One of the coolest engines ever produced is the 4BT Cummins, in all of its variations. You may be wondering why we would be touting a teeny 3.9L, four cylinder engine as one of the coolest engines? Well that’s simple. This little diesel can be swapped into numerous vehicles that simply don’t have the sheer engine bay space for any of the traditional larger engines, let alone the weight. Further, the earlier mechanically controlled engines could be modified to produce impressive horsepower numbers, while still achieving over 40 miles per gallon.
In one of our in-house builds, we took a 2009 Jeep JK four door and slapped a 4BT in it, along with a host of other off road oriented upgrades and made one of the coolest JK’s on the planet (at least we think so). That Jeep took us all over the country on some of the toughest trails you can imagine, and still served as a vehicle that could easily be daily driven, turning heads everywhere it went. It’s hard to not look twice when you hear a Cummins rattling under the hood of a Jeep rolling on 40” tires!
If you’re at all familiar with the 6BT Cummins, then you’re in luck. Other than the obvious fact of one being a 6-cylinder and one being a 4-cylinder, they are extremely similar. The pistons, injectors, connecting rods, and valvetrain design are straight off of the 12v Cummins.
1.Displacement: 3.9L – 292ci 2.Cylinder Head Material: Cast Iron 3.Engine Block Material: Cast Iron 4.Compression Ratio: 17.5:1 5.Valvetrain: OHV – 2 Valves per Cylinder 6.Horsepower: 105hp 7.Torque: 265 lb-ft
One thing that really sticks out from this whole chart is the weight. The 4BT Cummins weighs about 750 lbs, which can drastically change the handling of your vehicle if you plan on swapping a 4BT in.
Diesel engines are really common in heavy duty applications. Things like semi-trucks, tractors, and large generators use diesel engines. But what about things that are sort of heavy duty, but sort of not? Something like a bread truck falls into that category, and that’s where the 4BT comes into play.
The 4BT was extremely common in step trucks, as well as other heavy-ish duty applications. Today in 2016 the 4BT has been replaced with much more efficient diesel engines, but the 4BT is still being used today.