The General Motors 6.2-liter Detroit Diesel engine was an early effort by the automaker to produce diesel-powered trucks and sport utility vehicles. It was a reliable, durable engine but it didn’t provide the high torque that its competitors offered on their trucks. Its lackluster performance in the ultra-heavy Hummer was particularly troublesome for owners.
GM’s 6.2-liter (379 cubic inches) diesel engine replaced the unpopular 5.7-liter Oldsmobile engine in 1982. The Olds version was GM’s attempt to deliver a fuel-efficient diesel in the wake of the 1970s oil shortages. The engine never caught on with the public. The 6.2 was a better engineered engine and a reasonable alternative to the more thirsty gasoline-powered V-8 offerings. The 6.2 was placed in Chevrolet and GMC C/K pickups and the Hummer H1. Although the engine was fairly competent, it didn’t have the pulling power, payload capacity and turbo power found in Ford trucks. The 6.2 survived until 1993 when it was replaced by the 6.5-liter diesel, according to Dieseppowermag.com and Edmunds.com.
The 6.2-liter diesel was a V-8 with a cast iron block and heads. It featured an high compression ratio of 21.5:1. Its bore diameter was 3.98 inches and the stroke was 3.80 inches. When it was introduced in 1982, horsepower was rated at 130. By the end of its life it had 143 horsepower. Torque was rated at 240 foot-pounds. Torque is the twisting force generated to give the truck or SUV towing power and acceleration. In 1993, the torque was rated at 257 foot-pounds. The engine weighed 700 lbs.
Although GM found the 6.2 to be fuel-efficient, it lacked heavy-duty strength. The pre-1993 Hummer H1s were notorious underachievers. The 6.2-powered Hummer could never break the 16-second mark in 0-60 mph testing. It was one of the slowest SUVs on the road. Weighing up to 6,000 lbs., the Hummer could only muster a 2,500-lb. payload. Fuel mileage for the pickup trucks, however, was excellent: 20 mpg in the city and 23 on the highway.
The closest competitor to GM’s 6.2 diesel was Ford’s 6.9-liter version that began production in 1978. The engine was supplied by International Harvester. It generated 170 horsepower, more than 30 more horsepower than the GM 6.2 diesel at its peak performance. GM attempted to rectify the discrepancy by developing the 6.5-liter turbo diesel in 1993. The 6.5 generated 190 horsepower and 380 foot-pounds of torque. Fuel injection wasn’t introduced until the 300-horsepower 6.6-liter Duramax debuted in 2001.
The 6.2-liter diesel is a favorite among truck restorers as a replacement engine. Vintage Chevy and GMC trucks are often modified by owners to accept the 6.2-liter diesel. Many of these engines also found their way into older Land Rovers. The 6.2’s popularity is due to its abundance, easy maintenance and low price. Junkyard 6.2 liters that originally powered the early 1980s half-ton Chevrolet C/K can be purchased for as little as $500 (in 2010).
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