4BT Cummins 3.9L Performance Parts & Upgrades | DPP

One of the most versatile diesel engines ever created, the 4BT Cummins has earned a dedicated following among diesel enthusiasts. Compact yet powerful, the Cummins 4BT is a 3.9L, inline four-cylinder engine that’s easy to swap into vehicles with limited engine bay space. With the right upgrades, this engine delivers impressive performance and fuel efficiency, often reaching up to 40 miles per gallon—a feat for any diesel.

The 4BT Cummins engine is known for its rugged design and adaptability, which make it a favorite in various applications, from Jeeps and trucks to custom off-road rigs. At Diesel Power Products, we stock a comprehensive range of parts to help you get the most out of your 4BT Cummins, whether you're after a straightforward swap or looking to boost its power output.

4BT Cummins Specs:

The Cummins 4BT’s compact size and durability make it a popular choice for engine swaps and commercial applications alike. Here’s a quick rundown of the 4BT Cummins engine specs:

• Engine Name:Cummins B3.9L/4BT
• Applications:Chevrolet Step Vans, Commercial applications
• Configuration:Inline 4-cylinder diesel
• Displacement:3.9L, 239 cubic inches
• Bore:4.02 inches
• Stroke:4.72 inches
• Compression Ratio:17.5:1
• Aspiration:Turbocharged, non-intercooled
• Engine Weight:745 - 782 lbs
• Oil Capacity:10 quarts
• Horsepower:105 hp @ 2,300 RPM *
• Torque:265 lb-ft @ 1,600 RPM *

With a high compression ratio and turbocharging, the 4BT Cummins strikes a balance between performance and fuel efficiency. These specifications make it a reliable choice for both light-duty and custom applications.

WHAT MAKES THE 4BT CUMMINS UNIQUE?

The 4BT Cummins 3.9 has earned a reputation not only for its compact size and reliable power but also for the unique performance it brings to various vehicles. Originally designed for commercial use, this four-cylinder diesel engine found a second life in vehicle swaps and custom builds due to its versatility and impressive torque.

Enthusiasts prize the 4BT for its adaptability—it’s small enough to fit into vehicles where larger engines won’t, and rugged enough to handle challenging terrain and tough tasks. For example, one of our favorite in-house builds featured a 4BT Cummins swap in a Jeep JK. Outfitted with additional off-road enhancements, this Jeep handled everything from daily commutes to trail adventures with ease, thanks to the 4BT’s reliable torque and fuel efficiency.

From pickups to SUVs and even custom off-road rigs, the 4BT Cummins 3.9 transforms each vehicle with a blend of practicality and diesel power, providing the durability and fuel savings that make it an exceptional choice for those who need both capability and efficiency.

SHOP 4BT 3.9 CUMMINS PARTS AT DIESEL POWER PRODUCTS

Diesel Power Products offers a wide range of parts and upgrades tailored specifically for the 4BT Cummins. From tuners to cold air intakes, exhausts, and fuel systems, we have everything you need to enhance your engine’s performance and reliability. Our team of diesel experts is here to help you find the perfect parts for your build, ensuring that your 4BT Cummins performs at its best for years to come.

Disclaimer:
Diesel Power Products is not affiliated with Cummins or any of its subsidiaries or related companies. Unless a product is specifically identified as a Genuine Cummins product that has not been remanufactured, modified, or refurbished, Cummins makes no representation or warranty about the product and has not authorized, tested, or approved the parts for use in genuine Cummins brand products.

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We get a lot of calls and e-mails each day with various product, vehicle, and installation questions. Some are completely off the wall and can even catch us off guard at times, but many others are fairly routine, so we thought we'd post some of the most popular questions that can hopefully be a good resource for you.

Q: What makes the Cummins 4BT engine a good choice for swaps?
A: The Cummins 4BT engine is compact, reliable, and delivers excellent torque, making it ideal for vehicle swaps. Its relatively small size allows it to fit into vehicles with limited engine bay space, and the engine’s mechanical simplicity makes it easy to maintain. Additionally, the 4BT Cummins is known for impressive fuel efficiency and durability, making it a popular choice among enthusiasts looking for a capable yet compact diesel.

Q: Why is the 4BT Cummins so fuel-efficient?
A: The 4BT Cummins achieves impressive fuel efficiency due to its high compression ratio and efficient turbocharged design. This engine is built for low-RPM, high-torque performance, which allows it to deliver power without burning excessive fuel. Many users report achieving up to 40 miles per gallon with properly tuned 4BT setups, especially in lighter vehicles.

Q: What are common 4BT Cummins performance upgrades?
A: The Cummins 4BT engine itself shines with some modifications to the fuel system, specifically the fuel injectors and pump upgrades such as a 3200k governor spring on VE pump equipped 4PTS and a fuel pin. Beyond the engine itself, you can upgrade the turbocharger, add an intercooler, exchange the mechanical fuel pump for something like a FASS, and the list goes on.

Q: What is the life expectancy of a 4BT Cummins engine?
A: With proper maintenance, the 4BT Cummins engine is known for exceptional durability, often lasting well over 300,000 miles. This engine’s rugged build, combined with its simplicity and minimal electronics, makes it a long-lasting option for both commercial applications and custom vehicle builds. Regular oil changes, fuel filter replacements, and basic maintenance help ensure that the 4BT delivers reliable performance for years.

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