Diesel Explorer: Introduction

June 23, 2013 | 1 Minute Read

I first became interested in diesel engines after learning about the diesel cycle in a thermodynamics class. This led to my first diesel engine swap—a 3.9 L Cummins 4BT into a heavily modified Ford Ranger. I boxed the frame, installed 1-ton axles, air lockers; everything to make a really great off-road machine that still managed an MPG somewhere in the 20s. It was cool, but not exactly what I wanted since it was a bit impractical, and the stiff frame made the truck vibrate too much on the highway. I took it all apart, sold the valuable parts, and scrapped the rest. My diesel project was gone, but my interest in diesels was not. I decided I wanted a practical diesel SUV that got good mileage—nothing spectacular, just a good solid vehicle. This time, I would take what I had learned from that and my previous projects, but think long and hard about the goals of the project before starting.

At this point in time—around 2007–2008—I believe the only commercially available (in the US) diesel SUVs were the Jeep Liberty and the way-out-of-my-price-range Volkswagen Toureg, neither of which got the mileage I was looking for. I could have went for a Volkswagen TDI Golf, but I really like having 4 wheel drive for snow and mildly muddy roads/trails.

Being a Cummins enthusiast, I used to visit the forums at, where I stumbled upon an inspiring thread by forum member TDIwyse. He had acquired a 3.3 L Cummins turbo diesel engine and put it in a Jeep YJ. The swap alone looked really clean and done quite well, but the part I was most interested in was the mileage. He claimed he was getting MPGs in the 30s. I decided my project would be built around that engine—a Cummins B3.3.