Which 6BT Cummins is Best for Your swap?
With 3 Generations from which to choose, how do you decide?
Considering the pros and cons of each generation is the clearest way to choose which 6BT Cummins is right for you.
First Generation Cummins 6BT
Initially sold with a mechanical Bosch VE injection pump, the Cummins diesel was reliable but underpowered compared to today's standards. With 160hp and 400 ft-pounds of torque, the motor was well-suited for the first RAM.
Thanks in part to the mechanical Bosch VE injection pump and mechanical timing, swapping this first-generation motor is reasonably straightforward requiring only one electrical hookup and fuel hookup. Although sluggish in stock form, when modified correctly, the 5.9 L Cummins produces over 600 horsepower.
However, when dealing with performance modifications, this motor's best advantage, simplicity, is also its biggest flaw. Without complicated fuel and timing controls, the motor sacrifices drivability as output increases. Therefore, those looking to produce big power might shy away from this first generation 5.9 L Cummins 12 valve specs. However, for those inexperienced with a Cummins swap, the first-generation motor still is a solid choice. Consumers can find these motors reasonably priced for around $2,000 US dollars.
Second Generation 6BT Cummins
An updated Cummins 6BT entered the market in 1994 and featured a Bosch P7100 pump, which allowed for more power output without sacrificing the drivability discussed earlier. As with the first generation 12-valve, the Second Generation 5.9 L Cummins also featured mechanical fueling and timing. Therefore, the motor maintained its legendary reliability and simplicity.
However, with the addition of an upgraded fuel pump, the Second Generation motor is much more accommodating to performance upgrades. For that reason, it is often considered the best bang for the buck 6BT motor.
The Second Generation motor produces 160 hp stock and 440 ft-pounds of torque. Easily tuned to 600-800 horsepower, it has enough torque for most applications. These motors are also often priced in the $2,000.00 range, making them affordable for swap applications.
Second Generation Revision
Following tightening emissions regulations, Cummins gave the Third Generation 5.9 L an electronically controlled injection pump halfway through 1998. It provided better fuel economy and tuning capabilities. However, it also added to 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 featured on these motors was still less efficient than the P7100 pump found on the updated Second Generation motors.
This choice of pump meant that the Third Generation motor could produce up to 245 horsepower and 505 ft-pounds of torque stock with tuners reaching 800 horsepower in highly modified applications. Additionally, the Third Generation 24 valve 5.9 L Cummins saw a weight increase from 975 pounds to 1,150 pounds. The added weight is sometimes a consideration when making decisions about a swap. Going for as low as $1,000 to the $5,000 range, these motors are a strong consideration for those looking to perform a Cummins conversion.
Third Generation 6BT Cummins
For enthusiasts looking to produce the most power from their Cummins swap, the Fourth Generation 24 valve 5.9 L Cummins motor is the best choice. Beginning in 2003, it features Cummins' new common rail injection system. This injection system made these motors both more complicated and capable. In stock form, these motors produce up to 350 horsepower and 640 ft-pounds of torque. However, with aftermarket support, they reach over 1,000 horsepower and nearly 2,000 ft-pounds of torque.
Because of the complicated electronics, this swap is more involved than previous generations of this motor. Even so, thanks to aftermarket support which simplifies the process, with a little patience, first-timers can complete their Cummins conversion successfully.
The Fourth Generation Cummins motor was the last 5.9 L we saw as consumers. In 2007, Cummins introduced the 6.7 L. Burdened by the addition of Exhaust Gas Recirculation (EGR) and Diesel Particulate Filters (DPF), this motor lost some of the reliability, fuel economy, and simplicity of earlier generations.
Those looking to perform a Cummins diesel conversion often stick with the 5.9 L Cummins motor found in trucks from 1989-2007 as they feature reliability, power, fuel economy, and simplicity. Arguably, they have been proven to be the best diesel motor to swap into most any application.
G Force Cummins Conversion ComponentsThe popularity of the Cummins swap is evident as enthusiasts have taken to aftermarket conversion alternatives to repower their trucks. Automotive aftermarket manufacturers like G Force offer products for a variety of engine to transmission adapter kits and other parts for your conversion project.
Transmission Adapter Kits for Ford Cummins Conversion
Both include an transmissio adapter plate and flexplate. G Force adapters allow you to position the transmission straight instead of angled like with some OEM applications. 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 your Cummins to Ford conversion kit here.
Cummins to Chevy Swap - Transmission Adapters Kits
For a Cummins to Chevy conversion, G Force offers three transmission adapter kits—the 1989-2002 Cummins to TH400/4L80E (GF-C-S), 2003-2017 Cummins to TH400/4L80E (GF-C-SL), and the 1973-1987 GM K Series Cummins Kit (GF-GMK3-Kit). Like the Ford to Cummins conversion kits, the Chevy versions include a flexplate and adapter plate.
Find out more details about our adapter kits for your Cummins to Chevy swap project here.
Transmission Adapter Kits - Cummins Allison Conversion
G Force engineered transmission adapter kits to meet the demand for Cummins Allison swaps. Our 2003-2017 Cummins to Allison (GF-A-SL) and 1989-2002 Cummins to Allison Adapter Kit (GF-A-S) were the result. Like our other Cummins transmission swap kits, the Allison versions include a transmission adapter plate and Flexplate. However, these kits also include recommended bolt kits. Get more information about our Cummins Allison conversion parts here.
G Force has even more to offer the car enthusiast that is interested in a Cummins swap. You can view our full range of products for your Cummins transmission swap to learn more.
For more about a Cummins swap, check out these blog articles—Cummins Allison| A Popular Conversion, Diesel Cummins Conversion Adapter Kits, The Popular Ford Cummins Swap, 12 Valve 5.9 Liter Cummins Specifications, and 24 Valve 5.9 Liter Cummins Specifications.
G Force has a variety of other swap kits—find out more about all of our engine to transmission adapter kits here.