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GM Diesel Truck Engine Swap - Project 6.5L

Part 1: The Makings Of The Perfect Engine Swap

Photography by Courtesy of General Motors Corp.,

General Motors has always enjoyed an impressive array of engines in its powertrain collection. With few exceptions, no matter what you thought of the rest of the vehicle, the powerplant under the hood of a Chevy or GMC truck has always been able to compete with the best anyone had to offer. Except, as some of you will now point out, its first attempt at a light-duty diesel engine: the 6.2L V-8.

Originally designed with the help of Detroit Diesel (which, at the time, was still part of GM), the 6.2L and, later, the 6.5L engines weren't intended to be the powerhouses one might expect from GM. Keep in mind that when these engines were originally conceived in the late 1970s, fuel economy was all the rage. The 6.2L diesel hit the market as a high-mpg alternative to the V-8 gas engine lineup at a time when 130 hp wasn't all that bad.

Rather than try to convince you the 6.2 and 6.5L diesels are better than you remember (we just might do that too), we're going to lay out the case for why the modern 6.5L is an ideal diesel-engine swap candidate for any vehicle that you want diesel powered. Or, as in the case with our '82 K5 Blazer, re-powered. In this first of many installments, we'll reintroduce you to the Duramax's older brother and compare the 6.5L to some of the other diesels people talk about swapping.

  6.2L vs. 6.5L vs. 6.6L Duramax
Engine codes: LH6, LL4 L56, L57,L65 LB7, LLY, LBZ, LMM
Year introduced: 1982 1992 2001
Displacement: 379 ci 397 ci 403 ci
Bore x stroke (in.): 3.98 x 3.80 4.06 x 3.82 4.06 x 3.90
Block material: cast iron cast iron cast iron
Head material: cast iron cast iron cast aluminum
Aspiration: normal turbo fixed or variable turbo
Valvetrain: OHV 2-V OHV 2-V OHV 4-V
Compression ratio: 21.5:1 18.0-20.2:1 17.5-16.4:1
Fuel injection: indirect indirect direct-injection, high-pressure common rail
Horsepower (intro): 130 hp @ 3,600 rpm 190 hp @ 3,400 rpm 300 hp @ 3,100 rpm
Torque (intro): 240 lb-ft @ 2,000 rpm 380 lb-ft @ 1,700 rpm 520 lb-ft @ 1,800 rpm
Horsepower (max): 143 hp @ 3,600 rpm 215 hp @ 3,200 rpm 365 hp @ 3,200 rpm
Torque (max): 257 lb-ft @ 2,000 rpm 440 lb-ft @ 1,800 rpm 660 lb-ft @ 1,600 rpm
Max rpm: 3,600 rpm 3,400 rpm 3,450 rpm
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