L76 Specs

[GRRRR8]

6.0 liter
364 CID / 5967cc
90 Degree V-8 alum block/heads
OHV 2 valves per cylinder
10.4:1 compression
361HP @ 5300 RPM
385 LB-FT @ 4400 RPM
11.3LB / HP


http://media.gm.com/us....ex.html (http://media.gm.com/us/gm/en/news/events/autoshows/07chicago/brands/pontiac/index.html)

[Steve]

2008 “L76” 6.0L V8 (L76)

6.0L Gen IV V8 (L76) CAR ENGINE
2008 Model Year Summary

• Active Fuel Management Calibrated For Pontiac G8 GT Passenger Car
• Structural Cast Aluminum Oil Pan Specific To G8
• Intake Manifold From LS3 Corvette Application
• Induction System Specific To G8
• Exhaust Manifolds Design Specific To G8
• Electronic Throttle Control From LS3 V8 Application
• Gen IV Cast Aluminum Cylinder Block
• High-Flow Cylinder Heads
• Returnless Fuel Injection with Stainless Steel Fuel Rail
• Advanced Electronic Throttle Control Similar To LS3 V8
• E38 Engine Control Module
• 58X Ignition System
• Enhanced Noise, Vibration and Harshness Control
• Smaller Ignition Coils From LS3 V8
• Iridium Tip Spark Plugs


6.0L V8 (L76)
The 6.0L (L76) V8 is a cast aluminum block V8 with GM’s industry leading Active Fuel Management (AFM) technology. For 2008, the Vortec 6.0L V8 VVT (L76) is found in the Chevrolet Avalanche, Silverado and Suburban, and the GMC Sierra and Yukon XL models with an industry first cam-in-block variable valve timing (VVT) system. The Pontiac G8 is the first passenger car application for the L76, but without VVT.

This engine is from the family of fourth-generation descendents of one of the most important and successful engines in automotive history—the original Chevrolet small-block, which debuted in 1955. The Gen IV V8’s feature technology creators of the first small block could not have imagined, yet they share one fundamental trait with the original: a market-leading balance of performance, sophistication, economy and durability.

The Small Block Vortec V8s have fueled GM’s leadership in truck sales because they provide the right technology for the job, and now this technology is expanded to rear-drive high-performance passenger cars with the 6.0L (L76).

Full Description of New And Updated Features

Active Fuel Management Calibrated For Pontiac G8 GT Passenger Car
The aluminum-block Gen IV 6.0L (L76) features GM’s Active Fuel Management technology (AFM). AFM temporarily de-activates four of the 6.0L’s cylinders under light to moderate load conditions. It should increase fuel economy approximately 6 percent under the federal government’s required testing procedure and potentially more in certain real-world driving conditions. Yet V8-powered rear-drive performance vehicles don’t have to compromise on the outstanding peak horsepower of the 6.0L (L76) to go farther on a tank of gas.

Active Fuel Management stems from a simple premise: most V8 cars have more power than owners demand in all conditions. With AFM, owners have a choice to save fuel during routine commuting. The 6.0L (L76) saves fuel by using only half of the 6.0L’s cylinders during some driving conditions, and seamlessly reactivates the other cylinders when a driver demands full power for acceleration.

Managed by the sophisticated E38 engine control module (ECM), AFM automatically shuts down every second cylinder, according to firing order, during light-load operation. In engineering terms, this allows the working cylinders to achieve better thermal, volumetric and mechanical efficiency by reducing heat loss, combustion loss and friction, and lowering cyclical combustion variation from cylinder to cylinder. As a result, AFM delivers better fuel economy and lower operating costs. Perhaps the most sensible thing about AFM is that it harnesses the engine’s existing capabilities, starting with the potential designed into the E38 ECM. The only mechanical components required are special valve lifters for cylinders that are deactivated, and their control system. The incremental cost for the customer is nominal per engine. Active Fuel Management relies on three primary components: De-ac (for deactivation) or collapsible valve lifters, a Lifter Oil Manifold Assembly (LOMA), and the ECM.

One of the most sophisticated engine controllers extant, the E38 ECM measures load conditions based on inputs from vehicle sensors and interprets that information to mange more than 100 engine operations, from fuel injection to spark control to electronic throttle control. AFM adds an algorithm to the engine control software to manage cylinder deactivation and reactivation. When loads are light, the E38 automatically closes both intake and exhaust valves for half of the cylinders and cuts fuel delivery to those four. The valves re-open to activate all cylinders when the driver demands brisk acceleration or full torque to move a load. The engine’s electronic throttle control (ETC) is used to balance torque following cylinder deactivation or reactivation. The transition takes less than 20 milliseconds, and can’t be detected by the driver.

Valve lifters are operated by the engine’s camshaft, and lift a pushrod that operates the valves in the cylinder head. In the Gen IV 6.0L (L76), the De-Ac lifters are installed in cylinders 1, 4, 6 and 7, while the remaining cylinders use conventional lifters. The hydraulically operated De-Ac lifters have a spring-loaded locking pin actuated by oil pressure. For deactivation, hydraulic pressure dislodges the locking pin, collapsing the top portion of the lifter into the bottom and removing contact with the pushrod. The bottom of each De-Ac lifter rides up and down on the cam lobe but the top does not move the push rod. The valves do not operate and combustion in that cylinder stops. During reactivation, the oil pressure is removed, and the lifter locks at full length. The pushrods, and therefore the valves, operate normally.

The final AFM component is the LOMA. This cast-aluminum assembly is installed in the valley of the 6.0L (L76) in place of a conventional engine block cover. The LOMA holds four solenoids, control wiring and cast-in oil passages. The solenoids are managed by the ECM, and each one controls oil flow to a De-Ac Lifter, activating and de-activating the valves at one cylinder as required for Active Fuel Management.


The fuel injectors in the Gen IV 6.0L (L76) are identical for all cylinders; those feeding the de-activated cylinders are simply shut down electrically by the ECM during de-activation. When the cylinders are deactivated, the engine effectively operates as a V4. AFM operation is load based, as measured by the ECM using dozens of inputs, overlain with the driver’s demand for power as measured by throttle application. AFM’s response time varies with oil temperature, but in all cases is measured in milliseconds. Operation is always transparent to the driver. The engine returns to V8 mode the instant the controller determines that acceleration or load requires additional power.

The benefits are substantial. Active Fuel Management does not effect exhaust emissions, and it will reduce overall emissions significantly, including greenhouse gases such as CO2, to the extent that less fuel is used. Further, the savings reflected in EPA numbers may not account for AFM’s full impact. Owners who primarily travel long distances at steady speeds will see substantially greater fuel-economy improvements. Because of the reduced mass of the Pontiac G8 GT compared to the full-size trucks which use the majority of the Gen IV V8 engines, the calibrations for switching from a V4 powered configuration to a V8 configuration have been modified to optimize efficiency.

Structural Cast Aluminum Oil Pan Specific To G8
The 6.0L (L76) V8 engine is currently available in five nameplates of passenger cars from GM division Holden in Australia, and part of the development of the engine included a unique cast aluminum oil pan that adds structure to the Gen IV aluminum block, increasing engine stiffness and reducing noise. To facilitate the Active Fuel Management system not normally used in the Holden applications, an oil return valve was added to the pan.

Intake Manifold From LS3 Corvette Application
Packaging the 6.0L (L76) V8 under the lower hoodline of the G8 GT passenger car required a lower intake system than is used by the engine in truck applications, and so the thoroughly developed intake from the current LS3 6.2L V8, new in the Corvette for 2008, is used with the 6.0L (L76).

Intake Air Chamber Specific To G8
The airbox leading to the throttle body and intake system is optimally designed for best flow for a passenger car.

Exhaust Manifolds and Design Specific To G8
As with the intake airbox, the exhaust manifolds and exhaust system designed specifically for passenger cars are used with the G8 GT application.

Electronic Throttle Control from LS3 Corvette Application
The advanced and sophisticated electronically controlled throttle control and integrated cruise control used on the LS3 Corvette application is also used on the 6.0L (L76) V8.

Gen IV Cylinder Block
The Gen IV cylinder block shares two key design elements with GM’s original small block V8: A 90-degree cylinder angle with 4.4 inch bore centers. Beyond that, the latest small block applies design, casting and machining technologies that were unfathomable in the 1950s.


The Gen IV block debuted in 2005 as the foundation for the 400-hp LS2 V8 in the Chevrolet Corvette, Cadillac CTS-v and Pontiac GTO, which was also developed as a Holden application. The new 6.0L (L76) block applies all the improvements that were developed from the LS2.
.
Developed with the latest math-based tools and data acquired in GM’s racing programs, the new block provides an exceptionally light, rigid foundation for an impressively smooth engine. Its deep-skirt design helps maximize strength and minimize vibration. The bulkheads accommodate six-bolt, cross-threaded main-bearing caps that limit crank flex and stiffen the engine’s structure. The structural oil pans further stiffen the powertrain in all applications, car or truck.

The new-generation small block is cast with oil ports in its V, or valley, to accommodate advanced technologies in the “L76” 6.0L, including Active Fuel Management (AFM) cylinder deactivation. The Lifter Oil Manifold Assembly (LOMA), a key component of AFM, installs in the valley in place of a conventional engine block cover. As a result, knock sensors located in the valley on the Gen III V8 have been moved to the outside of the engine block, while the cam sensor has been moved from the rear of the block to the front cover.

The Gen IV 6.0L is offered with either a conventional cast-iron (LY6) for truck applications or an aluminum engine block (L76) for either truck or car applications, giving customers a choice and allowing technology appropriate to the application. The lighter aluminum block allows vehicle engineers more latitude in tailoring weight distribution, and can mean a slight improvement in fuel economy. The Gen IV aluminum block is cast from A356-T6 alloy, with pressed-in iron cylinder liners. It weighs roughly 100 lbs. less than a comparable cast-iron engine block.

High-Flow Cylinder Heads
The Gen IV 6.0L (L76) is fitted with high-flow cylinder heads, based on those developed for the high-performance LS2 and LS6 car V8s. These heads have offset rockers, like those in the LS7. They also have larger valves than the Vortec 6.0L V8 heads used in truck applications, and increase airflow in and out of the engine for higher horsepower. Yet the 6.0L (L76) heads maintain a compression ratio and calibrations that allow these engines to operate on regular gas.

Returnless Fuel Injection with Stainless Steel Fuel Rail
The 6.0L (L76) is equipped with a "returnless’’ fuel injection system, also known as a demand system, and the latest-generation Multec injectors with USCAR connectors. The Gen IV V8s represent one of GM’s first applications of USCAR-standard electrical connectors for the fuel injectors. The standard was developed to promote common, reliable connections across the auto industry and streamline regulatory oversight. The connectors are more compact than previous connectors, and designed for improved sealing.

Originally introduced on the Gen III Vortec V8s, returnless fuel injection represented a paradigm shift for GM, developed to improve performance and decrease evaporative emissions. Previously, Vortec 6.0Ls used a return line between the engine and the fuel tank to manage fuel pressure by bleeding off excess fuel at the fuel rail and returning the excess to the tank. The new system eliminates the return lines and moves the fuel pressure regulator from the fuel rail on the engine to the fuel tank. Because it delivers only the amount of fuel needed by the injectors, and returns no fuel to the gas tank, the returnless system essentially eliminates heat transfer from the engine to tank. This reduces the amount of vapor generated in the tank and captured by the vehicle’s Onboard Refueling Vapor Recovery (ORVR) system.

With the returnless system, the 6.0L (L76) uses a fuel rail manufactured of stainless steel. Previous versions used a nylon rail. The stainless steel rail allows installation of baffles that manage fuel pulses in the returnless system and reduce noise.

Advanced Electronic Throttle Control
GM Powertrain has led the industry in applying electronic throttle control (ETC) to its V8s, and all applications of the Gen IV are now equipped with ETC. The Gen IV 6.0L (L76) introduces the next generation ETC.

With ETC, there is no mechanical link between the accelerator pedal and the throttle body. A sensor at the pedal measures pedal angle and sends a signal to the engine control module (ECM), which in turn directs an electric motor to open the throttle at the appropriate rate and angle. ETC delivers a number of benefits to the customer. Besides throttle pedal angle, the ECM measures other data, including the transmission’s shift patterns and traction at the drive wheels, in determining how far to open the throttle. ETC delivers outstanding throttle response and greater reliability than a mechanical connection, which typically uses a cable that requires adjustment—and sometimes breaks. Cruise control electronics are integrated into the system, further improving reliability and simplifying engine assembly.

The Gen IV 6.0L (L76) takes ETC to the next level by taking advantage of capability built into its advanced E38 ECM (below) and further streamlining the system. Its up-integrated ETC system eliminates a Throttle Actuator Control (TAC) module. The previous TAC takes commands from the ECM and then operates the electric motor that opens and closes the throttle. The E38 manages the throttle directly, without a TAC. Eliminating the TAC reduces cost and improves reliability. The direct link between the ECM and the throttle motor improves throttle response time (albeit in millisecond increments that are not apparent to the driver) and improves system security by removing a device (the TAC) that must be monitored for malfunction

E38 Engine Control Module
An advanced controller manages the multitude of operations that occur within the 6.0L (L76) every split second. The E38 is the mid-line controller in GM Powertrain’s family of engine control modules (ECM), which direct nearly all the engines in Powertrain’s line-up. In combination with advanced sensor technology, the E38 includes the ability to control and synchronize advanced technologies such as Active Fuel Management.

The E38 features 32-bit processing, compared to the conventional 16-bit processing in previous V8 engines. The E38 operates at 59 MHz, with 32 megabytes of flash memory, 128 kilobytes of RAM and a high-speed CAN bus, and it synchronizes more than 100 functions, from spark timing to cruise control operation to traction control calculations. The E38 works roughly 50 times faster than the first computers used on internal combustion engines in the late 1970s, which managed five or six functions.

The family strategy behind GM’s new ECMs allows engineers to apply standard manufacturing and service procedures to all powertrains, and quickly upgrade certain engine technologies while leaving others alone. It creates both assembly and procurement efficiencies, as well as volume sourcing. In short, it creates a solid, flexible, efficient engine-control foundation, allowing engineers to focus on innovations and get them to market more quickly. The family of controllers means the ECM and corresponding connectors can be packaged and mounted identically in virtually every GM vehicle. Powertrain creates all the software for the three ECMs, which share a common language and hardware interface that’s tailored to each vehicle.

The E38 also applies a rate-based monitoring protocol sometimes known as run-at-rate diagnostics. Rate-based diagnostics improve the robustness of the Onboard Diagnostics System (OBD II) and ensure optimal performance of emissions control systems. The new software increases the frequency at which the ECM checks various 6.0L (L76) systems, and particularly emissions-control systems such as the catalytic converter and oxygen sensors. Rate-based diagnostics more reliably monitor real-word operation of these systems, and allow regulatory agencies to more easily measure and certify emissions compliance.

58X Ignition System
The 6.0L (L76) has an advanced 58X crankshaft position encoder to ensure that ignition timing is accurate throughout its operating range. The new 58X crankshaft ring and sensor provide more immediate, accurate information on the crankshaft’s position during rotation. This allows the E38 ECM to adjust ignition timing with greater precision, which optimizes performance and economy. Engine starting is also more consistent in all operating conditions.

In conjunction with 58X crankshaft timing, the Gen IV V8s apply the latest digital cam-timing technology. The cam sensor is now located in the front engine cover, and it reads a 4X sensor target on the cam sprocket. The target ring has four equally spaced segments that communicate the camshaft’s position more quickly and accurately than previous systems with a single segment. It provides precise control required for variable valve timing.

The dual 58X/4X measurement ensures extremely accurate timing for the life of the engine. Moreover, it provides an effective back-up system in the event one sensor fails.

Enhanced Noise, Vibration and Harshness Control
The Gen IV V8s were developed for quieter operation, with virtually every system or component reviewed in an effort to reduce noise, vibration and harshness. Quiet features built into the engines are complemented by improved engine cradles and mounting systems. These help reduce vibrations transmitted through the chassis and into the passenger compartment.

The NVH enhancements include floating pin pistons, which reduce noise and increase durability. These pistons have wrist pins that “float” inside the rod bushing and the pin bores in the piston barrel. Compared to a conventional fixed pin assembly, in which the connecting rod is fixed to the piston’s wrist pin and the pin rotates in the pin bore, the floating pins reduce stress on the pin. They allow tighter pin to pin-bore tolerances and reduce noise generated as the piston moves through the cylinder. To further reduce wear, the pistons are coated with a polymer material, which limits bore scuffing, or abrasion of the cylinder wall over time from the piston’s up-down motion. The polymer coating also dampens noise generated by the piston’s movement. The result for the customer is less engine wear, improved durability and quieter operation.

The Gen IV V8s also feature a new heavy-duty timing chain developed expressly for quiet operation. The chain, which connects the cam and crankshaft, is validated for 200,000 miles of operation and fitted with a new leaf-spring dampener. Even the most durable chains stretch with time. In many engines they must be adjusted or replaced at scheduled intervals. The chain dampener on the 6.0L (L76) maintains optimal chain tension for the life of the engine and eliminates any flapping motion that might develop as the chain stretches with mileage. It ensures that the timing chain operates as smoothly and quietly as new, even as the engine accumulates high mileage.

Exhaust manifolds were developed to improve durability and sealing and reduce operational noise. Cast nodular iron was the material of choice for its basic durability and excellent heat management properties. The manifolds feature saw cuts along their flange, or the surface where they mate to the engine. Originally developed for the big-block Vortec 8.1L for truck applications, these cuts split the flange into three separate sections, allowing each section to move under extreme hot-cold temperature fluctuations without interacting with, or creating stress on, another section. The cuts virtually eliminate friction on –and movement of—the exhaust manifold gaskets. This helps ensure proper sealing for the life of the engine and reduces the chance of gasket failure.

The exhaust manifolds are fitted with new triple-layer heat shields fabricated from stainless steel and insulating material. The shields limit heat transfer from the engine to the engine bay, allowing the 6.0L (L76) to reach optimal operating temperature more quickly, yet reducing heat in the engine compartment once that temperature is achieved. They also dampen the sound of exhaust gas rushing through the manifolds and further reduce the amount of engine operational noise that finds its way into the vehicle interior.

Smaller Ignition Coils
The individual coil-near-plug ignition on the 6.0L (L76) features advanced coils originally developed for the LS2, the new LS3, and LS7 Corvette V8s. The new coils are smaller and lighter than those used on previous “L76” V8s, and while they are still mounted on the rocker covers, they attach with a new mounting bracket that simplifies engine assembly. An individual coil for each spark plug delivers maximum voltage and consistent spark density, with no variation between cylinders.

Iridium Tip Spark Plugs
Improvements to the ignition system on the 6.0L (L76) include advanced spark-plug technology. Its spark plugs have an iridium electrode tip and an iridium core in the conductor. The iridium plug has a recommended life of 100,000 miles, but it offers a number of advantages over the platinum-tip plugs previously used in the Gen IV V8s.

The iridium spark plug has higher internal resistance, maintaining optimal spark density over its useful life. Its “self-cleaning” properties are improved, decreasing potential for plug fouling and further reducing the likelihood of maintenance over the 100,000-mile plug life. The electrode design improves combustion efficiency for maximum fuel economy and minimum emissions. Finally, iridium is more plentiful than platinum, reducing the plug’s material cost and preserving scarce noble metals.


Overview

Currently the development of the Gen IV 6.0L (RPO L76) V8, one of the fourth-generation descendents of the legendary Chevrolet small-block, includes applications in trucks that have achieved sales leadership through a balance of performance, sophistication, economy and durability.

The cast-iron block Vortec 6.0L (RPO LY6) was developed for heavy-duty applications, such as the all-new Chevy Silverado and GMC Sierra 2500 HDs. The LY6 has undergone the most rigorous lab- and road-testing process in small-block history. It’s validated to achieve 200,000 miles of operation in typical applications. The aluminum-block 6.0L was developed for maximum towing capability in vehicles like the Chevy Suburban. Its Active Fuel Management cylinder-deactivation technology improves fuel-economy when the trailer is empty or left behind.

All Gen IV 6.0Ls build on the solid foundation laid by their immediate predecessors: The Gen III Vortec V8s. Gen III introduced a host of advanced technologies to the overhead-valve V8, including aluminum cylinder heads, a thermoplastic intake manifold and electronic throttle control. Cylinder heads were designed with replicated ports that are identical in every detail, allowing constant cylinder-to-cylinder airflow. The valvetrain was developed on the belief that lighter is more efficient. A steel camshaft provides excellent durability. Steel roller rockers add stiffness, allowing greater engine speed with less vibration. Hydraulic roller lifters reduce friction for better fuel economy and wear resistance.

With their increase in output and fuel efficiency, the Gen IV small blocks share their predecessors’ low-maintenance requirements. The spark plugs extend anticipated plug life to 100,000 miles, while the coolant maintains its cooling and corrosion-inhibiting properties for 150,000 miles. Scheduled maintenance is limited to oil changes, and thanks to GM’s industry-leading Oil Life System, a customer should never pay for an unnecessary change. The ECM in all Gen IV 6.0L V8 engines records engine temperature, length of operation at a given temperature and several other operating parameters, and then indicates an oil change when it's actually needed, rather than according to a predetermined interval.

[Steve]

2008 "L76" 6.0L V8 ( L76 )

Type: ............................6.0L Gen IV V8 Small Block
Displacement: ...............5967cc (364 ci)
Compression ratio:.........10.4:1
Valve configuration: ........overhead valves (2 valves per cylinder)
Assembly site:...............Silao
Valve lifters:....................hydraulic roller
Firing order: ...................1 - 8 - 7 - 2 - 6 - 5 - 4 - 3
Bore x stroke:.................101.6 x 92mm
Fuel system:..................sequential fuel injection ( SFI )
Fuel type:.......................premium recommended
Fuel shut off:...................6000 RPM
Emissions controls:.........catalytic converter; three-way catalyst; positive crankcase ventilation
Engine Orientation:..........Longitudinal
Valves per cylinder:.........2
Bore Center (mm):...........111.76
Engine Mass:..................TBD

Applications: hp ( kw ) / Torque: ( Nm )
Pontiac G8 GT
361( 268 kW ) @ 5300 / 385( 520 Nm ) @ 4400 rpmSAE CERTIFIED

MATERIALS
Block: ............................cast aluminum
Cylinder head: ................cast aluminum
Intake manifold:...............composite
Exhaust manifold: ...........cast nodular iron
Main bearing caps: ..........powder metal
Crankshaft: .....................cast nodular iron with undercut and rolled fillets
Camshaft:........................hollow steel
Connecting rods:..............powder metal

Additional features:
.........................extended life spark plugs
.........................extended life coolant
.........................Active Fuel ManagementTM
.........................Oil Life System
.........................electronic throttle control
.........................extended life accessory drive belt

[ProStreet]

Thanks for the post!

[Crazy Paul]

Here's the reply I got from GM Performance Parts when I asked about the L76 cam specs. I also asked if it was true that the grind was different between the de-activate cylinders and the normal cylinders.

Answer 1 = 200/208......0.472/0.479
Answer 2 = Yes



Re: L76 Stock Cam

--------------------------------------------------------------------------

AFM cylinders have slightly different grind ( a bit taller) to accomodate additional compliance of AFM parts --intent is lift event equivalence.



1.70 Exhaust Rocker Ratio
1.69 Intake Rocker Ratio

Lift:
@Cam @Valve
Exhaust: 0.282 0.479
Intake: 0.279 0.472

Cam Timing@0.004" Tappet Lift:
Open Close Adv. Duration
Exhaust: 71 BBDC 33 ATDC 284
Intake: 11 BTDC 91 ABDC 282


Cam Timing@0.050" Tappet Lift:
Open Close Duration
Exhaust: 40 BBDC 12 BTDC 208
Intake: 17 ATDC 37 ABDC 200
__________________
GM Performance Parts


Stock L76/L92 valve springs are rated to Max lift 0.530"

[GRRRR8]

Just some more GRRRR8 info from down under. Thanks Paul!

[GeorgeInNePa]

101.3mm x 92mm = 3.988" x 3.622"

[R.Penguin]

2008 "L76" 6.0L V8 ( L76 )

Type: ............................6.0L Gen IV V8 Small Block
Displacement: ...............5967cc (364 ci)
Compression ratio:.........10.4:1
Valve configuration: ........overhead valves (2 valves per cylinder)
Assembly site:...............Silao
Valve lifters:....................hydraulic roller
Firing order: ...................1 - 8 - 7 - 2 - 6 - 5 - 4 - 3
Bore x stroke:.................101.6 x 92mm
Fuel system:..................sequential fuel injection ( SFI )
Fuel type:.......................premium recommended
Fuel shut off:...................6000 RPM
Emissions controls:.........catalytic converter; three-way catalyst; positive crankcase ventilation
Engine Orientation:..........Longitudinal
Valves per cylinder:.........2
Bore Center (mm):...........111.76
Engine Mass:..................TBD

Applications: hp ( kw ) / Torque: ( Nm )
Pontiac G8 GT
361( 268 kW ) @ 5300 / 385( 520 Nm ) @ 4400 rpmSAE CERTIFIED

MATERIALS
Block: ............................cast aluminum
Cylinder head: ................cast aluminum
Intake manifold:...............composite
Exhaust manifold: ...........cast nodular iron
Main bearing caps: ..........powder metal
Crankshaft: .....................cast nodular iron with undercut and rolled fillets
Camshaft:........................hollow steel
Connecting rods:..............powder metal

Additional features:
.........................extended life spark plugs
.........................extended life coolant
.........................Active Fuel ManagementTM
.........................Oil Life System
.........................electronic throttle control
.........................extended life accessory drive belt
Holy shit! You should bind that and sell it as a book! :p

[third_shift|studios]

in lame-men's terms, what's the diff between the L76 and LS2?

[Crazy Paul]

The L76 is not as highly strung as the LS2.
The L76 has a lower compression ratio and a smaller camshaft. This allows it to run on lower quality (cheaper fuel).
The L76 also has features which enable it to "coast" with 4 of its 8 cylinders "shut down".

The only superior items the L76 have are the cylinder heads, but in stock form they cannot reach their full potential because of the tiny camshaft.

The stock L76 camshaft needs to be tiny because of the limitations inherent in the cylinder shut down system.

[99-LS1-SS]

Oh how I hate a tiny camshaft....

[MANOFSTEEL69]

Get a tiny camshaft enhancement.....I did and man did my confidence improve.....and the luck with the ladies hasn't been hurt either. ;)

[third_shift|studios]

so camshaft and DOD + better heads are the differences? interesting....and your saying up the cam shaft, and the engine really springs to life?

Can DOD be deprogramed? To me it always sounded like a future breakdown.

[third_shift|studios]

Oh how I hate a tiny camshaft....

that's what she said...

http://img.photobucket.com/albums/v141/DarkArtsDesign/garth.jpg

[99-LS1-SS]

so camshaft and DOD + better heads are the differences? interesting....and your saying up the cam shaft, and the engine really springs to life?

Can DOD be deprogramed? To me it always sounded like a future breakdown.

I would say if your going to have a new cam put in you should go ahead and do the DOD delete.

[G8GT594]

so camshaft and DOD + better heads are the differences? interesting....and your saying up the cam shaft, and the engine really springs to life?

Can DOD be deprogramed? To me it always sounded like a future breakdown.

It'll wake up with a cam. DOD can be tuned out, but the real problem lies with the actual parts that go along with DOD.

[third_shift|studios]

It'll wake up with a cam. DOD can be tuned out, but the real problem lies with the actual parts that go along with DOD.

i hear that, probably a bunch of weight...is the LS3 going to have DOD?

[99-LS1-SS]

I don't think it's a weight issue as much as the pieces being able to handle the additional stress that a larger cam brings.

[GeorgeInNePa]

i hear that, probably a bunch of weight...is the LS3 going to have DOD?

The auto GXP has the L99. It's a LS3 with a smaller cam and it has DoD.

Less hp than a LS3.

[99-LS1-SS]

The auto GXP has the L99. It's a LS3 with a smaller cam and it has DoD.

Less hp than a LS3.

I thought the GXP didn't have DoD in any version. I know the new Camaro will have it but I haven't heard of the GXP getting the L99.

[GeorgeInNePa]

I thought the GXP didn't have DoD in any version. I know the new Camaro will have it but I haven't heard of the GXP getting the L99.

I read this several times.

Don't worry, the M6 is DoD free. ;)

[Slizzo]

As far as I knew the GXP whether auto or stick has an LS3 in it.

Only differences are rear gears paired to the transmission choice.




Camaro SS Auto has an L99, Manual has an LS3.

[99-LS1-SS]

Can you point me to where you saw that George?

[GeorgeInNePa]

As far as I knew the GXP whether auto or stick has an LS3 in it.

Only differences are rear gears paired to the transmission choice.




Camaro SS Auto has an L99, Manual has an LS3.


I thought I read that it had the L99, but now all that I can find via Google is LS3.

Perhaps I was thinking Camaro?

Guess I was wrong.

[GeorgeInNePa]

Can you point me to where you saw that George?

I just spent 20 minutes looking.

I must have combined GXP and Camaro in my head.

[GRRRR8]

They are both LS3s. The auto is called an L99 and gets DOD and 400 HP I believe. The M6 is no DOD and is 403? I think.

[GeorgeInNePa]

The GXP LS3 is 415hp, that I know for certain. After reading all the stuff I just went through, that I KNOW.

;)

[99-LS1-SS]

The GXP LS3 is 415hp, that I know for certain. After reading all the stuff I just went through, that I KNOW.

;)

lol!

[Ktlplxm]

Just a question guys... has anyone put the real figure through a compression calculator? The torque numbers after tuning and all seem a little low... maybe the tranny and the driveshaft just eat up more than I expected...

[Crazy Paul]

Just a question guys... has anyone put the real figure through a compression calculator? The torque numbers after tuning and all seem a little low... maybe the tranny and the driveshaft just eat up more than I expected...

You're going to find different reports of the bore size of the L76 (4.000" or something less).
You'll also find different cc measurements of the heads (70, 69.x, 68.y or something else).

Until you measure those (critical) dimensions yourself then it's probably OK to believe GM when they say 10.4

[The Commodore]

How big is our throttle body in mm?

Maybe I missed it...
Mozilla/5.0 (Linux; U; Android 1.1; en-us; dream) AppleWebKit/525.10+ (KHTML, like Gecko) Version/3.0.4 Mobile Safari/523.12.2

[GeorgeInNePa]

How big is our throttle body in mm?

Maybe I missed it...
Mozilla/5.0 (Linux; U; Android 1.1; en-us; dream) AppleWebKit/525.10+ (KHTML, like Gecko) Version/3.0.4 Mobile Safari/523.12.2

90mm, Drive By Wire (electronic)

[The Commodore]

90mm, Drive By Wire (electronic)
Thanks. I thought it was 102 for some reason. Maybe that's what people are porting it out to?
Mozilla/5.0 (Linux; U; Android 1.1; en-us; dream) AppleWebKit/525.10+ (KHTML, like Gecko) Version/3.0.4 Mobile Safari/523.12.2

[GeorgeInNePa]

102mm is the new FAST intake and TB. The TB is not a Drive By Wire.

[Crazy Paul]

Thanks. I thought it was 102 for some reason. Maybe that's what people are porting it out to?
Mozilla/5.0 (Linux; U; Android 1.1; en-us; dream) AppleWebKit/525.10+ (KHTML, like Gecko) Version/3.0.4 Mobile Safari/523.12.2

Good luck porting it out to 102mm ID.

http://i2.photobucket.com/albums/y20/PerthPurplePenguin/car%20parts/LS2TB-1.jpg

[EcoBrick Bob]

I have a "board stretcher" that will help this along!

[[Daft]]

Hi, I'm new here and the G8 GT is on my short list for my new daily driver. I was just wondering if anyone knew if the nuts and bolts used on this car (engine, suspension ect.) were Metric or Imperial.

My last car was German made so I've got a garage full of Metric sockets and tools and I was just wondering if I needed to retool my garage if I were to pick up a G8 GT.

Thanks in advance

[Crazy Paul]

You're in luck.
Made in Australia = Metric


http://i2.photobucket.com/albums/y20/PerthPurplePenguin/Metric_system.jpg

[GeorgeInNePa]

You're in luck.
Made in Australia = Metric


http://i2.photobucket.com/albums/y20/PerthPurplePenguin/Metric_system.jpg

Wow, I had no idea that much of the world was wasting their time with the Metric System...

:nah:

[Crazy Paul]

Wow, I had no idea that much of the world was wasting their time with the Metric System...:nah:

Each system has it's merits and drawbacks. I'm glad I learnt both equally as a kid. It's only when people like NASA don't appreciate the difference between the two systems that there's usually a huge problem.

"NASA lost a $125 million Mars orbiter because a Lockheed Martin engineering team used English units of measurement while the agency's team used the more conventional metric system for a key spacecraft operation,"

[Gwizzy]

I feel so much smarter now!

[The Commodore]

Ok lets say you put a cam in an LS2 and you put a comparable cam in an L76 and get rid of the DOD crap. What will be making more power?

[13 QTR]

Ok lets say you put a cam in an LS2 and you put a comparable cam in an L76 and get rid of the DOD crap. What will be making more power?

I'd say the L76....bigger valves in the L76....

[Slizzo]

I'd say the L76....bigger valves in the L76....

Yeah, better heads stock on the L76 (L99 heads?) and better intake manifold on the L76 stock (LS3 intake manifold) should mean it would make better power all other parts being equal between the L76 and LS2.

[The Commodore]

Yeah, better heads stock on the L76 (L99 heads?) and better intake manifold on the L76 stock (LS3 intake manifold) should mean it would make better power all other parts being equal between the L76 and LS2.

That's what I'm trying to figure out. Is the L76 a LS2 bottom with an LS3 top? Or is it a different block? I know the camshaft is different.

And the heads are L92 heads IIRC. L99 is the DOD version of the LS3.

[Darkflow]

This may be somewhat of a stupid question, but is the L76 considered an LSX engine or not?

[99-LS1-SS]

Yes it is considered a LS series engine.

[supercharger]

Ok, so if the L76 uses a different block than the LS3 to get AFM, does that mean the L99 is the same block as the L76 but with a bigger AFM bumpstick that makes 400+HP and would swap right into a G8 GT? Or does the stock LS3 block have AFM capability built in and if so, why didn't they use it for the G8 GT?

Oh no, now I've gone crossed eyed.:wtf:

[Crazy Paul]

Ok, so if the L76 uses a different block than the LS3 to get AFM, does that mean the L99 is the same block as the L76 but with a bigger AFM bumpstick that makes 400+HP and would swap right into a G8 GT? Or does the stock LS3 block have AFM capability built in and if so, why didn't they use it for the G8 GT?


LS2 block is 6.0L, the LS2 has provision for AFM but none fitted. Add LS3 heads, LS3 intake to an LS2 6.0 block.......throw in AFM lifters and hardware = L76

LS3 block is 6.2L, the LS3 has provision for AFM but none fitted.
Throw on a cam phaser = L92
Throw in AFM lifters and hardware = L99

AFAIK the stock AFM cams are all much the same duration and profile.
The LS3 block with AFM (L99) wasn't produced until way after the G8-GT rolled off the production line IIRC.

[G8GT721]

Ok, so if the L76 uses a different block than the LS3 to get AFM, does that mean the L99 is the same block as the L76 but with a bigger AFM bumpstick that makes 400+HP and would swap right into a G8 GT? Or does the stock LS3 block have AFM capability built in and if so, why didn't they use it for the G8 GT?

Oh no, now I've gone crossed eyed.:wtf:

this sounds like a job for crazy paul^^

lol he responded before i posted my thought lol

[Darkflow]

Yes it is considered a LS series engine.

Ok, thanks.

[Larry GT]

All of your posts were very informative to this layperson/driver/etc. Now I've got a much better idea of what's under the hood, and instead of usually driving around town in the selective shift mode, I plan to take more advantage of the L7's designed 4 cylinders from 8.
Thank you.

[R.Penguin]

Boy, do I have a headache! :(

[jerseymike68]

Great information here

[-Ray-]

Ok, I hope you are paying attention here. You are going to have trouble posting pretty soon.

[GRRRR8]

Yes he will. :) Right now as a matter of fact.

[polo]

Yes he will. :) Right now as a matter of fact.

LOL!

did he just get banned?

[-Ray-]

Yep. He had more than 30 posts like his last one. I politely warned him in a pm.

[polo]

Yep. He had more than 30 posts like his last one. I politely warned him in a pm.

Yeah, I think i saw like 20 of them. Pretty funny that he got banned for being nice and grateful for "the information."!!

[SpeedRacerX]

Yeah, I kept seeing them fly-by on my cell phone and I was wondering what was going on with those posts...

[GRRRR8]

My Dumbshit detector was going off on this guy and Ray warned him before I could and then he signed back in and was doing it 3-4 times in a thread. How does the saying go........SAY BYE DUMBFUCK!

[G8DRIV3R]

i missed it damn what happened.....i guess the posts got deleted????

[Crazy Paul]

i missed it damn what happened.....i guess the posts got deleted????

Posting stuff like this (below) in many,many threads is textbook Troll activity.
Often you see it when someones main identity gets banned, they create a new ID. The new ID has a 0 post count, so to build up some "cred" the new ID posts worththless comments or just smilies multiple times on the board.....for the sole purpose of building the new ID.

Not saying that's what happened with mike68, but the signs were there.


Great information here

[UGotSmkd]

Yep. He had more than 30 posts like his last one. I politely warned him in a pm.

Weird. It only shows he posted 6 times.

[GRRRR8]

Over 40 were deleted of which 12 were in about 3 minutes AFTER being warned.

[grandmacpubah]

great info here

[PostalCherokee]

great info here

LOL, somebody testing the banned waters?

[616 of 933]

does anyone have the casting number for the heads?

[Crazy Paul]

does anyone have the casting number for the heads?

0821

some others that may have been used ---> 0823,5364 & 2716.

[polo]

0821

some others that may have been used ---> 0823,5364 & 2716.

I bet you've got all this info memorized, don't you? :)

[616 of 933]

0821

some others that may have been used ---> 0823,5364 & 2716.

this is the casting number i would look for on the heads like on the Lq9 was 317 and LS2 was 243 castings?

[Crazy Paul]

Yes



http://i2.photobucket.com/albums/y20/PerthPurplePenguin/car%20parts/L76/CAST5364_E_02.jpg

[616 of 933]

Thanks

[Crazy Paul]

I bet you've got all this info memorized, don't you? :)
Having a jump of 2 years on you guys certainly helps.

[99-LS1-SS]

Having a jump of 2 years on you guys certainly helps.

PLUS, you're superhuman!

[mtolivecracker]

PLUS, you're superhuman!

at least.

[REDWON]

I have to tell you guys that newbees to the GT (like me) need to read thru this entire thread.

It contains a storehouse of information. Thanks.

[UGotSmkd]

I didn't know that the LS3 intake would sacrifice HP.


"Interestingly, the L76 also powers the Pontiac G8 GT. The car version of the L76 drops variable valve timing and features an LS3 intake manifold, which sacrifices some hp while picking up some torque."

http://www.chevyhiperformance.com/tech/engines_drivetrain/shortblock/0912chp_performance_chevy_ls_engine_comparison/l76_vortech_4800_engines.html

[Crazy Paul]

I didn't know that the LS3 intake would sacrifice HP.
"Interestingly, the L76 also powers the Pontiac G8 GT. The car version of the L76 drops variable valve timing and features an LS3 intake manifold, which sacrifices some hp while picking up some torque."


Probably meant to type "which TOGETHER sacrifices"
Regardless look at the added bulk and visual monstrosity of the truck engine packaging which is necessary to incorporate the VVT and truck intake. Pretty sure GM made the right decision.

[UGotSmkd]

Probably meant to type "which TOGETHER sacrifices"
Regardless look at the added bulk and visual monstrosity of the truck engine packaging which is necessary to incorporate the VVT and truck intake. Pretty sure GM made the right decision.

No doubt. No complaints here :) I wasn't sure if they misstated (sp) the sentence.

[STRYKER_BLUE_09]

0821

some others that may have been used ---> 0823,5364 & 2716.

Is there any difference in the casting numbers?

[Crazy Paul]

Is there any difference in the casting numbers?

Yes.
A different casting process was used on a few of those, the as cast surface finish in the ports can be rough or smooth.
Search the numbers you are interested in on ls1tech.com and you'll find discussion there on the differences in the castings.

[barr1340]

I have a question earlier in the thread I think I saw if you changed to a bigger cam in the l76 some of the other parts would not hold up. If that is so when you change to a bigger cam what else should you change to be safe?

[Crazy Paul]

Sticky: Removing DOD hardware & fitting a larger camshaft
http://forum.grrrr8.net/showthread.php?t=462

[barr1340]

Thank you for leading me to that thread. I have another question for ya and I will appoligize ahead of time if you have answered it already. Going through the list everything up to number 10 is what the guy that is doing the work has planned. I asked him about the rest and he said " we dont have to do all that". Should I be concerned about that? This shop primarily mods ctsv's and he does great work. This is my daily driver never been raced and dont plan on it just want to wake up the engine. But I do want to be safe.

[barr1340]

Also is there a company here that you would recomend to do this upgrade?

[Crazy Paul]

Going through the list everything up to number 10 is what the guy that is doing the work has planned. I asked him about the rest and he said " we dont have to do all that".

10,11,&12.......amount to about total $110 worth of parts
For that you get a better than stock PCV (foul oily air inside the crankcase handling system), and proper blanking off of the AFM oil supply lines into the top of the block.
So for $110 you gain better oil control and remove un-used complex oil solenoids that can leak in future (hidden inside engine) and cause big problems.
13.......essential. Each old lifter tray is shaped to take 2 non-AFM lifters and 2 AFM lifters only. They cannot accept all non-AFM lifters which you'll be getting.
14.......essential. GM crank balancer bolt is torque to yield (single use only)....it needs to be removed to get your cam out.


Should I be concerned about that?
This shop primarily mods ctsv's and he does great work. This is my daily driver never been raced and dont plan on it just want to wake up the engine. But I do want to be safe.
Also is there a company here that you would recomend to do this upgrade?

I'd be concerned about a shop that doesn't understand the AFM system and have runs on the board with removal of same. Ask in your regional sub-forum for advice on where to go.

[barr1340]

thank u for the advice i really appriciate you taking the time to answer i will make sure its done right or not at all.

[shane]

Can someone tell me where the piston is? Is it at 0 Deck or in a little or what?

[G8GT721]

Bump, be browsing this again soon


Sent from my iPhone using Tapatalk

[STL_G8GT]

Can someone tell me where the piston is?

Ummm... in the block? :what::p:p dude if I remember right, at tdc it was perfectly flush with the deck. Is that what you mean?

[shane]

Ummm... in the block? :what::p:p dude if I remember right, at tdc it was perfectly flush with the deck. Is that what you mean?
Yea thats what im trying to find out... is it at 0 deck or lets say .005

[STL_G8GT]

http://forum.grrrr8.net/showthread.php?t=20652

.007 above according to measurements by Brian at RPT...

[shane]

Thanks!

[randallel]

I just found this and it is good information.