What is the difference in the two? Actually what are the different bore sizes for all generations?

 

LG5 - Commercial Grade inline 6 cylinder

Specifications
Engine description: 7.8L I6 Turbodiesel; 6H
Displacement: 7.8L / 475.9 in³
Bore and stroke: 4.53 / 4.92 (in.)
Block / Head: Cast iron / Cast aluminum
Aspiration: Turbocharged & Intercooled
Valvetrain: OHC 4-V
Compression: 16.0:1
Injection: Direct; Denso Common-rail
Power / Torque: 200 hp (150 kW) @ 2,200 rpm / 520 lb·ft (705 N·m) @ 1,450 rpm (Standard)
Power / Torque: 275 hp (205 kW) @ 2,200 rpm / 860 lb·ft (1,166 N·m) @ 1,450 rpm (High-Torque Version)

LB7

The LB7 was the first to be introduced in 2001. The V8 engine is a 6.6 L (~403 CID) and it has 300 hp (224 kW) and 520 lb·ft (705 N·m) of torque. It is a 32-valve design with high-pressure common-rail direct injection and aluminum cylinder heads.

The Duramax was on the Ward's 10 Best Engines list in 2001 and 2002.

The following trucks use the LB7:

Chevrolet Kodiak/GMC Topkick
Chevrolet Silverado/GMC Sierra HD

Specifications
Engine Description: LB7
Displacement: 6.6L / 403 in³
Bore x Stroke: 4.06 in (103 mm) x 3.90 in (99 mm)
Block / Head: Cast gray iron / Cast aluminum
Aspiration: Turbocharged & Intercooled
Valvetrain: OHV 4-V
Compression: 17.5:1
Injection: Direct; Bosch High Pressure Common-rail
Power / Torque: 300 hp (220 kW) @ 3,100 rpm / 520 lb·ft (705 N·m) @ 1,800 rpm


LLY

The LLY (internally called the 8GF1) is a 6.6 L (6599 cc) turbocharged engine which debuted in 2004 in GM trucks. It is a 32-valve design with high-pressure common-rail direct injection and aluminum cylinder heads. Output is 310 hp (231 kW) at 3100 rpm and 605 lb·ft (820 N·m) at just 1800 rpm. The engine was released with a new Garrett turbocharger with a variable geometry vane system. The valve covers were scalloped to allow access to the injectors without having to remove the valve covers, saving significant labor costs if injector replacement became necessary, and preventing leaked fuel from entering the crankcase, causing oil dilution.

The following trucks used the LLY engine:

2006 Hummer H1 Alpha

Specifications
Engine Code: LLY
Displacement: 6.6L / 403 in³
Bore x Stroke: 4.06 in (103 mm) x 3.90 in (99 mm)
Block / Head: Cast gray iron / Cast aluminum
Aspiration: Turbocharged & Intercooled
Valvetrain: OHV 4-V
Compression: 17.5:1
Injection: Direct; Bosch High Pressure Common-rail
Power / Torque: 310 hp (231 kW) @ 3,000 rpm / 605 lb·ft (820 N·m) @ 1,800 rpm


LBZ

The LBZ is nearly identical to the LLY engine. It is a 6.6 L turbocharged engine and was introduced in 2005 for the 2006 and early 2007 model years. Its output is 360 hp (268 kW) at 3200 rpm and torque is 650 lb·ft (881 N·m) at 1600 rpm. It's mated to a new Allison 1000 6-speed transmission.

The following trucks have or are due to have the LBZ engine:

Chevrolet Silverado HD
Chevrolet Kodiak
GMC Sierra HD
GMC TopKick
2006 Hummer H1 Alpha
Chevy Express full-size
GMC Savana full-size

Specifications
Engine Code: LBZ
Displacement: 6.6L / 403 in³
Bore x Stroke: 4.06 in (103 mm) x 3.90 in (99 mm)
Block / Head: Cast gray iron / Cast aluminum
Aspiration: Turbocharged & Intercooled
Valvetrain: OHV 4-V
Compression: 16.8:1
Injection: Direct; Bosch High Pressure Common-rail
Power / Torque: 360 hp (268 kW) @ 3,200 rpm / 650 lb·ft (881 N·m) @ 1,600 rpm


LMM

The LMM specifications are nearly identical to the LBZ engine. It is a 6.6 L turbocharged engine and was introduced in 2006 for the 2007.5 model year. Its output has seen a slight increase of 5 hp (4 kW) and 10 lb·ft (14 N·m) of torque over the LBZ. This makes it 365 hp (272 kW) at 3200 rpm and 660 ft (201 m)·ft·lbf of torque at 1600 rpm. It's mated to an Allison 1000 6-speed transmission.

The LMM Duramax 6.6L V-8 has new equipment to help it meet the US EPA mandated 2007 emission standards. The new standard requires a 90-percent reduction in particulate matter (PM), compared with the previous standard, implemented in 2004, and a 50-percent reduction in oxides of nitrogen (NOx). The use of reformulated, ultra-low sulfur diesel fuel, which went on sale nationwide in the fall of 2006, is required to meet the new emissions standard and prevent damage to the emissions equipment.


Specifications
Engine Description: LMM
Displacement: 6.6L / 403 in³
Bore x Stroke: 4.06 in (103 mm) x 3.90 in (99 mm)
Block / Head: Cast gray iron / Cast aluminum
Aspiration: Turbocharged & Intercooled
Valvetrain: OHV 4-V
Compression: 16.8:1
Injection: Direct; Bosch High Pressure Common Rail with CP3.3 Injection Pump
Power / Torque: 365 hp (272 kW) @ 3,200 rpm / 660 lb·ft (895 N·m) @ 1,600 rpm
To meet the new emissions regulation in the US, the LMM Duramax 6.6 L V-8 engine features:

Additional combustion control, including an even more efficient variable-geometry turbocharging system, cooled (enhanced) exhaust gas recirculation (EGR) and closed crankcase ventilation to reduce nitrogen oxides (NOx)
Additional exhaust control, including oxidizing catalyst and new diesel particulate filter (DPF) to reduce soot and particulate matter
Increased-capacity cooling system
New engine control software
Use of low-ash engine oil (CJ-4)
The following trucks have or are due to have the LMM engine:

Chevrolet Silverado HD
GMC Sierra HD
Chevrolet Kodiak
GMC Topkick
Chevrolet Express/GMC Savanah



Hope that helps Bud..

 

Excellent info.

Thanks, bud.

 

no problem.. glad I could help