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|12-28-2008, 11:23 AM||#1|
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"Duramax 6600" 6.6L V8 (LB7) Turbo Diesel Features & Benefits
"Duramax 6600" 6.6L V8 (LB7) Turbo Diesel Features & Benefits
The 6.6-liter 90-degree turbo diesel LB7 V8 is new from the crankshaft up. Called the Duramax 6600, this diesel brings class-leading output, exclusive durability enhancing features and superior noise, vibration control to heavy-duty GMC Sierra pickups. The LB7 combines Powertrain's industry-leading expertise in engine management with the commercial diesel know-how of Isuzu Motors.
NEW OR CHANGED FOR 2001 MODEL YEAR
DEEP-SKIRTED BLOCK WITH INDUCTION HARDENED BORES
The foundation for the Duramax 6600 diesel's superior performance is its cast-iron engine block. The block was developed using computer-based Finite Element Analysis, which optimized its balance of strength and weight.
Exceptional rigidity provides the basis for smooth, low-noise operation. Only 34.88 inches in length, the 6600 block is 1.18 inches shorter than the 6.5-liter L65 diesel block, and lighter and more compact than competitive engines from Dodge and Ford. That translates to better fuel mileage and greater flexibility in vehicle design.
The Duramax also features induction hardened cylinder bores--a technique borrowed from larger diesel engines and exclusive in the pickup class. The cylinders are polished, heat-treated with electrical induction coils and then polished again. The process creates cylinder walls that are resistant to wear, without the weight or production cost of pressed-in liners.
The main bearing caps have four bolts, but not the conventional all-vertical type.
Each cap is cross drilled, with two bolts installed vertically and two horizontally. This heavy-duty feature increases overall rigidity, and reduces noise and vibration compared to the L65 diesel.
CAST ALUMINUM LOWER CRANKCASE AND BELL HOUSING
A die-cast aluminum lower crankcase strengthens the engine block and serves as the lower engine cover, keeping weight to a minimum. The aluminum bell housing bolts to both the block and lower crankcase, providing full-circle attachment for the transmission and stiffening the entire driveline.
This cross-attachment of major castings works in effect like a single engine casting. That means superior vibration control. Yet extensive use of aluminum, including the bell housing, lower crankcase and cylinder heads, and the optimized block design, make the Duramax 6600 the lightest engine in its class. It weighs just 835.5 lbs fully trimmed, compared to 930 lbs for Ford's 7.3-liter diesel V8 and 963 lbs for Dodge's 5.9-liter line six.
The forged steel crankshaft is surface-hardened by nitriding--a process widely viewed as the most effective means of limiting wear and ensuring durability. After forging, the entire crank is machined and then coated with liquid nitrogen. The result is a hard, virtually distortion-free surface. The crank was also designed to reduce weight. In place of a conventional disc-type flywheel, the Duramax flywheel has its own counterweights. That ensures excellent rotational balance, yet moves weight from the crankshaft inside the engine block to the flywheel outside it.
OIL SPRAY PISTONS
Aluminum pistons minimize reciprocating mass and improve efficiency. They are designed with a slightly barrel-shaped profile (almost imperceptible to the naked eye) that limits scoring and scuffing of the cylinder walls. Yet the key to long-term durability is proper cooling, and the 6600 goes to great lengths to limit the effect of high temperature and combustion pressure on the pistons.
Like many medium-duty diesel engines, the Duramax has small jets near the bottom of the cylinder walls that spray cooling oil under the piston skirt as the piston moves up and down. Yet this diesel goes a step further. Typical oil-spray systems shoot oil under the pistons in a largely random pattern. Each Duramax piston has a small hole cast in its skirt.
As the pistons move up and down the hole passes over the spray jet. When the hole and jet align, oil is forced through the piston skirt and into a channel cast inside the piston. The oil travels up toward the rings and the bottom of the piston bowl, where most heat is generated, rather than collecting around the lower portion of the skirt.
FRACTURED CONNECTING RODS
Each connecting rod is hot-forged as one piece, then broken across the crank bearing journal prior to assembly with a sharp, fracturing blow. This metallurgical technique gives each rod and cap its own unique, uneven mating surface. When bolted together, the two pieces mate precisely. The fractured surface keeps the rod and cap from sliding in any direction, greatly reducing the potential for adverse bearing wear.
FOUR-VALVE ALUMINUM HEADS
Aluminum cylinder heads deliver strength greater than or equal to cast iron with considerably less weight. Valves are configured to optimize swirl in the combustion chamber. As air flows in it rotates and mixes more thoroughly with the fuel, allowing more complete combustion for lower emissions and improved fuel efficiency.
The Duramax also has four valves per cylinder--the standard for contemporary diesels. Four valves allow more air to flow in and out of engine, particularly at higher rpm; more air means better combustion and more horsepower. While four-valve design is more common in larger, commercial-grade diesels or those designed specifically for passenger cars, it is relatively new in pickup applications. The Duramax borrows it four-overhead-valve design from big-rig engines: One pushrod-actuated rocker with smooth-operating roller lifters operates each pair of intake and exhaust valves.
SINTERED STEEL VALVE SEAT INSERTS
Sintered powder metal valve seats are forged and pressed into the aluminum heads. This process combines the weight and cooling advantage of aluminum with the wear characteristics of hardened steel, and is not used in competitive engines.
COMMMON-RAIL DIRECT PILOT INJECTION
The state-of-the-art direct diesel injection system was developed with Robert Bosch Corp. Direct fuel injection offers a number of advantages over indirect injection because it delivers fuel directly above the piston, rather than to a pre-chamber in the cylinder head. Other things equal, direct injection means more power and more complete combustion, with faster cold temperature starting. Perhaps most important, it delivers 15-20 percent better fuel economy than indirect injection. Less fuel burned means lower exhaust emissions.
The key to making direct injection work, and to delivering fuel directly to the middle of the combustion chamber, is overcoming the immense pressure created by pumping pistons in a diesel engine with 17:1 compression. The Duramax 6600 addresses this problem with a single fuel rail feeding injectors on each cylinder bank. A pump pressurizes fuel in the rail beyond 23,000 psi; solenoid valves on each injector open to deliver fuel to the cylinders. Managed by the engine's Engine Control Module, the injectors deliver precisely equal amounts of fuel to each cylinder at a constant pressure. The result is smoother, more uniform combustion and less fuel consumption for the same output level.
The Duramax's sophisticated control electronics allow another advance called pilot injection--particularly beneficial in reducing noise in compression-ignition engines. Pilot injection opens the fuel injectors to deliver an initial, small spray of fuel. After a slight pause, the injectors deliver the main pulse of fuel. This two-stage fuel delivery means that combustion starts small and builds progressively, greatly reducing the hard knocking sound typically associated with diesel engines. Pilot injection results in smoother starts and much quieter operation than conventional small diesel injection systems.
V-MOUNTED INTERCOOLED TURBOCHARGER
Delivering maximum boost pressure of 20 psi, the turbocharger is mounted in the valley (or V) between the cylinder heads. Exhaust pressure to spin the turbo's compressor comes from tubes running up the back of the engine, behind the cylinder heads, from each exhaust manifold. V mounting affords a number of advantages, starting with compact packaging. The turbocharger is integrated in the engine, rather than mounted outside of it like an alternator or air conditioning compressor, and reduces noise and vibration.
The Duramax 6600 also has a charge cooler, or intercooler, to maximize the benefits of the turbocharger. A turbo creates more power because it force-feeds compressed air to the cylinders, and the cooler that air, the better. The Duramax's air-to-air intercooler is mounted in front of the coolant radiator. Compressed air from the turbo goes forward through the intercooler, where it is cooled and directed back into the intake manifold. The cooled air is denser, delivering more oxygen to the combustion chambers. In addition to creating more power, the intercooler also improves long term durability by lowering the engine's internal operating temperature.
INTEGRAL OIL COOLER
Cooler oil means longer engine life, so the Duramax 6600 is equipped with a highly efficient integral oil cooler. The oil cooler is mounted directly in the left side of the block, and provides several advantages over conventional remote-mounted coolers. It requires no plumbing to connect it to the coolant radiator, which means fewer potential leak sources. Engine coolant flows directly from the water pump through the oil cooler before it travels through the rest of the engine block. The oil is cooled first, and more effectively than with remote-mounted coolers.
GEAR-DRIVEN WATER PUMP
The gear-driven water pump is common in larger commercial diesels, but not V engines designed for pickup applications. In most V engines, the cooling fan and water pump are connected, and driven by the same belt. In the Duramax, the water pump is driven directly by gears from the crank. Metal gears are more robust than rubber belts. Likewise, driving the pump with gears reduces stress on the accessory drive belt, increasing the belt's useful life. And if the belt breaks or slips off the crank pulley the water pump continues to operate and cool the engine.
1000-WATT BLOCK HEATER
A high-capacity block heater uses a compact element that hangs in a water jacket on the right side of the block. Powered by a standard 110-volt electrical outlet, the block heater is rated at 1000 watts, compared to 600 watts in the 6.5-liter L65 diesel.
The Duramax 6600 features a number of systems that improve cold starting, including direct pilot injection and a multi-function fuel filter. The filter assembly has a water separator that removes condensation from the fuel, as well as a heater that raises fuel temperature to at least 57 degrees Fahrenheit. As a result, the engine is capable of cold starts to minus 20 degrees without assistance from the block heater.
The block heater extends cold-start capability to minus 40 and can provide benefits in less extreme temperatures. The heating element keeps coolant warm and oil less viscous. The oil flows more freely immediately after the engine turns over, reducing wear during the crucial cold-operation period and full temperature is reached more quickly.
EASY SERVICE FEATURES AND LOW COST OF OWNERSHIP
Several design features make it easier to service the engine. The Duramax 6600's compact size leaves more space around the engine when it is installed in the vehicle. The timing-gear train and all timing components are at the front of the engine for easy access. The fuel filter is located in the right rear corner of the engine, and it can be removed by the customer simply by leaning into the engine compartment.
The recommended oil-change interval is 7500 miles, while the coolant is good for five years or 50,000 miles. As noted, components like the V-mounted turbocharger, integral oil cooler and gear-driven water pump greatly reduce external engine plumbing or perishable components, further limit potential leak sources or failures. Yet the single biggest contributor to low cost of ownership is the initial cost of the engine, as a component of vehicle purchase price. Design elements such as linerless cylinders and fractured connecting rods deliver long-term durability and performance with reasonable manufacturing cost.
The Duramax 6.6-liter V8 diesel combines the best design and manufacturing elements of two worlds. It was developed jointly by Powertrain and Isuzu Motors, one of the world's leading manufacturers of all types of diesel engines. Isuzu applied its expertise to developing basic engine hardware; Powertrain, with its vast experience with a wide range of climate conditions, driving cycles and ownership demands, was responsible for engine control systems and electronics.
The Duramax 6600 will be built as a joint venture at GM's expanded, thoroughly modernized engine plant in Moraine, Ohio, and launched in model year 2001 as an option on 2500HD and 3500 GMC Sierra pickups, crew cabs and chassis cabs.
The current 6.5-liter L65 diesel will continue in GMC Savana vans. Components such as the nitrided crank, deep-skirt, induction-hardened block, oil spray piston cooling, fractured connecting rods and sintered steel valve seats are expected to give the Duramax 6600 class-leading durability. Its targeted operating life is at least 250,000 miles without major failures.
With the new LQ9 Vortec 6000 and L18 Vortec 8100 gasoline engines, the Duramax 6600 completes the most powerful line of heavy-duty pickup engines in the market. Each exceeds published output ratings for comparable heavy-duty pickup engines from Ford and Dodge in model year 2000.
The bottom line on the Duramax 6600 says it all. This all-new diesel V8 beats the competition in virtually every category, with more horsepower, more torque and higher specific output than the heavy-duty diesels from Dodge and Ford in model year 2000.
Published figures for model year 2000 give Ford's 7.3-liter diesel V8 235 horsepower at 2700 rpm and 500 lb-ft of torque at 1600 rpm. Dodge reports 230 horsepower at 2700 rpm and 450 lb-ft of torque at 1600 rpm for its 5.9-liter line six Cummins diesel.
The Duramax is also more compact and considerably lighter, with noise, vibration and harshness control on par with gasoline engines. It is 19 percent more fuel efficient than the 6.5-liter L65 diesel, according to the development team, and its mileage ratings are expected to surpass those delivered by diesels from Dodge and Ford.
"We think this is going to the best engine in this market, hands down. It is certainly high-tech but it's also incredibly strong and durable. It really does have everything. It's also been a good learning process for Powertrain and the corporation. Our cooperation with Isuzu showed us some opportunities and design techniques that can carry over to other products." --Jack Blanchard, Total Integration Engineer, LB7 V8.
Devil Girl 2006 2500HD LBZ Ex-Cab 4x4
EFI Live tuned by IdahoRob,MPI twins installed by BigDipper,PPE lift pump, BigDipper 30% injectors, BigDipper Trans Precion ML converter.PPE Twin Cp3's.
Alot Of thanks To Kat & Pat at duramax diesels, Joe & Dan at PPE,George aka BigDipper
RIP LBZ 6/1/08@5:44pm she was strong
She's Alive again
Born on July 27, 2008, 11:59:02 PM
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