Working closely with GM’s new Performance Division, GM Powertrain engineers have developed the 5.7L LS6 V-8 for application in Cadillac’s highly successful CTS sedan. With GM’s most powerful passenger-car engine (and one of the world’s best sports car engines), the resulting Cadillac CTS-V delivers exceptional performance that meets or beats the best luxury-performance sedans from Europe and Japan by virtually any measure.
The CTS-V LS6 has the incredible low-end grunt, the same broad powerband and the efficient, high-rev breathing that driving enthusiasts admire in the Corvette Z06.
“The CTS-V engine is a Corvette LS6 in nearly every aspect except for the exhaust manifolds, the oil pan and the accessory drive,’’ said Dave Muscaro, assistant chief engineer for the LS1 and LS6 V-8s. “Yet Corvette is a pure sports car, with the cammy, tingling idle sports car drivers expect. The CTS-V is a luxury sedan – a Cadillac – that just happens to go like stink. Refinement is prerequisite. To address this discrepancy, development engineers created new engine mounts – called ‘focus mounts’ – for the CTS-V.”
Engine mounts serve two purposes: They hold the engine in the vehicle, and they isolate some of the engine’s inherent vibration from be transmitted through the frame or vehicle platform. Most vehicles, including the Corvette, have vibration-dampening material on the platform side of the engine mounts. The engine bolts directly to the mounts, and the mounts bolt to the frame with some type of isolating material or device. After analyzing the LS1’s center of gravity and its placement in the CTS-V platform, the development team came up with an elegant alternative. The CTS-V’s focus mounts move the dampeners – in this case, liquid-filled rubber isolators – to the engine side of the mounts. Dampening occurs closer to the LS6’s center of gravity, before engine vibration travels down the mounts to the platform. The result is vibration control appropriate for a Cadillac, with a smoother idle that barely hints at what the CTS-V has in store when the driver slams the gas pedal to the floor.
The LS6 also required a few packaging adjustments for its move from a sports car to a four-door sedan. The air box, air filter and snorkel leading to the throttle body were reworked to fit the CTS engine bay, with the new CTS-V induction plumbing drawing air nearly as efficiently as the Corvette.
The LS1’s cast nodular iron exhaust manifolds were redesigned to fit the CTS platform architecture and, at the bottom of the engine, the LS6 oil pan was reshaped to accommodate the CTS’ front suspension and steering. Like the Corvette (and unlike the Pontiac GTO), the CTS-V oil pan has a rear sump, similar to the pan of the Chevrolet Camaro and Pontiac Firebird.
Finally, the LS6’s accessory drive belt was rerouted for the CTS-V. From the front view, accessories such as the alternator and power steering pump are positioned similarly to those on the Pontiac GTO LS1, so the CTS-V belt follows a similar route. Yet viewed from the top, the belt tracks 20 mm closer to the block, at the same depth as the Corvette LS6 belt.