Carryover Gen IV Small-Block V-8 for 2010 Chevrolet Corvette ZR1

2010 "LS9" 6.2L V-8 SC (LS9)

2010 Model Year Summary

Carryover Gen IV Small-Block V-8 for 2010 Chevrolet Corvette ZR1

Gen VI Supercharger with Twin Four-Lobe Rotors

Integrated Dual-Brick Air-to-Liquid Intercooler

Enhanced Gen IV Cylinder Block

Forged-Aluminum Pistons with Oil-Spray Cooling

Lightweight Reciprocating Assembly with Titanium Connecting Rods

Refined Low Overlap Cam

High-Flow Rotacast Cylinder Heads with High Performance Valves

Center-Feed Fuel System

Direct-Mount Ignition Coils

E67 Control Module

Dry-Sump Oiling System

Heavy-duty Accessory Drive

Stainless Steel Exhaust Manifolds with Close-Coupled Catalysts

Acoustic Engine Cover

Full Description of Carryover Features and Benefits

Carryover Gen IV Small-Block V-8 from 2009 MY for 2010 Chevrolet Corvette ZR1

The 638-hp 6.2L Supercharged V-8 (RPO LS9) is installed longitudinally in the Corvette ZR1, and offered only with the twin-disc Tremec TR6060 six-speed manual transmission. This engine is hand-assembled at GM's Performance Build Center in Wixom, Mich.

Simply put, the supercharged LS9 is the most powerful production engine ever offered by GM --a company with over a 100-year tradition of building very powerful engines. The LS9 generates 638 horsepower at 6500 rpm and 604 pound-feet of torque at 3800 rpm, certified by the Society of Automotive Engineers. Its specific output of 103 horsepower per liter, or 1.70 horsepower per cubic inch, is remarkable for an engine of its displacement. According to published figures, the LS9-equipped ZR1 has more horsepower and torque than the Dodge Viper SRT10, Ferrari 599 GTB Fiorano, and Porsche 911 GT2 Lamborghini Murcielago LP640- all benchmarks among exotic international sports cars.

Yet, thanks to its advanced engineering, the LS9 is civil at low speeds and remarkably tractable at all speeds. It idles with the smoothness of a luxury-car engine and generates 350 lb-ft of torque at just 1000 rpm, with 90 percent of its peak torque available from 2600 rpm to 6000 rpm. In short, the 6.2L Supercharged LS9 takes the combination of tremendous low-end pull and excellent high-rev horsepower that has long characterized Corvette small-block V-8s and extends it to an unprecedented level.

Gen IV Supercharger with Twin Four-Lobe Rotors

State-of-the-art supercharging technology is one key to the 6.2L LS9's remarkable performance. This Gen IV V-8 represents the first original-equipment application of Eaton's twin-rotor R2300 supercharger-one of the company's Twin Vortices Series (TVS), which introduce the sixth generation of joint Eaton/GM supercharger development. The LS9 supercharger displaces 2.3 liters, compared to more conventional superchargers of 1.5 liters or less, and generates maximum boost pressure of 10.5 pounds per square inch (0.72 bar).

A supercharger is essentially an air pump driven by the engine's crankshaft. It forces more air into the engine's combustion chambers than that engine could otherwise draw on its own. The increased volume of oxygen allows the engine to efficiently process more fuel, and thus generate more power.

The TVS takes supercharging technology to new levels of refinement and efficiency. Each of its two rotors has four distinct lobes, or spiral-shaped vanes that intermesh precisely with those on the other rotor as they spin at high speed. Efficiency gains with the four-lobe rotors are substantial, compared to comparably sized, previous-generation superchargers: approximately 20 percent more airflow, with an improvement in thermal efficiency up to 15 percent. Moreover, parasitic power loss-the amount of power the engine uses to operate the supercharger-is reduced 35 percent. That improves both supercharger response time and the engine's overall efficiency.

With the LS9, the numbers speak for themselves: 103 horsepower per liter displacement, with substantially higher specific torque than comparably sized engines from Ferrari and Lamborghini. Yet impressive output figures tell only part of the story.

The TVS supercharger's large displacement expands its effective range, building power more quickly at low rpm. Its four-lobe rotors spin at up to 15,000 rpm, or slightly more than twice the engine's rotation speed, to sustain its benefits at high engine speeds, when many superchargers lose their effectiveness. There's no high-rev power drop-off in the LS9.

Nor is there typical supercharger whine-the high-pitched, whizzing sound emanating from a supercharged engine as the rotors spin furiously. The four-lobe design helps lower noise radiating from the supercharger case as much as 10 decibels. Sound pressure is nearly identical whether or not the supercharger is generating boost.

The R2300 supercharger case and integrated intercooler have been tailored to the space available in the Corvette's engine bay. Despites its relatively large displacement, the supercharger sits neatly atop the 6.2L LS9 under a slight, see-through bulge in the ZR1's carbon-fiber hood. The air inlet and drive pulley are located at the front of the case, and the LS9's overall height is only slightly taller than the standard Corvette LS3 V-8.

Integrated Dual-Brick Air-to-Liquid Intercooler

An advanced intercooling system increases the 6.2L LS9's performance and extends its supercharger's benefits. The engine's charge cooler is integrated in the supercharger case just above the rotors, with two air-to-liquid cooling "bricks" that substantially lower the temperature of air used in the combustion process.

Intercoolers are familiar features on supercharged and turbocharged engines. Similar in concept to an engine's radiator, intercoolers cool the air pumped by the charging device into the cylinders. Cooler air is denser air, which means more oxygen in a given volume, resulting in optimal combustion and more power. Traditionally, intercoolers look like small radiators mounted somewhere outside the engine, with air fed into the engine through a plumbing network.

The LS9's intercooling system raises the bar in both packaging and efficiency. It uses two low-profile, aluminum tube-and-fin heat exchangers mounted longitudinally above the rotors in the supercharger case. Air pumped by the supercharger flows directly through these bricks to the intake ports on the cylinder heads. The bricks are cooled by their own coolant circuit, with a remote pump and 3.62-liter capacity heat exchanger mounted in front of the Corvette's radiator.

Bottom line: The temperature of air fed to the LS9's cylinder heads is reduced 140 degrees F (60 degrees C), substantially increasing the amount of oxygen available for the combustion process. The intercooler design also contributes to the supercharger's quiet operation. The cooling bricks help dampen sound radiating from the supercharger case, while ribs cast into the top of the intercooler housing add strength and reduce vibration.

Enhanced Gen IV Cylinder Block

The 6.2L Gen IV small block has been further refined for the LS9. It's cast from 319-T7 aluminum and fitted with cast-iron cylinder liners

Bulkheads in the LS9 engine block have been strengthened 20 percent by optimizing the size of the bulkhead "windows" to take advantage of material thickness in the bulkhead. This is additional improvement beyond a 20% gain obtained in the naturally aspirated 6.2L LS3 V-8 by increasing the radius of the hone over-travel fillets from three to 10 millimeters. The enlarged bulkhead windows also improve bay-to-bay breathing by managing airflow inside the engine more efficiently, thereby decreasing pumping loss, or reducing resistance to the pistons' downward movement.

Bulkheads are the structural elements that support the crank bearings. In the LS9, they accommodate six-bolt, cross-threaded main-bearing caps that limit crankshaft flex and stiffen the engine's structure. The caps are forged steel, fully machined on all surfaces and dowel aligned for precise fit and minimal vibration.

The cylinder liners are cast in the LS9 block and machined with a deck plate installed over the cylinder bores. The deck plate simulates the pressure and tiny dimensional changes that occur when the cylinder heads are bolted to the block. The process enhances assembly quality and fit, ensuring precise head sealing, improved piston ring sealing and peak performance as the engine accumulates miles.

Block enhancements initiated with the LS9 will be applied to all 6.2L Gen IV engine blocks, including those used for the new LSA in the 2009 Cadillac CTS-V, the LS3 Corvette V-8 and truck applications. While the Gen IV block shares its 90-degree cylinder angle and 4.4-inch bore centers with GM's original small block V-8, it applies design, casting and machining technologies that were unfathomable when the original was introduced in the 1950s.

The Gen IV block debuted in 2005 as the foundation for the 400-hp LS2 V-8 in the Chevrolet Corvette, Cadillac CTS-V and Pontiac GTO. It was developed with the latest math-based tools and data acquired in GM's racing programs, and it provides an exceptionally light, rigid foundation for an impressively smooth cam-in-block engine. Its deep-skirt design helps maximize strength and minimize vibration, and its aluminum construction reduces weight approximately 100 pounds compared to a conventional cast-iron cylinder block.

Forged-Aluminum Pistons with Oil-Spray Cooling

Superior piston design sets the tone all of the 6.2L LS9's internal components. The engineering objective? Lighter, stronger and smoother.

The pistons themselves are aluminum-not cast, but forged, for a high-performance combination of low mass, high strength and durability. These are considerably lighter than conventional aluminum pistons, which translates to less reciprocating mass inside the engine. Less mass means greater efficiency, high-rpm capability and a feeling of immediate response as the engine builds revs.

The combustion surface of the LS9 pistons, or the crown, lacks the valve-relief pockets typical on high-performance engines with relatively high-lift valves. Rather, the LS9 crown is sumped, with a saucer-shaped indent that dips gradually from the outer edge of the piston. This design promotes a thorough mixing of air and fuel and, with other durability enhancing features such as an anodized top ring groove, allows a 9.1:1 compression ratio: higher than a conventional supercharged or turbocharged engine, for improved combustion efficiency.

The anodized top ring groove reduces wear and accepts the heat generated during combustion between the top ring and its groove. To further reduce wear, the piston skirt is coated with a polymer material, which eliminates 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 wrist pins, which attach the piston to the connecting rod, were developed for maximum durability, with a large outer diameter and a tapered inner diameter. These pins "float" inside the rod bushing and 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. The benefit is less engine wear, improved durability and quieter operation.

Finally, the 6.2L LS9 represents the first line of small block V-8s equipped with oil-spray piston cooling. Eight oil-squirting jets in the engine block drench the underside of each piston and the surrounding cylinder wall with an extra layer of cooling, friction-reducing oil. The oil spray reduces piston temperature, promoting extreme output and long-term durability. The extra layer of oil on the cylinder walls and wristpin also dampens noise emanating from the pistons.

Lightweight Reciprocating Assembly with Titanium Connecting Rods

Careful analysis applied to the pistons extends to other reciprocating components inside the 6.2L LS9 V-8. Whenever possible, GM has trimmed mass, increased strength and reduced friction, enabling the LS9's high-rpm capability, improving overall performance and working to ensure durability.

Within the LS9's cylinder block spins a balanced, dropped-forged micro-alloy steel crankshaft with a nine-bolt flange to mount the flywheel. The nine-bolt pattern increases clamping strength compared to naturally aspirated 6.2L Gen IV V-8s, which use a six-bolt crank flange. A smaller-diameter ignition-timing reluctor wheel trims weight and ensures clearance to the pistons as they move in the bore. At the front end of the crank, the torsional damper is secured with a keyway and friction washer for an added element of security, given the LS9's exceptional torque.

Titanium connecting rods mate the crank with the pistons, for the ultimate combination of strength and light weight. The titanium rods weigh roughly 25 percent less than conventional iron or steel. They reduce pressure on both the rod-end bearings and main bearings, and allow the bearings to be optimally sized for the least amount of friction.

Refined Low Overlap Cam

A refined camshaft helps balance the 6.2L LS9's remarkable output with silky, tractable low-rev operation.

The camshaft operates the engine's valves, and its design is crucial to both power and smoothness. The torque enhancing benefits of the supercharger allowed GM engineers to develop a "softer," lower-lift camshaft for the LS9, compared to the typical high-rev, high-power exotic car engine. The LS9 cam delivers maximum lift of 14.3 mm for the intake valves and 14.2 mm for the exhaust valves. Moreover, the cam lobes are profiled to reduce the amount of time that both intake and exhaust valves are partially open at the same time. Valve overlap is reduced 27 percent compared to the track-bred 7.0L LS7 V-8 in the Corvette Z06. The result is smoother operation at low speeds, and particularly at idle. Idle quality improves 11 percent compared to the LS7.

High-Flow Rotacast Cylinder Heads with High Performance Valves

The 6.2L Supercharged LS9 cylinder heads are similar to those used on the naturally-aspirated 6.2L LS3 Corvette V-8, with enhancements for supercharged induction and maximum durability.

The LS9 heads feature a unique "wing'' cast into each intake port to promote a swirling motion that blends the pressurized air-fuel charge. The heads are also cast from a premium A356T6 alloy, which better manages the heat generated in a supercharged engine. A356T6 pays particular dividends in the thin bridge area between the intake and exhaust valves, where effective heat dissipation is crucial to both performance and long-term durability. Finally, the LS9 heads are rotacast. This process rotates the head mold as the molten alloy cools and essentially eliminates porosity, or microscopic pockets of air trapped in the casting. Rotacasting delivers a stronger part that helps maintain performance and structural integrity over the life of the engine.

Low-friction hydraulic roller lifters actuate the LS9's valves, with unique offset rocker arms for the intake valves. On the inlet rocker, the valve tip is offset six millimeters from the pushrod. This configuration allowed GM engineers to locate the intake port for a more direct air-fuel flow into the combustion chamber.

Intake valves measure 55 mm in diameter and are fabricated from titanium-chosen for its combination of strength, light weight and high-rpm potential. Perhaps more crucial to durability are the exhaust valves, which are typically the hottest part in the engine. Those in the LS9 measure 44.0 mm in diameter, and they're manufactured from a high-chromium steel alloy called SilChrome 1, with hollow, sodium-filled stems. At normal operating temperatures, the sodium inside the valve stem melts and becomes liquid. The liquid sodium improves conductivity, promoting heat transfer away from the valve face to the cooler end of the stem, where it more readily dissipates through the valve guide. This maintains a lower, more uniform valve temperature, reducing wear on the valve seat for a consistent seal between the valve and head over the life of the engine.

Given the LS9's pressurized induction, GM's engineers focused special attention on sealing. Head gaskets are extra-robust, four-layer stainless steel, and the 12 mm cylinder head bolts are hardened stainless. The 12 mm bolts increase head-gasket clamp strength (compared to 11 mm bolts on other small block engines), ensuring gasket sealing under the high combustions pressures generated by the LS9

Center-Feed Fuel System

The 6.2L LS9's fuel system was developed to deliver adequate fuel volume precisely consistently and quietly.

To ensure appropriate fueling in all conditions, from casual cruising to race track-type wide-open throttle, GM has equipped the LS9 with a dual- pressure fuel system. The system delivers 250 kPa (about 36 psi) at idle or low speeds. Yet the electronic throttle management system can almost instantaneously increase fuel pressure to 600 kPa for sustained high-speed operation or wide-open throttle. The dual-pressure system reacts according to throttle application, and presents several advantages. It limits the energy used by the fuel pump at low speeds, for maximum efficiency, and it reduces operational noise. It also ensures adequate fuel delivery when the LS9 demands its maximum flow rate of 58 grams per second.