||09-25-2009 12:54 PM
The mighty LSA supercharged V8.
Okay...first of all, nobody's actually confirmed that this engine will make it into the Z28 as-is...Even the LS3 got "altered" when it was transplanted into the Camaro. But it's a decent assumption to make that the LSA will be fitted to the car in some fashion...
So, I encourage you all to read the entire "Story", but I've highlighted the most important parts for those of you will less time or patience in Red
. And I added some extra points I've discovered through research in Blue
MORE IMAGES HERE:
GM Dyno Graph:
This thing makes over 350 lb/ft of torque at 1000rpms!!!
2010 "LSA" 6.2L V-8 SC (LSA)
2010 Model Year Summary
-Carryover Gen IV Small-Block V-8 for 2010 Cadillac CTS-V
-Gen VI Supercharger with Twin Four-Lobe Rotors
-Integrated Air-to-Liquid Intercooler
-Enhanced Gen IV Cylinder Block
-Hypereutectic Aluminum Pistons with Oil-Spray Cooling
-Lightweight Reciprocating Assembly
-Lower Lift, Low Overlap Cam
-High-Flow Rotacast Cylinder Heads
-Center-Feed Fuel System
-Direct-Mount Ignition Coils
-E67 Control Module
-Upgraded Oiling System
-Revised Accessory Drive
-High-Moly Cast Iron 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 model year for 2010 Cadillac CTS-V
The 556-hp 6.2L Supercharged Gen IV V-8 (RPO LSA) is installed longitudinally in the CTS-V, and available with GM's Hydra-Matic 6L90 six-speed automatic or the twin-disc Tremec TR6060 six-speed manual transmission. This engine is assembled in Silao, Mexico.
With 556 horsepower at 6100 rpm and 551 pound-feet or torque at 3800 rpm, certified by the Society of Automotive Engineers, the supercharged LSA V-8 is the most powerful production engine in Cadillac's 106-year history. It makes the CTS-V one of the fastest four-door automobiles in the world, with at least 23 percent more horsepower and 24 percent more torque than benchmark competitors such as the Audi RS4, BMW M3 and Mercedes-Benz C63 AMG, according to published figures.
As significantly, the LSA delivers an excellent balance of low-rev torque and high-rev horsepower, with the smooth, refined operation expected in a luxury brand. The new 6.2L Supercharged LSA takes Cadillac's tradition of outstanding power, performance and impressive refinement to new levels.
Gen VI Supercharger with Twin Four-Lobe Rotors
A state-of-the-art supercharger is key to the 6.2L LSA's remarkable performance. This Gen IV small-block V-8 is equipped with Eaton's Twin Vortices Series (TVS) supercharging technology, which represents the sixth generation of joint Eaton/GM supercharger development. The LSA supercharger displaces 1.9 liters and generates maximum boost pressure of 9.0 pounds per square inch (0.62 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 the supercharger's response time and the engine's overall efficiency.
With the TVS supercharger, the 6.2L LSA delivers nearly 1.5 horsepower per cubic inch of displacement and specific torque that's at least 18 percent higher than any of its primary competitors. Yet impressive output figures tell only part of the story. The supercharger's large displacement expands its effective range, building power more quickly at low rpm. Its four-lobe rotors spin at over 15,000 rpm, or about two and a half times 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 with the LSA.
Nor is there typical supercharger whine-the high-pitched, whizzing sound emanating from a supercharged engine as the rotors spin furiously. The four-lobe rotors help lower noise radiating from the supercharger case as much as 10 decibels, and sound pressure is nearly identical whether or not the supercharger is generating boost. During CTS-V development testing on Germany's 13-mile Nurburgring race course, onlookers were convinced that the LSA had no supercharger, even when it was running at wide-open throttle.
Integrated Air-to-Liquid Intercooler
An advanced intercooling system increases the 6.2L LSA's performance and extends its supercharger's benefits. The engine's charge cooler is integrated in the supercharger case just above the rotors, with a single air-to-liquid cooling "brick" 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 there is 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 LSA's intercooling system raises the bar in both packaging and efficiency. It uses a single aluminum tube-and-fin heat exchanger mounted above the rotors in the supercharger case. Air pumped by the supercharger flows directly through the brick and down to the intake ports on the cylinder heads. The intercooler brick is cooled by its own coolant circuit, with a remote pump and 3.02-liter reservoir mounted in front of the CTS-V's radiator.
Bottom line: The temperature of air fed to the LSA's cylinder heads is reduced 158 degrees F (70 degrees C), substantially increasing the amount of oxygen available for the combustion process. (This is more efficient cooling than the LS9, which only drops the air temperature by 140 degrees.)The intercooler design also contributes to the supercharger's quiet operation. The cooling brick helps 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 LSA. It's cast from 319-T5 aluminum and fitted with cast-iron cylinder liners
Bulkheads in the LSA 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. This is nearly identical to the LS9s block treatment! If there is any difference between the two, GM doesn't mention it.
Bulkheads are the structural elements that support the crank bearings. In the LSA, they accommodate six-bolt, cross-threaded main-bearing caps that limit crankshaft flex and stiffen the engine's structure. The caps are nodular iron, specified for its strength, rigidity and minimal vibration.
The cylinder liners are cast into the LSA block and machined with a deck plate installed over the cylinder bores. The deck plate simulates the pressure and minute dimensional changes that occur when the cylinder heads are bolted to the block. The process enhances assembly quality and fit, ensuring precise head sealing, perfect piston ring fit and peak performance as the engine accumulates miles.
Block enhancements initiated with the LSA will be applied to all 6.2L Gen IV engine blocks, including those used for the new LS9 in the 2009 Chevrolet Corvette ZR1, 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.
Hypereutectic Aluminum Pistons with Oil-Spray Cooling
Superior piston design sets the tone all of the 6.2L LSA's internal components. The engineering objective? Lighter, stronger and smoother.
The pistons themselves are aluminum-cast from a high-silicon alloy developed for its combination of strength and heat-management properties. Casting reduces noise-generating potential, compared to other high-performance piston materials such as forged aluminum, and is specified when NVH control is a priority. The hypereutectic pistons are also lighter than conventional steel, 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 LS9s pistons are made of forged aluminum. The key difference in material choice here, is the desire for refinement in the Cadillac application.
The combustion surface of the LSA pistons, or the top land, lacks the valve-relief pockets typical on high-performance engines with relatively high-lift valves. Rather, the LSA top lands are 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 along with other durability enhancing features, allows a 9.1:1 compression ratio: higher than a conventional supercharged or turbocharged engine, for improved combustion efficiency.
The durability enhancements include an anodized top land, which reduces wear and helps deflect heat generated during combustion away from the LSA's bottom end. To further reduce wear, the piston skirt is 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 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 while 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 LSA 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
Careful analysis applied to the pistons extends to other reciprocating parts inside the 6.2L LSA V-8. Whenever possible, GM has trimmed mass, increased strength and reduced friction, enabling the LSA's high-rpm capability (The LSA's redline is at 6200rpms, the LS9s is at 6500rpms), improving overall performance and working to ensure durability.
Within the LSA's cylinder block spins a balanced, dropped-forged steel crankshaft with an eight-bolt flange to mount the flywheel. (The LS9 has a 9-bolt pattern). The eight-bolt pattern increases clamping strength compared to naturally aspirated 6.2L Gen IV V-8s, which use a six-bolt crank flange. 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 LSA's exceptional torque. The crank design reduces noise a single decibel-small in itself, but significant to overall refinement in a true high-performance luxury sedan.
Forged powder-metal connecting rods mate the crank with the pistons. These rods are forged under extreme pressure from alloy metals reduced to powder, rather the melted to liquid, for a balance of low mass and high strength. They reduce pressure on both the rod-end bearings and main bearings, compared to conventional rods, and allow the bearings to be optimally sized for the least amount of friction.
Lower Lift, Low Overlap Cam
A refined camshaft helps balance the 6.2L LSA'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 LSA, compared to the typical high-rev, high-power super-sedan engine. The LSA cam delivers maximum lift of 12.2 mm for both the intake and 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 compared the previous, LS2-powered CTS-V, despite the substantial increase in output. The result is smoother operation at low speeds, and particularly at idle.
The cam design also reduces operating noise compared to the naturally aspirated 6.2L Corvette LS-3 V-8 by one decibel. While the change might not seem significant by itself, it combines with similar incremental improvements through the LSA that reduce interior noise in the 2009 CTS-V substantially compared its predecessor