Cummins 4BTA3.9-G2 Diesel Engine for Generator Set
4 Cylinders, in Line
Turbocharged & Intercooled
24V, Electric Start
Direct Injection Pump
The off-roading community has taken quite a liking to the Cummins 4BT engine; known primarily as 4BT . The engine won’t win any races as the maximum horsepower is only 105 hp at 2,300 rpm however the engine is extremely popular when it comes to the torque ratio. The standard 4BT will produce 265 lb-ft of torque at 1,600 rpm however common upgrades can increase the torque ratio to well over 750 lb-ft of torque. That is a lot of torque at the wheels; perfect for traversing steep inclines or hugging the edge of a trail. There is a whole community over at 4BT that focuses on all the info you will ever need to swap a diesel engine into a off-road vehicle.
Cummins 4BT engines are also easy to maintain, simple in design and can get upwards of 30-40 mpg with performance upgrades. The 4BT is the most popular diesel engine swap for off-roading because it is simple to upgrade the turbo, camshaft, injectors and fuel pumps in addition to being the biggest diesel engine that will easily fit into a Jeep or 4Runner. A Cummins 6BT will simply be too large.