Orange You Glad It's A Diesel?
Everything, it seems, in Chaz Lightner's life is orange and black. That includes his T-shirt, his business card, and his '66 Bronco, which makes black smoke when he gets on the throttle. Color aside, the Bronco is many things rolled into one — solidly built trail machine, daily driver, fuel-efficient commuter, and turbocharged, intercooled, high-torque stoplight-to-stoplight surpriser. But most of all, it's a unique 20-year-long engineering project, a rare 4x4 combined with a rare engine, the 4BTCummins diesel.
Chaz has long had racing in his blood, so this particular Bronco has a history, having been fitted with a number of high-performance gas engines, including a Can Am Ford 408ci V8 built to the tune of 520 hp. Radical turbocharging provided huge horsepower numbers, but turned out to be somewhat less driveable than Chaz had in mind, so he came up with the idea of using a Cummins diesel to provide big torque in a more progressive, efficient manner. The more familiar 5.9L Cummins B6, used in Dodge Ram pickups among other things, is a long son-of-a-gun - practically impossible to fit under the hood of an early Bronco. And it's heavy - too much for most front springs - and nothing lightweight can live behind it for long.
The Cummins 4BT four-cylinder, the baby brother to the 6BT, isn't exactly light either, but it would prove to be feasible to swap. From the factory, the 4BT is usually rated at 105 hp and 265 lb-ft of torque, but they can be built to much higher specs. With a simple turn of the screwdriver, a 4BT can make over 160 hp, and over 400 lb-ft of torque. With more fuel, a turbo and intercooler….the sky's the limit. Plus, while the motors are somewhat scarce, a 4BT still costs much less than a 6BT and many can be found languishing in late 1980s bread vans, which were converted to diesel by Cummins in the mid 1980s. The aged vans, engine and all, can often be had for under $3,000.
To recondition the engine, Chaz went to Beck Racing Engines in Phoenix, Arizona, where it was rebuilt, balanced, and blueprinted to keep noise and vibration to a minimum. Since the engine would be operating under heavy boost, the head was fire-ringed and the head bolts were replaced with 14mm ARP studs. The fuel delivery system was upgraded by combining a lift pump from a 12-valve Cummins and a four-cylinder P7100 pump. It was designed by Ken Diaz at Turbo Auto Diesel, who also added 125 hp Cummins injectors.
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