Volume 1 Issue 4 - Diesel Articles

Steve Johns loves his 1993 AM General HMC4 (4-door hardtop), powered by the stock 6.2L naturally-aspirated diesel. After years admiring the AM General H1, five years ago Steve purchased this clean specimen from his local GMC dealer for $25,000.00. It had only 50,000-miles on the odometer.

Ninety-three was only the second model year for the civilian Hummers – basically modified military trucks. (You can see the tan military paint showing through on Steve’s Hummer where the factory white paint has peeled away.) This H1 includes a 12,000-pound. Warn winch, undercarriage protection, air-conditioning, rocker-panel protection, a brush guard, tow hitch, and the Central Tire Inflation System (CTIS). This truck has every factory option offered in 1993 except power windows and door locks.

The bone stock GM V8 6.2L diesel is rated for 250 pound-feet of torque @ 2,000 RPM and 150 HP @ 3,600 RPM. Steve says in normal city driving the engine’s torque is adequate, but freeway on-ramps, passing and hills are difficult. By today’s standards, this old ‘93 is downright gutless, and Steve would like to wake-up the engine with a turbo or supercharger. Even without forced induction, Steve loves his old school 6.2L Hummer and has had zero problems with the engine while driving it to its present 76,000 miles. Steve has driven both the 6.5L turbo and 6.6L Duramax Hummers and was impressed with both. “Vastly improved,” is his take on the changes made to the newer H1 trucks. But Steve is keeping his trusty old 6.2L-powered Hummer: it’s paid for and set up the way he likes. Steve has considered an engine swap: buying a 6.5L engine would cost about $5,000.00 and a turn-key Duramax/Allison transmission conversion currently runs about $40,000.00!

Inside the H1, Steve has added a CB Radio, GPS, and an inclinometer to measure the sometimes-steep inclines he encounters. Outside, there is a Predator Motorsports roof rack, a spare-tire carrier and a rare GT products shell for the pickup bed. About 200 of these tops were built for the pickup and soft-top H1 trucks. They were built by a few manufacturers to GT’s specifications. Steve’s was made by Snug Top and sold exclusively through Hummer dealers for $3,000-5,000.00 when new.

Tires and Wheels

Light-truck tires are expensive and seem to be going up incrementally all the time. It’s common for enthusiasts to pay $250.00-$350.00 each for specialty light-truck tires, and rubber for an H1 is no exception. New Interco Swamper SSR tires in the H1 37x12.50R16.5 size are $320.00 each from mail order houses, and shipping usually isn’t free. When Steve needed two new tires he saved a bunch of money by choosing a pair of TreadWright, Inc. D-Mud retreads with Garnet Grip traction additive for the rear axle. The remanufactured TreadWrights were less than $150.00 each! The front axles rides on the standard 37x12.50R16.5 Goodyear MT tires. These tires are wrapped around factory aluminum wheels from a 2000 H1. All four tires are supported by rubber run-flats and the CTIS. The big tires and wheels on AM General H1 trucks can be difficult to balance, but Steve recently purchased a set of Centramatic continuous wheel balancers and says his H1 has never ridden so smoothly. All four tires continuously feel perfectly balanced.