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 4BTA benefits...
The Cummins 4BTA benefits from enhanced fuel delivery, intercooled intake, and turbo boost running up to 56 psi. It makes an estimated 400 hp at the flywheel, and after a careful balance-and-blueprint job by Beck Racing Engines, will turn 4,500 rpm with minimal noise and vibration.
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.
 This clean '66 is one of those...  This clean '66 is one of those 4x4s that has custom touches everywhere you look. It's a fully-streetable, highway-ready trail machine. With a four-cylinder Cummins diesel under the hood making around 400 hp at the flywheel, it has plenty of power and gets 25 mpg. |  It's generally warm year-round...  It's generally warm year-round in Phoenix, so this Bronco is air-conditioned by the breeze. The swing-away rear tire/jerry can carrier is a Proto Fab item. The frame-mounted, full roll cage is a safety system complimented by Beard seats and Simpson harnesses. |  The front radius arms that...  The front radius arms that have been lengthened by 1 foot and 3.5-inch-taller front coils are mounted with pivots under springs, so the coils can compress without bowing. At the rear, 12-leaf spring packs from Wild Horses 4x4 provide good flex without sagging. With the Rancho 9000 shocks set on "1" for the trail and the tires running 8 psi, the Bronco rides "just like a giant marshmallow," according to Chaz. The winch is a Warn XD9000i. |