, 8674, and 8675, signifying specific design and manufacturing details.
For maintenance and tuning, the valve lash settings are critical:
Understanding the torque specifications is essential for engine assembly and repairs:
Finally, the journal diameters are notable for those interested in engine durability:
These technical details illustrate the engineering precision behind the 4BT and 4BTA3.9L models, providing a comprehensive understanding of their capabilities beyond just horsepower and torque.
What are the engine specifications for the Cummins 4BT and 4BTA3.9L models?
Pre-1998 4BT engines feature an eight-valve configuration, delivering power ratings of 105hp and 265 lb-ft of torque. However, post-1998 units, known as the 4BTA, transitioned to a 16-valve setup. This valvetrain adjustment resulted in a significant base horsepower increase to 170hp and a more impressive 420 lb-ft of torque. Power figures can vary depending on the application, but the enhancements made in the post-1998 models are evident.
When diving deeper into the specifications of the Cummins 4BT and 4BTA3.9L models, you’ll discover a suite of technical details that define their robust performance:
Engine Mechanics
Valve and Torque Specifications
Torque Specifications
Journal Diameters
These detailed specifications provide a comprehensive understanding of the engine’s capabilities, ensuring that whether you’re maintaining or upgrading these engines, you’re equipped with the essential information needed to optimize performance.
What is the bore and stroke measurement for the Cummins 4BT and 4BTA3.9L engines?
The factory 4BT engine runs a 4.02-inch bore with a 4.72-inch stroke; this is how we come to a 239-ci motor. However, for those curious about the precise measurements of the Cummins 4BT and 4BTA3.9L engines, you might find it interesting to know that they boast a bore of 4.0165 inches and a stroke of 4.724 inches.
The new parts from ACD will allow the overall piston bore to expand to 4.402 inches with a much longer 5.430-inch stroke, effectively taking engine output to 333 ci, or 5.46L, almost that of the 5.9L 12V Cummins.
This expanded capability illustrates the potential for performance upgrades while maintaining the robust foundation of the original engine specifications. Understanding these measurements not only helps in appreciating the stock engine’s capabilities but also in considering the possibilities for future enhancements.
What is the precise stroke measurement for the Cummins 4BT and 4BTA3.9L engines?
The precise stroke measurement for these engines is 4.724 inches.
What is the precise bore measurement for the Cummins 4BT and 4BTA3.9L engines?
The precise bore measurement for these engines is 4.0165 inches.
What is the life expectancy of a 4BT Cummins engine?
The 4BT engine is renowned for its longevity and robust performance. With proper care and regular maintenance, it can surpass 300,000 miles. This impressive lifespan is a result of its straightforward design, which includes few electronic components.
For optimal performance, key maintenance practices include consistent oil changes, timely replacement of fuel filters, and regular inspections. These steps help maintain the engine’s resilience, making it a reliable choice for commercial uses and custom vehicle projects. With these practices, you can ensure your 4BT engine runs efficiently for many years.
What is the typical fuel efficiency one can expect from a properly tuned 4BT Cummins engine?
Overall, the 3.9L Cummins diesel engine stands out for its mass availability, simplicity, and versatility. However, it is important to weigh these advantages against its drawbacks, particularly the added weight and lack of modern refinements. If you’re considering an engine swap, the 3.9L Cummins offers a robust and reliable option, especially for full-size applications. For smaller, more nimble vehicles, you may want to explore other alternatives.
The 4BT Cummins, known for its impressive fuel efficiency, achieves this through its high compression ratio and efficient turbocharged design. Built for low-RPM, high-torque performance, it delivers power efficiently without burning excessive fuel. Many users report achieving up to 40 miles per gallon with properly tuned 4BT setups, particularly in lighter vehicles.
This level of fuel efficiency makes the 4BT an attractive choice for those looking to optimize for economy without sacrificing performance. As you assess your options for engine swaps, the potential fuel savings with the 4BT Cummins might be a compelling factor to consider, especially if mileage is a priority in your decision-making process.
How does the 4BT Cummins engine deliver power efficiently?
It is optimized for delivering high torque at low RPMs, enabling it to generate power without excessive fuel consumption.
What design features contribute to the 4BT Cummins engine’s fuel efficiency?
The engine’s remarkable fuel efficiency is largely due to its high compression ratio and the presence of an efficient turbocharger.
What is the expected fuel efficiency of a properly tuned 4BT Cummins engine?
A well-tuned 4BT Cummins engine can achieve up to 40 miles per gallon, particularly when installed in lighter vehicles.
Why is the 4BT Cummins so fuel-efficient?
The 3.9L 4BT Cummins diesel engine has become an extremely popular platform for conversion projects throughout the past couple of years, and for good reason. Sharing virtually every internal and external piece with its big brother, the 5.9L 12V Cummins found in the 1989-98 Dodge Ram pickups, and coming as regular equipment in hundreds of commercial and industrial applications, parts availability, power potential, fuel mileage, and the lack of electronics make it an easy go-to engine when it’s time to squeeze a diesel platform into the frame rails of just about anything.
But what truly sets the 4BT Cummins apart is its impressive fuel efficiency. This engine achieves outstanding mileage thanks to its high compression ratio and efficient turbocharged design. Built for low-RPM, high-torque performance, it delivers power while conserving fuel. Many users report achieving up to 40 miles per gallon with properly tuned 4BT setups, particularly in lighter vehicles. This combination of power and efficiency ensures that the 4BT doesn’t just fit into projects—it enhances them, providing a reliable and economical solution for any diesel conversion.
What are the real-world fuel efficiency results for the 4BT Cummins?
In practical applications, many users have reported achieving up to 40 miles per gallon with well-tuned 4BT setups, particularly in lighter vehicles where the engine’s efficiency is maximized.
How does the engine achieve power without excessive fuel consumption?
The engine is designed to perform optimally at low RPMs while delivering high torque. This allows the 4BT Cummins to generate necessary power efficiently, minimizing fuel usage.
What design features make the 4BT Cummins fuel-efficient?
The fuel efficiency of the 4BT Cummins is largely attributed to its high compression ratio combined with an efficient turbocharged system. These design elements work together to enhance the engine’s overall performance without excessive fuel consumption.
What makes the 4BT Cummins unique compared to other engines?
“The 3.9L 4BT Cummins diesel engine has become an extremely popular platform for conversion projects throughout the past couple of years, and for good reason. Sharing virtually every internal and external piece with its big brother, the 5.9L 12V Cummins found in the 1989-98 Dodge Ram pickups, and coming as regular equipment in hundreds of commercial and industrial applications, parts availability, power potential, fuel mileage, and the lack of electronics make it an easy go-to engine when it’s time to squeeze a diesel platform into the frame rails of just about anything.
The 4BT Cummins isn’t just another engine—its compact size and robust design make it a standout choice for diverse applications. Enthusiasts prize it for its adaptability, as it can be seamlessly integrated into vehicles where larger engines simply won’t fit. This makes it an exceptional option for those seeking to blend power with practicality.
Consider the case of a Jeep transformed with a 4BT swap. Outfitted with off-road enhancements, this setup not only handled rugged trails but also provided a smooth ride for daily commutes. This real-world example showcases the 4BT’s unique ability to balance capability and efficiency, making it a favored choice for those who demand more from their engines.”
Why is the 4BT Cummins valued for its torque and fuel efficiency?
The engine is praised for delivering consistent torque and impressive fuel economy, making it an ideal option for those seeking a balance of power and cost-effectiveness in their vehicle builds.
What makes the 4BT Cummins a practical choice for different types of vehicles?
Its combination of durability and efficiency makes it suitable for various vehicle types, including pickups, SUVs, and specialized off-road rigs. This versatility provides users with both the power and practicality they need.
What are the benefits of the 4BT Cummins in vehicle swaps and custom builds?
The engine’s compact design allows it to fit into vehicles with tight engine bays, making it an excellent choice for custom builds. Its ruggedness and adaptability mean it can enhance both the performance and capability of a wide range of vehicles.
How does the 4BT Cummins perform in real-world applications?
The 4BT Cummins demonstrates exceptional performance in a variety of settings, from daily driving to off-road adventures. Its reliable power and versatility make it well-suited for handling diverse conditions and tasks.
Share Link