New for the LS1/LS2/LS6
GEN III 5.7L V-8 (LS1 and LS6) Car Engines
2005 Model Year Summary
FULL DESCRIPTIONS OF NEW OR CHANGED FEATURES
PONTIAC GTO LS1 APPLICATION ENDS
The 5.7L V-8 LS1 will no longer be offered in the Pontiac GTO. The new Gen IV 6.0L V-8 LS2 will become standard power for the GTO. LS1 production continues at GM Powertrain’s St. Catharines, Ontario engine plant for application in the Holden (GM Australia) V and W platforms, including the Monaro, Statesman, Commodore and Ute pickup-bed utility, as well as for marine use.
ELECTRONIC THROTTLE CONTROL FOR HOLDEN LS1
LS1s built for Holden are now equipped with electronic throttle control (ETC), replacing a conventional mechanical throttle. In the Holden LS1, there is no mechanical link between the accelerator pedal and the throttle. A potentiometer at the pedal measures pedal angle and sends a signal to the powertrain control module (PCM); the PCM evaluates this data and relays commands to a Throttle Actuator Module on the throttle body, which in turn directs an electric motor to open the throttle plate at the appropriate rate and angle. The entire process occurs in milliseconds.
ETC delivers a number of benefits to the customer. Besides throttle pedal angle, the PCM 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 in the throttle, further improving reliability and response time, and simplifying engine assembly.
The Holden ETC was adapted from the system used on Powertrain’s Gen III Vortec truck V-8s. It uses the same 75-mm throttle body, with an integrated “wraparound” throttle motor. The electric motor that operates the throttle plate is literally built around the throttle body for immediate throttle response, maximum reliability and simplified engine assembly.
FLOATING PIN PISTONS
The 5.7L LS1 and LS6 V-8s are equipped with new floating-pin pistons. First introduced on GM Powertrain’s Vortec 6000 H.0. V-8, these pistons feature wrist pins that “float” inside the rod bushing and the pin bores in the piston barrel. Previously, the LS1 and LS6 used a fixed-pin assembly, in which the connecting rod is fixed to the piston’s wrist pin, and the pin rotates in the pin bore. Snap rings now retain the wrist pin in the piston, while the rod moves laterally on a bushing around the pin. The floating pins were introduced as an interim change late in the 2004 model year.
The pistons, piston rings and connecting rods are identical to those used previously. The new floating-pin assembly allows tighter pin to pin-bore tolerances and reduces noise. The LS6 pistons were already validated for 200,000 miles of operation. The floating pin pistons should extend durability even further and reduce operational noise, even in brief, limited circumstances the customer may not have noticed to begin with.
RATE-BASED DIAGNOSTICS FOR LS6
The LS6 V-8’s P59 powertrain control module (PCM) uses a new monitoring protocol known as rate-based diagnostics. Rate-based diagnostics improve the robustness of the Onboard Diagnostics System (OBD II) and ensure optimal performance of emissions control systems.
With rate-based diagnostics, the PCM applies a new formula to manage OBD II. Essentially, new software increases the frequency at which the PCM checks various engine systems, and particularly emissions-control systems such as the catalytic converter, oxygen sensors and positive crankcase ventilation (PVC) system. Rate-based diagnostics more reliably monitor real-word operation of these systems, and allow regulatory agencies to more easily measure and certify emissions compliance. The new protocol allows the LS6 to meet more stringent OBD II requirements two years ahead of a mandate by the California Air Resources Board.
GF-4 ENGINE OIL
All LS6 V-8s will be shipped to customers with new engine oil that reduces engine deposits, extends oil change intervals, improves fuel economy and extends the life of emissions control systems. GM Powertrain has taken a leading role in developing and introducing the new oil, designated GF-4 (for “Gasoline Fueled, Standard 4’’) by the American Petroleum Institute.
GF-4 contains a new ash-free antioxidant ingredient and less phosphorous than the previous formulation (GF-3). The typical automotive engine now operates at a much higher temperature than an engine built 10 years ago. GF-4 is twice as resistant to oxidizing, which can present itself as foaming, at high operating temperatures. At the same time, GF-4 provides better low-temperature protection, reducing engine wear during the critical cold-start period. Lower phosphorus and sulfur content—chemicals that are harmful to catalytic converters—will extend anticipated catalyst life beyond 120,000 miles. Finally, GF-4 lowers friction overall and retains its optimal friction-reducing characteristics longer. The result is an anticipated improvement of 0.2-0.3 percent in an engine’s fuel economy, and longer oil change intervals.
Production of the LS6 with GF-4 will begin in fall 2004, ahead of an industry recommendation of April 30, 2005. This will allow vehicles with the LS6 to be tested for 2005 Corporate Average Fuel Economy (CAFE) standards with GF-4. GM’s industry-leading Oil Life System may be adjusted to account for the new oil. The owner’s manual in vehicles equipped with the LS6 will continue to recommend oil with the Starburst logo, which must be certified to GF-4 by May 2005.
Before there was an LS2 V-8 for the all-new 2005 C6 Corvette, there were the LS1 and LS6. While GM Powertrain’s new Gen IV LS2 has been rightfully praised as the ultimate in overhead-valve engine technology, one point should not be lost: the foundation for this remarkable engine, in both design philosophy and execution, was laid by the LS1 and LS6.
The 5.7L LS1 V-8 was unique in the automotive world when it was launched for model year 1997, and it remains a landmark in engine design—a true high-tech, high-performance cam-in-block car engine. The Gen III LS1 introduced leading-edge technologies to the grand tradition of the Chevrolet small block V-8, starting with all-aluminum construction, a thermoplastic intake manifold and drive-by-wire electronic throttle. Measured by mass, package size, performance or cost to the customer, the 5.7L LS1 matches the world’s best overhead-cam V-8s.
The Gen III LS1 shares little with the original Chevrolet small block, save the classic 4.4-inch bore centers. Launched in the 1997 C5 Corvette, the LS1 V-8 moved overhead-valve cylinder heads into a new era by aligning all valvetrain components in a single plane for minimal friction and maximum efficiency. From its introduction in the C5, the LS1 spread to other applications and the expansion has come with further refinement.
In 2001, Powertrain launched the ultra-high performance LS6 as part of the Corvette Z06 option. The process that turned the LS1 into the LS6 involved dozens of enhancements. The LS6 engine block added breathing windows in the hone overtravel area, allowing better bay-to-bay breathing, managing airflow inside the engine more efficiently and thus freeing the pistons' downward movement. The LS6 crankshaft featured a light-alloy torsional dampener, which balances shaft twist and flex and reduces vibration. Its pistons were made from a high-strength aluminum alloy; and its cylinder head was cast with smaller pent-roof combustion chambers than the LS1 head. Compression ratio increased from 10.1:1 to 10.5:1, improving thermal efficiency and increasing horsepower. Valve springs were strengthened, and the composite intake manifold was retooled to increase airflow to the intake ports. Maximum engine speed increased from 6200 to 6600 rpm.
In short, the LS6 reinforced the Z06 Corvette’s status as the unchallenged value leader among the world’s true high-performance sports cars.
Since launch of the LS6, the LS1 has benefited from many of the same improvements. In 2002, GM Powertrain offered the LS1 for marine use for the first time—in some applications with more power than the automotive versions. For 2004, both engines were fitted with the new P59 powertrain control module (PCM), which increased clock speed from 21 to 24 MHz, doubled memory to 1.1 megabytes, and provided one of the most sophisticated engine control systems in the industry. Also in 2004, the LS1 was installed in Pontiac’s re-launched GTO performance coupe; the LS6 was fitted in the new Cadillac CTS-V with specially developed engine mounts, bringing Z06-style performance to a true luxury sedan.
The 5.7L LS1 and LS6 take a back seat to no V-8 engine, delivering power, packaging and efficiency to match the world's best.
With all the improvement, the bottom line remains. The LS1 and LS6 exceed customer expectations with outstanding overall performance at modest cost to the customer.