Duramax 6.6L LMM V8
Horsepower
365 hp
Torque
660 lb-ft
Years produced
2007–2010
Aspiration
Turbocharged
- Configuration
- V8, 6.6 L
- Aspiration
- Turbocharged
- Builder
- DMAX Ltd.
- Designers
- Joint venture of GM and Isuzu (DMAX); engine blocks supplied by Fritz Winter
- Years
- 2007–2010
Offered in: Chevrolet Chevrolet Silverado 2500HD, Chevrolet Chevrolet Silverado 3500, GMC GMC Sierra 2500HD, GMC GMC Sierra 3500
The LMM added a diesel particulate filter to the Duramax to meet the 2007 emissions rules. Rated at 365 hp and 660 lb-ft, it was the only Duramax offered for the 2007 to 2010 model years and was paired with the six-speed Allison automatic. It appeared with the redesigned GMT900 Silverado and Sierra HD trucks in mid-2007. It was replaced by the LML for 2011.
What made it successful
It met the tougher emissions standards while keeping and slightly raising the LBZ's output.
Market position
Its ratings were a slight step up over its predecessor. Sourced comparisons with Ford and Ram are not yet included.
Rebuild Potential
Tier BEditorial opinion.
The LMM keeps the CP3 fuel pump and the Duramax's strong support and community while adding a particulate filter. Sources describe it as good for 300,000 miles or more when its emissions system is kept healthy. It sits at tier B because the emissions system adds cost and complexity that earlier engines lack.
Best year ranges
- 2007-2010: One design across these years; sources note it uses the more reliable CP3 injection pump and has no DEF system.
Known weak points
The first Duramax with a particulate filter; the filter and EGR system can clog with soot and carbon.
Common fix: Service or replace the EGR components and particulate filter with compliant parts.
The transmission cooler lines are a known weak spot on these trucks.
Common fix: Replace them with upgraded lines.
Common upgrade categories
- Compliant EGR and particulate filter service
- Upgraded transmission cooler lines
- Injector and fuel system service
- Cooling and gasket refresh
- Bolt-on intake and exhaust within local legal limits
This engine is emissions-equipped (EGR, particulate filter and, from 2011 on some engines, DEF/SCR). Keep the emissions equipment the truck was built with; repair or replace it with compliant parts. Removing or defeating it on a vehicle originally equipped with it is illegal under federal law. Rules vary by state (for example California/CARB), so check local law and model-year requirements before modifying.
Sources
- Duramax V8 engine (Wikipedia) (accessed 2026-09-18)
- Chevrolet Silverado HD (Wikipedia) (accessed 2026-09-18)