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6.6L Duramax Commercial Power Options

The 6.6L Duramax diesel has been offered in several power options, identified by various RPO codes, in Kodiak and TopKick applications from 2003 to 2009. During this period, it was only offered in C4500 and C5500 medium duty models while the Isuzu 6H, marketed as the Duramax 7800 or 7.8L Duramax, and Caterpillar C7 were available in C6500, C7500, and C8500 models. These 6.6L Duramax power options are de-rated versions of the standard pickup truck engine available in the Chevrolet Silverado and GMC Sierra 2500/3500. Some of these power options also found their way into stripped chassis applications where the 6.6L Duramax diesel was available, but there is little information available regarding these instances.

6.6L Duramax RPO Codes LRY, LPD, LRX, LYE

De-rating is a common practice in medium and heavy duty commercial truck applications as customers often sacrifice performance that they do not necessarily need in favor of greater longevity and fuel economy. Additionally, each businesses needs vary and offering an engine is several power configurations could potentially give an automaker a competitive edge. In all the following instances, the engine power and torque is configured electronically by means of the ECM calibration; mechanically, the engines are based on a standard pickup version of the 6.6L Duramax diesel.

GM's offerings varied, often significantly, model year to model year. In some instances, you could purchase a Kodiak or TopKick medium duty truck with the standard pickup engine, OR you could have it de-rated by selecting one of the listing power options. For example, the LB7 was available for the 2003 - 2004 model years with or without the LRY power option. Without the LRY RPO code, the engine horsepower and torque ratings were the same as that offered in Silverado and Sierra pickup trucks. With the LRY RPO code, engine horsepower was decreased to 210 and the governed engine speed was reduced to 3,250 rpm (from approximately 3,400 rpm).

6.6L Duramax LRY Power Option

RPO Code:

LRY

Applications:

2003 - 2005 Chevrolet Kodiak C4500, C5500
2003 - 2005 GMC TopKick C4500, C5500

Engine Platform:

6.6L Duramax LB7 (through 2004)
6.6L Duramax LLY (2005)

Peak Rated Horsepower:

210 hp @ 2,750 rpm

Peak Rated Torque:

520 lb-ft @ 1,600 rpm

Governed Engine Speed:

3,250 rpm

6.6L Duramax LPD Power Option

RPO Code:

LPD

Applications:

2006 Chevrolet Kodiak C4500, C5500
2006 GMC TopKick C4500, C5500

Engine Platform:

6.6L Duramax LLY

Peak Rated Horsepower:

300 hp @ 3,000 rpm

Peak Rated Torque:

605 lb-ft @ 1,600 rpm

Governed Engine Speed:

3,450 rpm

6.6L Duramax LRX Power Option

RPO Code:

LRX

Applications:

2005 - 2009 Chevrolet Kodiak C4500, C5500
2005 - 2009 GMC TopKick C4500, C5500

Engine Platform:

6.6L Duramax LLY (through 2006)
6.6L Duramax LMM (2007+ w/ DPF)

Peak Rated Horsepower:

300 hp @ 3,000 rpm

Peak Rated Torque:

520 lb-ft @ 1,600 rpm

Governed Engine Speed:

3,450 rpm

6.6L Duramax LYE Power Option

RPO Code:

LYE

Applications:

2007 - 2009 Chevrolet Kodiak C4500, C5500
2007 - 2009 GMC TopKick C4500, C5500

Engine Platform:

6.6L Duramax LMM

Peak Rated Horsepower:

330 hp @ 3,000 rpm

Peak Rated Torque:

620 lb-ft @ 1,600 rpm

Governed Engine Speed:

3,450 rpm

Page Information

Last update: 11/20/2021

Copyright: Diesel Hub (dieselhub.com), all rights reserved

Source(s): Original spec sheets, brochures, vehicle guides, and press releases for 2003 to 2009 GMC TopKick and Chevrolet Kodiak medium duty trucks (gmfleet.com, media.gm.com, and in print form)