photographer: David Kennedy, Courtesy of General Motors Corp.
Life for the 6.5L continues beyond General Motors' creation of the Duramax. In its final GM version, the 6.5L made 215 hp and 440 lb-ft of torque with a rear-mounted turbocharger. Over the next year, we're going to see if those numbers can be pushed up into Duramax territory without giving up simplicity or reliability.
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.
While no one would ever confuse the Duramax for the 6.5L, you can certainly see the family resemblance between the two. The cylinder bore (4.06-inch) is the same, the oil filler tube is in the same location, the A/C compressor and power-steering pump are still on the driver side of the engine, and even the engine's main electrical connectors are carried over from the 6.5L.
| GENERAL MOTORS DIESEL ENGINE SPECIFICATIONS |
| | 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 |