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) |
| Horsepower | 210 hp @ 2,750 rpm |
| 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 |
| Horsepower | 300 hp @ 3,000 rpm |
| 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) |
| Horsepower | 300 hp @ 3,000 rpm |
| 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 |
| Horsepower | 330 hp @ 3,000 rpm |
| Torque | 620 lb-ft @ 1,600 rpm |
| Governed Engine Speed | 3,450 rpm |