1986 GMC K15 Specs

by Tim McQuade

The designation "K15" was a model number for a truck manufactured by GMC. The "K" signifies that the truck is four-wheel drive (a "C" indicated two-wheel drive). In 1986, GMC also offered the Jimmy, which used the design and components of the K15, but it was an SUV. The GMC C/K truck line has been in production since the 1960s, however, GMC phased out the "C/K" nomenclature around 2000. Today, the truck is known as the Sierra.

Engine Specifications

The standard engine on the 1986 K15 was the 90-degree, V-6 Vortec engine. The 4.3-liter engine could produce a power output of 155 horsepower at 4,000 rpm and had a max torque potential of 230 foot-pounds at 2,400 rpm. The piston compression ratio was 9.3-to-1 and the piston bore and stroke measured 4 inches by 3.48 inches. The fuel system used a four-barreled carburetor. The combined gas mileage measured approximately 15 mpg.

For added power, a 5-liter, V-8 engine design was also available. This engine was common on other GMC and Chevrolet vehicles, such as the GMC Jimmy and Suburban. This engine had a piston bore and stroke of 3.73 inches by 3.47 inches and a compression ratio of 9.2 to 1. Maximum power output of the engine was 160 horsepower at 4,400 rpm and torque output was 240 foot-pounds at 3,200 rpm. Combined gas mileage measured approximately 12 mpg.

A 6.2-liter, V-8, Detroit Diesel engine was also optional in 1986. It had a bore and stroke of 3.98 inches by 3.8 inches and a compression ratio of 21.5 to 1. It also use an overhead valve design and had two valves per cylinder, totaling 16 valves. The 6.2 diesel engine had a power output of 130 horsepower at 3,600 rpm and a torque output of 240 foot-pounds at 2,000 rpm. The engine block and head were made of cast iron and it used an indirect fuel injection system. Combined fuel economy measured 17 mpg.

Finally, a 7.4-liter, gasoline, V-8 engine was also available. This was one of the largest engines used by GMC at the time. It had a bore and stroke of 4 inches by 3.48 inches and a compression ratio of 8.3 to 1. Its total power output was 185 horsepower at 4,000 rpm and a total torque capability measured 285 foot-pounds at 2,400 rpm.


The K15 had a length of approximately 184 inches, a width of 80 inches and a height of 74 inches. The wheelbase measured 117.5 inches and the minimum ground clearance was 6.9 inches. Total vehicle weight was around 6,000 lbs.


The previous year introduced a redesigned grille, as well as a hydraulic clutch. Available transmissions were a three-speed automatic, a four-speed manual and a four-speed automatic. Three trim levels were available: the Sierra, the Sierra Grande and the Sierra Classic. The Sierra Grande featured chrome details, while the Sierra Classic had power windows and power locks.

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