6.6 L Duramax LLY
The Duramax LLY was introduced in 2004 to replace the popular LB7. Like the LB7, the LLY utilizes a high pressure common rail direct injection system. The LLY was General Motors' first attemp at implementing emission controls on a diesel engine to meet stricter emissions requirements in the furture. The LLY adopted a variable geometry turbocharger (VGT) and exhaust gas recirculation (EGR) system to help reduce emissions. Huge changes to the LLY debuted in 2006, but the engines were mechanically identical. LLY's were used in the Hummer H1, Chevrolet Silverado HD, and GMC Sierra HD.
6.6 L LLY Specifications:
Configuration: |
90 degree V8 |
Displacement: |
403 cubic inches, 6.6 liters |
| Block/head material: | - Cast iron block - Aluminum cylinder heads |
Compression Ratio: |
17.5:1 (16.8:1 in 2006) |
Bore: |
4.06 inches |
Stroke: |
3.90 inches |
Aspiration: |
- Garrett variable geometry turbocharger (VGT) - air to air intercooler. |
Valvetrain: |
OHV, 4 valves per cylinder |
| Injection: | - Direct injection - High pressure Bosch common rail, CP3 injection pump - 23,000 psi max injection pressure |
Oil Capacity: |
10 quarts w/filter |
Weight: |
approx. 835 lbs |
| *Horsepower: | - 310 hp @ 3,000 RPM - 320 hp @ 3,000 RPM (2006) |
*Torque: |
520 lb-ft @ 1,600 RPM 560 lb-ft @ 1,600 RPM (2006) |
| Maximum Engine Speed: | 3,250 RPM |
| Emissions Controls: | - Exhaust gas recirculation (EGR) - Variable geometry turbocharger (VGT) - Catalytic converter |
*output varies slightly with model year.
2006 LLY Changes:
On a mechanical level, the 2006 LLY was nearly identical to the previous version, however the following changes were made to the 2006 version:
- Main bearing upgraded for longevity.
- Compression lowered to 16.8:1.
- Thicker connecting rods.
- Revised cylinder heads to match lowered compression ratio.
- Fuel injection pressure raised to 26,000 psi from 23,000 psi.
- New fuel injector design.
- New variable geometry turbocharger for cleaner emissions & better throttle response.
- Larger EGR cooler installed.
6.6 L LLY Features & Info:
- LLY applications include the Chevrolet Silverado HD, Hummer H1, GMC Sierra HD, Chevrolet Kodiak, GMC Topkick.
- First Duramax to feature emissions controls.
- 4 bolt mains, forged & fractured connecting rods.
- Aluminum pistons with piston cooling oil jets.