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Cummins 6BT Cummin Diesel Conversion transmision adapter plate and flexplate

What Do I Need to Know About a Cummins 6BT | Cummins Diesel Swap?

Discover the Basics of a Cummins Swap

A diesel Cummins conversion entails exchanging a Cummins diesel engine into another vehicle. Lots of people complete a Cummins conversion to improve the efficiency and life of their truck or car. Swapping for a Cummins might also bring a broken-down engine back to life. 

Some familiar terms surrounding these swaps include "Chummins" and "Fummins." These nicknames refer to a Cummins to Chevy swap or Cummins to Ford conversion, respectively.

At G Force, we offer a range of transmission adapter kits for a diesel Cummins conversion so that you can more easily finish your FumminsChummins, or Cummins Allison conversion projects.

Can I Swap Any Engine into Any Car?

Swapping an engine is a complicated process, particularly if you mount it into a different make vehicle. Ultimately, it depends on whether you have the materials, time, and money to accomplish your goal. If so, the possibilities are virtually endless.

Cummins Transmission Swap Components

However, there are many regulations to follow if you want the vehicle to remain street legal after the swap. Therefore, we recommend consulting with a trustworthy engineer before attempting an engine conversion. A good automotive engineer can evaluate your project and desired outcome to confirm that it will function as you intend and still remain street legal.

What is the cost of a Diesel Cummins Conversion?

Prices can vary from roughly $5,000 to $10,000 or more. It all depends on what engine you choose, what vehicle you are swapping it into, the amount of outside labor necessary to complete the project, and if you have the tools required to do the work. 

Why Complete a Diesel Cummins Swap?

Truck candidate Cummins Diesel Conversion

In recent years, engine conversions with a Cummins diesel have become increasingly common. It is one of the many ways to enhance and revive vehicles like trucks and 4-wheel-drive SUVs.

At the same time, the conversion process has also become more affordable as automotive aftermarket manufacturers have increased production of the components needed for these swaps. 

Is a Cummins Conversion worth the cost? 

Many enthusiasts say yes, and here are some of the most compelling reasons to choose a Cummins diesel engine.

Reliability and Superior Longevity

Diesel engines have proven that they easily outlast standard gasoline engines. These engines meet higher design standards because the parts which facilitate the engine's combustion cycle fall within a tight tolerance range. 
In addition, diesel fuel also offers better lubrication than gasoline. With proper maintenance, diesel engines last up to two times longer than gas-powered engines.
Furthermore, it is not unusual for a Cummins diesel engine to last up to 500,000 miles. Their longevity often means the diesel engine outlasts the vehicle itself. With a Cummins engine, owners expect their vehicle to last many years and maintain its value.

Better Performance

A Cummins diesel engine turns your vehicle into an unstoppable powerhouse. Because Cummins diesel engines deliver considerably more torque than a typical gas engine, you get faster speeds along with more towing strength. For that reason, truck owners undoubtedly get enormous value from a Cummins swap.

Easy to Modify

People experienced with car modifications who undertake a diesel engine conversion find that Cummins diesel engines easily adapt into their vehicle. New modifications and upgrade options frequently arise, which means a diesel engine can fulfill the needs of even the most hardcore hobbyists. 
Additionally, resources for Cummins engine modifications are available from numerous sources, which makes it easy to carry out upgrades as you have the time. With a Cummins conversion, you can build the powerful diesel truck you always wanted.

Improved Fuel Economy

Diesel engines are known for having much better fuel efficiency than standard gas engines. Cummins engines, in particular, offer very high fuel economy. In addition, the diesel fuel itself provides more energy than regular gasoline—adding to the fuel economy of these engines.
As a result, over time, you can save a lot of money on fuel. Who wouldn't prefer to refill their fuel tank less frequently than you would with a gas engine? Not surprisingly, over time, the money begins to add up, especially when you factor in the longevity of a Cummins engine.
Now that we've explored the reasons enthusiasts choose a Cummins. Let's delve into the well-liked 6BT, which is in widespread use. The Cummins 6BT is considered by many to be one of the most dependable engines ever made, which is why it is often chosen for an engine conversion project. 

Which 6BT Cummins Should You Consider?

To answer this question, let's take a brief look at the evolution of the Cummins 6BT.

Cummins 6BT - First Generation

Off road truck on dirt road with trees in background Cummins 6bt swap

In 1989, Dodge outsourced the manufacture of their heavy-duty truck motors to Cummins, and the 6BT was the result of the collaboration between the two companies. The 5.9 L  Cummins motor was first used in Dodge RAM trucks starting in that same year. Dodge chose to build the RAM around the Cummins 6BT in order to meet the expectations of their most demanding customers.

This version of the Cummins diesel was reliable but underpowered compared to today's standards. The engine was originally sold with a mechanical Bosch VE injection pump. However, with 400 ft-pounds of torque and 160hp, the motor was well-suited for the first RAM.

Swapping this first-generation motor is reasonably straightforward because the swap requires only one fuel and electrical hookup for the mechanical timing and the Bosch VE injection pump. Although this engine can be sluggish in stock form, it's important to remember that the 5.9 L Cummins produces over 600 horsepower when modified correctly.

However, this motor's best advantage, its simplicity, is also its biggest flaw. Because it does not have refined fuel and timing controls, this engine sacrifices drivability as output increases. Therefore, the First Generation 5.9 L Cummins 12 valve specs might not be the best choice for anyone making performance modifications to produce considerable power. At the same time, for those inexperienced with a Cummins swap, the First-Generation motor still is a solid choice. Also, these motors are reasonably priced, which also makes them an attractive alternative.

6BT Cummins - Second Generation 

In 1994, an updated Cummins 6BT entered the market. This engine showcased a Bosch P7100 pump, which supported a more powerful output without giving up the drivability mentioned regarding the First Generation of this engine. However, like the original 12-valve, the Second Generation 5.9 L Cummins featured mechanical fueling and timing. Consequently, the 6BT retained its reputation for simplicity and reliability.

At the same time, the addition of an upgraded fuel pump made performance upgrades on the Second Generation engine easier. For that reason, the Gen II is often thought to be the best value of all the 6BT motors.

With 160 hp stock and 440 ft-pounds of torque, the Second Generation motor is easily tuned to 600-800 horsepower, which is enough torque for most applications. These motors are also often priced affordably for swap applications.

Second Generation Revision

Halfway through 1998, Cummins gave the Third Generation 5.9 L an electronically controlled injection pump following tighter emissions rules. It supplied better-tuning capabilities and improved fuel economy. But, it also increased the complexity of a Cummins swap.

The new electronic fuel management made the updated second-gen motor more capable than the First Generation with the Bosch VE pump. Nevertheless, the Bosch VP44 injection pump included with these motors was still less efficient than the P7100 pump found on the updated Second Generation motors.

This selection of pump meant that the Third Generation motor could produce up to 245 horsepower and 505 ft-pounds of torque stock with tuners, in highly modified applications, reaching 800 horsepower. Furthermore, it caused a weight increase from 975 pounds to 1,150 pounds in the Third Generation 24 valve 5.9 L Cummins. The extra weight is sometimes a factor for enthusiasts making decisions about a swap. Even so, these motors merit consideration for those looking to complete a Cummins conversion.

6BT Cummins - Third Generation 

The Fourth Generation 24 valve 5.9 L Cummins motor is a fantastic option for enthusiasts looking to produce the most power from their Cummins swap. Starting in 2003, the Fourth Generation featured Cummins' new Common Rail Injection System, making these motors more capable and complicated. In stock form, these motors produce up to 640 ft-pounds of torque and 350 horsepower. Remarkably, with aftermarket support, these same motors reach nearly 2,000 ft-pounds of torque and over 1,000 horsepower.

However, complicated electronics make this Cummins swap more involved than any previous generation of this engine. Even so, with a bit of patience and aftermarket support, even first-timers can complete their Cummins conversion successfully. 

Unfortunately, for consumers, the Fourth Generation Cummins engine was the last 5.9 L available. In 2007, Cummins launched the 6.7 L. However, hampered by the addition of Diesel Particulate Filters (DPF) and Exhaust Gas Recirculation (EGR), this engine lost fuel economy, reliability, and simplicity compared to earlier generations.

That is why those performing a Cummins diesel conversion often stick with the 5.9 L Cummins motor found in trucks from 1989-2007. These trucks tend to be more reliable, robust, and fuel-efficient. Arguably, they have proven themselves to be the best diesel motor for most swap applications. 

G Force has engineered a series of transmission adapter kits for the most popular Ford, Allison, and Chevy transmission to a Cummins engine. Let's take a deeper look at each option. 


Enjoy a Better Ride with a Ford Cummins Swap

As the challenges with the 6.0 Ford Powerstroke engine became well known over time, many automotive experts felt that most of these concerns traced back to the initial design. Although many drivers appreciate the luxurious interior of a Ford truck, often the engines were not as highly regarded. This inconsistency made the Ford Cummins swap a popular solution over the years.

Common Concerns with the 6.0 Ford Powerstroke Engine:

  • The 6.0 head studs, which did not have enough clamping force and caused blown head gaskets
  • The factory EGR system for emissions standard compliance
  • HPOP failure
  • Oil coolers clogging
  • FICM failure
  • Injector stiction
red truck cummins conversion

Even though 6.0 is often considered the "problem child," the upgrades made to the 6.4 did not deliver adequate improvement. In the 6.4 L, the fuel system had corrosion issues, turbo pipes cracked, and there were oiling issues. Plus, the EGR system still needed improvement. For these reasons, a lot of people chose to swap a Cummins into their Ford truck. 

A Ford Cummins Swap is an outstanding choice for those who want the reliability of a Cummins engine with the loaded interiors of Ford trucks. Cummins engines are simple yet powerful. Plus, they remain reasonably priced. These are a few reasons why a Fummins swap/Ford Cummins conversion is an ideal diesel conversion for Ford trucks.

Ford Cummins Aftermarket

Because of its popularity, Cummins Conversion components are a thriving aftermarket. The following parts make a Fummins Swap possible:

  • Transmission adapter kits, which include transmission adapter plate and flexplate
  • Swap kits
  • Exhaust systems
  • Fuel components
  • Cooling system components
  • Motor mounts
  • Wiring
  • Sensors

Ford Cummins Swap Compatibility

The least complex of the group is the 12 valve Cummins. It was introduced in 1989. In 1998, the 24 valve Cummins came along. It is more powerful but has more complicated electronics. Next in line, the Commonrail Cummins came out in 2003 and was engineered with a high-pressure fuel rail. 

Cummins Swap Transmission Adapter Kits from G Force are available to adapt a Ford 5r110 automatic transmission, Allison 1000, and early Chevy transmissions to a Cummins engine. Any of these engines are stellar candidates for a Ford Cummins swap. However, a Ford Cummins conversion kit makes any of these swaps easier. The 6.0 Ford truck is the most popular for a conversion. However, enthusiasts have completed Fummins swaps in 7.3 and 6.4 trucks as well.

Transmission Adapter Kits Make Things Easier

Without a transmission adapter kit to mount a Cummins to a Ford, Chevy, or Allison transmission, a Cummins Conversion is more challenging. In addition, motor mounts and other swap components make a swap straightforward. G Force offers two transmission adapter kits for the Ford 5R110. These kits might seem unnecessary at first, but they reduce frustration and save so much time, in the long run, they've become indispensable.

5R110 Transmission Adapter Kit for Ford Cummins Swap 

G Force kits come with a flexplate and an adapter plate. The GF-F5R110-SL shown here also comes with mounting hardware. Instead of angled like some OEM applications, G Force adapters allow you to position the transmission straight. Both kits also require a Ford Powerstroke starter. The 6.4 L starter is recommended. However, the Ford 6.0L Powerstroke starter is an option, although, with it, some bellhousings need additional interior clearance. See the details for your Cummins to Ford conversion kit here.


Adaptability is a pivotal element to Cummins Allison Combination

Specific transmission and engine combinations produce better results compared to others. It all depends on what you want from your swap. Whether you sled pull, tow, race, or you simply want a smoother ride; a Cummins swap is an excellent choice.

The Allison 1000 Series is no longer limited to Duramax pickup truck engines. This engine series effortlessly handles the torque of a Cummins engine. In addition, in conjunction with your choice of transmission controller, an Allison 1000 Series lets you adjust your transmission performance to your driving preferences and improve your on-road or track experience.

A Bit of History

1999 Allison 1000 5-speed Series became available. A few years later, in 2001, GM was the first large automaker to convert from a manual to an automatic transmission for diesel engines. They exchanged the 4L80E transmission with the Allison and combined it with their 6.6 L Duramax diesel engine. The adaptability, size, and power of the 1000 Series exceeded anything GM competitors had on the market at that time.

Because manual transmissions fundamentally are simpler designs, there is no communication between powertrain components. Therefore, the multifaceted automatic Allison 1000 offered enhanced elements like engine braking and dynamic shift schedules.

For these reasons, the attractiveness of an Allison Cummins conversion grew along with its status. The swap became known as an innovative use of technology. At the same time, its reliability and strength made it one of the most coveted automatic transmissions in its class.

From 2001 – 2005, the Allison 5-speed transmission rolled off the line in the GMC Sierra and Chevy Silverado 2500/3500 with 6.6 L Duramax diesel engines. Beginning in 2006, GM switched these trucks to the Allison automatic 6-speed. This sixth gear made the transmission a double overdrive. The effect was to lower cruising RPMs by about 14%, resulting in better fuel efficiency and speed. To date, GM continues production with this engine-transmission pairing.

The flexibility and of the Allison 1000 Series continue to gain popularity and is one of the most popular Cummins Allison conversion today.

What a Cummins Diesel Adds to Your Vehicle

  • Performance—compared to the traditional gasoline-powered engine, a diesel engine provides considerably more torque resulting in superior acceleration and more towing capability.
  • Engine longevity—it is not unusual for a Cummins diesel engine to last longer than the vehicle itself.
  • Improved fuel economy—diesel engines are rated for higher fuel efficiency than gasoline engines.
  • Straightforward modification—new upgrades and modifications frequently become available for diesel engines. Also, an abundance of resources are readily available to assist do-it-yourselfers.

When paired with an Allison, the Cummins Diesel becomes an unbeatable combination. It has become a popular choice among owners of Dodge trucks.

Allison 1000 Ratios

*6th gear available in model years 2006 and newer.

Other Allison Specs

Get High Horsepower From Your diesel Cummins Allison Swap

If you want a transmission to support your high horsepower Cummins, a Cummins conversion might be the answer. G Force Performance Products offers two Cummins Allison Conversion Adapter Kits. The one you choose depends on the year of your engine. 

1989-2002 Cummins Allison Conversion Adapter Kit

Our 1989-2002 Cummins Swap Kit includes a bellhousing adapter plate, Cummins Allison Transmission Adapter Kitsflexplate, and mounting bolts. It is designed to bolt an Allison 1000 automatic transmission for model years 2001 – 2007 or with the LT Duramax bellhousing pattern to a 6BT Cummins engine.

Details of note about this engine to transmission adapter kit-

  • Engine Years: 89-02
  • Transmissions: Allison 1000 Series automatic
  • G Force Performance adapters position the transmission straight, not angle rotated, as in some OEM applications.
  • Our adapter kit requires the use of a Ford 6.4 L Powerstroke starter.
  • As an option, a Ford 6.0 L Powerstroke starter can be used, but some bellhousings will require additional interior clearance.
  • In some applications, clearance modifications to the engine block pan rail and the Powerstroke starter may be necessary.

2003 – 2017 Cummins Allison Adapter Kit

The G Force 2003 – 2017 Cummins to Allison Adapter Kit includes a bellhousing adapter plate, flexplate, and mounting hardware. It is also designed to bolt a Cummins 6BT engine to an Allison 1000 Series automatic transmission for the years 2001 – 2007 or with the LT Duramax bellhousing pattern.

Other important information about the 03-17 Cummins engine to transmission adapter kit.

  • Engine Years: 03-17
  • Transmissions: Allison 1000 Series automatic
  • Unlike some OEM applications, the G Force adapter plate positions the transmission straight, not angle rotated.
  • A Ford 6.4 L Powerstroke starter is required by this adapter kit.
  • Optionally, with additional interior clearance for some bellhousings, a Ford 6.0 L Powerstroke starter can be used.
  • Clearance modifications to the Powerstroke starter and engine block pan rail may be necessary for some applications.

Many advantages come with an Allison Cummins swap. Our experts on transmission adapters are available to answer your questions and help guide you through the process.

Cummins to Chevy swap Transmission Adapter Kits

For a Cummins to Chevy swap, G Force offers three swap adapter kits—the 1973-1987 GM K Series Cummins Kit (GF-GMK3-Kit)1989-2002 Cummins to TH400/4L80E (GF-C-S), and the 2003-2017 Cummins to TH400/4L80E (GF-C-SL)

Cummins to Chevy Transmission Adapter Kits

Similar to the Ford to Cummins conversion kits, the Chevy versions include a flexplate and adapter plate. However, the K Series kit also comes with a Cummins 6BT to Chevy Drop CrossmemberMotor Mount, and bolt kits for the adapter, flexplate, and starter. You can find out more details about our adapter kits for your Cummins to Chevy swap project here.

If you plan to swap your K-series Chevy truck with a Cummins engine, our GF-GMK3-KIT will streamline the process. This kit includes an adapter plate and flywheel to bolt your Cummins to a Chevy transmission such as TH400 or 4l80e, motor mounts to bolt the engine in your K-series, and a drop engine crossmember to provide clearance for the large oil pan on the Cummins. It also includes the necessary bolt kits to simplify your install.

G Force has even more to offer the car enthusiast that is interested in a Cummins swap. Please review our complete range of products for your Cummins swap to discover more.

We want to know all about your next project, #swappedmyride. Find us on Facebook or Instagram @gforceperformanceproducts.

For more about a Cummins conversion, check out these blog articles—

G Force has other swap kits—see all our engine to transmission adapter kits and components here.


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