• The 6.5L diesel was replaced by the Duramax 6600 at 6.6L.motor image by Petr Efremov from Fotolia.com
  
  General Motors introduced the 6.5L diesel engine in 1992 as a replacement for their 6.2L engine. The engines were manufactured by Detroit Diesel, and were designed for fuel efficiency rather than power. The engine was offered in both naturally aspirated and turbocharged models. Typically, the engine was a cast iron block with cast iron heads that made up the 395-cubic-inch body. The bore was 4.06 inches, with a stroke of 3.82. The maximum engine speed was 3,400 rpm.
  
  

Optimizer 6500

• The GM Optimizer 6500 is a turbo-charged, 6.5L diesel long block engine. These were manufactured from 1992 until 2009. This model came in both a naturally aspirated (N.A.) diesel, using air for combustion, and a mechanical fuel injection turbo. The fuel injection Optimizer 6500 had a peak horsepower ranging from 190 to 205 hp at 3,200 rpm, or revolutions per minute. The N.A. model produced between 160 and 170 horsepower at 1,800 rpm.
  
  

6.5L Turbo Diesel Drop In (CK)

• Manufactured from 1996 until 2002, the 6.5L Turbo Diesel Drop In was a V-8 engine that had an indirect electronic fuel injection, meaning that the fuel would not be injected directly in the combustion chamber. This is usually a feature of gasoline engines, but this particular engine was able to use a smaller diesel due to this design. Nevertheless, the horsepower produced by this diesel was 215 hp at 3,400 rpm. At 2,600 rpm, the horsepower of the 6.5L Turbo Diesel Drop In was 195 hp.
  
  

6.5L Long Block Supreme

• Manufactured between 1997 and 2002, this 6.5L Long Block Supreme diesel engine featured a new block, camshaft and cylinder heads with electronic injection pumps for turbocharged power. This indirect electronic fuel injection system produced a horsepower of 195 at 3,400 rpm.