Once in a while, we here at Diesel Power run across something that just makes sense. When we saw Chaz Lightner's '66 Bronco, that feeling hit us. We knew the 4BT Cummins that powered the Ford had more than enough torque to propel the beast on boulders and trails yet still achieve excellent fuel economy. The fact that the swap was cleanly done-with excellent ideas and execution-was simply icing on the cake.
The idea behind this swap first started after the wicked-quick throttle response on the 520hp, 408-cid Ford V-8 that was in Chaz's Bronco led to a spin after trying to pull into traffic. He wanted something to match the torque of the 408 while being a little less temperamental. He wasn't so crazy about the 7 mpg he was averaging either, so the idea of the 4BT swap was born. Mounting of the engine itself required minor notching of the frame (for turbo clearance) but not much else in the way of custom fabrication. An NV4500 transmission was sourced and mounted behind the Cummins with little trouble.
We get questions about the 4BT from time to time, so let's talk about the engine. A call to Turbo Auto Diesel and a talk with Ken Diaz convinced Chaz that a 400hp four-cylinder would not be a problem, and Ken delivered. The Cummins in Chaz's Bronco is one of the first 4BTs we've seen that has been highly modified, so we made sure to dig as deep as we could on the details.
 This Bronco sees its fair...  This Bronco sees its fair share of off-road action, so it must be ready. Extra fuel, a high-lift jack, and CO2 bottles (to air the tires back up) are all carried onboard in case this daily-driven Bronco wanders away from its street duties. |  A Proto Fab fiberglass cowl...  A Proto Fab fiberglass cowl hood is used to clear the height of the 4BT engine and offset some of the nearly 700-pound weight of the Cummins diesel. |  The exhaust is a straightforward...  The exhaust is a straightforward and simple 4-inch turbo-back design that exits out of the body's side. |
 This is where things get interesting....  This is where things get interesting. A Cummins 4BT (basically, a Cummins 12-valve with two cylinders chopped off) was sourced out of a Wonder Bread truck. A full race build later, the engine easily tops 400 hp while getting awesome fuel economy.(continue) |  ...Believe it or not, this...  ...Believe it or not, this is the engine's fifth turbo (right). Not much was known about hot rodding the 4BT, so a lot of trial and error was needed to keep the Bronco powerful yet driveable. |  A full complement of Auto...  A full complement of Auto Meter gauges keeps tabs on the engine. A Monster Tach and a 5-inch, 160-mph speedometer keep tabs on the basics, while boost, EGT, volts, and water temperature are also monitored by smaller in-dash gauges. |