Name: %title Best Chevy Silverado 6.6L LMM motor
Price: 6000 USD
Availability: InStock

The Chevy Silverado 6.6L LMM motor refers to a Duramax diesel engine used in Chevrolet Silverado HD (2500HD/3500HD) trucks during the 2007.5 to 2010 model years. Here’s a breakdown of what you should know about the Chevy Silverado 6.6L LMM motor:

Chevy Silverado 6.6L LMM motor Overview

Specification	Details
Engine Code	LMM
Displacement	6.6 liters (403 cubic inches)
Configuration	90° V8 turbocharged diesel
Fuel System	Common-rail direct injection (Bosch CP3)
Turbocharger	Variable-geometry turbo (VGT)
Block Material	Cast iron
Head Material	Aluminum
Horsepower	~365 hp @ 3,200 rpm
Torque	~660 lb-ft @ 1,600 rpm
Transmissions	6-speed Allison 1000 (automatic)

Used In:

Chevy Silverado 2500HD / 3500HD (2007.5–2010)
Also in GMC Sierra HD trucks

Key Features:

Improved emissions system (added Diesel Particulate Filter – DPF)
Retained CP3 high-pressure injection pump
Integrated exhaust gas recirculation (EGR)
No DEF (Diesel Exhaust Fluid) system yet – DEF started with the LML in 2011
Strong foundation for performance upgrades or towing

Common Mods (Aftermarket):

DPF delete & tuner (off-road only)
EGR delete
Upgraded turbo
EFI Live tuning
Cold air intake, exhaust upgrades
Common Issues to Watch For:

DPF clogging (especially if used for short trips)
EGR valve issues
Injector failure (less common in LMM than earlier LB7)
Turbo vane sticking (carbon buildup)
Fuel filter housing leak

The Chevy Silverado 6.6L LMM motor used in the 2007.5–2010 Chevy Silverado HD. Here’s a more detailed look into the key components, performance, comparison to other Duramax engines, reliability, and upgrade potential.

Detailed Technical Breakdown Of Chevy Silverado 6.6L LMM motor

Engine Internals

Block: Cast iron, deep-skirted for strength
Crankshaft: Forged steel
Connecting Rods: Forged steel, powdered metal (same as LBZ)
Pistons: Aluminum with oil cooling jets
Cylinder Heads: Aluminum, 4 valves per cylinder (32 valves total)
Compression Ratio: 16.8:1
Fuel Injection: Bosch CP3 common-rail system (25,000+ psi)
Turbo: Garrett variable-geometry turbocharger (VGT), electronically controlled
Glow Plugs: Rapid-heat system for cold starts

Emissions System Chevy Silverado 6.6L LMM motor

The Chevy Silverado 6.6L LMM motor was the first Duramax to feature the DPF (Diesel Particulate Filter):

DPF: Captures soot from the exhaust, requires periodic regeneration
EGR: Recirculates exhaust gases to reduce NOx
No DEF: Diesel Exhaust Fluid wasn’t required until the LML (2011+)
Impact: Better emissions compliance but more complexity vs. LBZ

Performance & Tuning Potential

Out of the box:

Horsepower: ~365 hp
Torque: ~660 lb-ft

With common upgrades:

Upgrade	Power Gains (approx.)
EFI Live or similar tuner	+100–150 hp
DPF/EGR delete (off-road)	+50–75 hp
Turbo upgrade	+100–300 hp (depends)
Injectors/fuel system	Up to 1,000+ hp builds

Tuning caution: Factory pistons start to become a weak point above 600–650 hp. For high-horsepower builds, forged pistons and upgraded rods are a must.

Towing & Work Capability

Max Tow Capacity (varies by configuration): ~13,000 to 16,000+ lbs
Payload: ~3,000–4,000 lbs
Transmission: Paired with the Allison 1000 6-speed auto – one of the most reliable HD truck transmissions of the time

Common Chevy Silverado 6.6L LMM motor Problems

Issue	Symptoms	Notes
DPF clogging	Power loss, regen issues	Especially in city driving
EGR valve failure	Rough idle, check engine light	Common with age
Turbo vane sticking	Lag, low boost, poor performance	Carbon buildup in VGT mechanism
Fuel filter head leaks	Hard starts, fuel in valley	Replace seals or entire filter head
Glow plug controller	Hard starts in cold weather	Sometimes causes CEL
Injector failure	Less frequent than LB7, but still possible	White smoke, rough idle, fuel in oil

Chevy Silverado 6.6L LMM motor vs. Other Duramax Engines

Engine	Years	HP/TQ	Emissions Tech	Notes
LB7	2001–2004	~300/520	None	Known for injector issues
LLY	2004.5–2005	~310/605	EGR only	Better airflow, early overheating
LBZ	2006–2007	~360/650	EGR only	Most sought-after for tuning
LMM	2007.5–2010	~365/660	EGR + DPF	Reliable, tunable, but emissions-heavy
LML	2011–2016	~397/765	EGR + DPF + DEF	Stronger, new injectors, better fuel

Recommended Mods (Daily Driver / Towing)

Tuner (EFI Live, Edge, H&S) – Even emissions-compliant tunes offer better mileage and towing performance
Transmission Tuning – Improves shift quality and clutch longevity
Cold Air Intake + Exhaust – Helps reduce EGTs, improve response
Upgraded Fuel Filter Head or Lift Pump – Protects injectors, improves startup
Monitor (Edge Insight CTS3, etc.) – Watch EGT, regen status, boost, and more

Is the Chevy Silverado 6.6L LMM motor a Good Engine?

Yes, especially for:

Heavy towing
Reliability with proper maintenance
Moderate to serious performance builds

It strikes a good balance between the older, simpler LBZ and the more emissions-heavy LML. If you’re willing to manage or modify the emissions systems (where legal), the Chevy Silverado 6.6L LMM motor can be extremely reliable and powerful.

CHEVY SILVERADO 6.6L LMM MOTOR