The all-new 2008 Cadillac CTS features a sophisticated chassis, an enhanced engine and transmission lineup and all-wheel drive to push the new CTS further in all directions.  Together they offer impressive performance, enhanced ride quality, quietness and safety. The new 3.6L direct-injected V-6 VVT engine delivers 311 hp (229 kW*) and 374 Nm of torque at 5200 rpm. Like the rest of the engine lineup, this new power plant combines power with smoothness, efficiency and technical sophistication.

“The new 3.6-liter Direct Injection engine is our highest specific-output V-6 and very fuel-efficient,” said Dr. Uwe Grebe, GM Powertrain’s executive director of advanced engineering. “It’s the latest example of our strategy to continue to reduce emissions and improve fuel economy while enhancing performance.”

The standard engine is a 2.8L V-6, with a rating of 211 hp (155 kW) and 246 Nm of torque at 3600 rpm.  The 2.8 V-6 VVT engine will be available only on rear-wheel-drive models. The 2.8L is an all-aluminum, 60-degree DOHC, four-valve-per-cylinder engine.

In addition, a 3.6L V-6 VVT engine, which produces 266 hp (196 kW)* and 343 Nm of torque at 3100 rpm, is available in some global regions.  It is offered in both rear- and all-wheel-drive layouts.

For the first time, the Cadillac CTS will be available in both rear- and all-wheel-drive configurations. Additionally, the transmission lineup now consists exclusively of six-speed units – an Aisin six-speed manual or – new for CTS – a Hydra-Matic 6L50 six-speed automatic. All models have been engineered to achieve nearly 50/50 weight balance, a key element of the CTS’ exceptional ride and handling.

Direct-Injection technology

The 3.6L Direct Injection engine is the premium engine option for the 2008 Cadillac CTS. This technology on the 3.6L VVT engine contributes greatly to a 15-percent increase in horsepower; 8-percent increase in torque, and 3-percent improvement in fuel consumption. Additionally, the application of direct injection reduces cold-start hydrocarbon emissions by 25 percent and it is designed to operate with regular unleaded gasoline. The engine also helps the CTS achieve zero to 100 km/h performance of 6.3 seconds and a top speed of 249 km/h (electronically limited).

Gasoline direct injection differs from the fuel delivery process of a conventional fuel injected engine by delivering fuel directly into the combustion chamber, where it is mixed with air drawn in the chamber; the conventional design mixes the air and fuel prior to delivery into the combustion chamber. The advantage is improved fuel control and a more complete burn, which generally requires less fuel than a conventionally injected engine of the same size and configuration.

With the 3.6L direct injection engine, fuel is introduced directly to the cylinder during the intake stroke. As the piston approaches top-dead center, the mixture is ignited by the spark plug. The fuel injectors are located beneath the intake ports, as the intake ports only transfer air. Direct injection also permits a slightly higher compression ratio than if the fuel were delivered with conventional fuel injection. The result is better fuel consumption at part and full throttle. The engine uses conventional spark plugs similar to other high-feature V-6 engines.

A high-pressure, returnless fuel system is employed. It features a high-strength stainless steel fuel line that feeds a variable-pressure fuel rail. Direct injection requires higher fuel pressure than conventional fuel injected engines and an engine-driven high-pressure fuel pump is used to supply up to 1,740 psi (120 bar) of pressure. The system regulates lower fuel pressure at idle – approximately 508 psi (35 bar) and higher pressure at wide-open throttle. The exhaust cam-driven high-pressure pump works in conjunction with a conventional fuel tank-mounted supply pump.

Direct injection’s fuel delivery enables very efficient combustion to help reduce emissions, particularly on cold starts – the time when most tailpipe emissions are typically created. Also, direct injection permits a higher compression ratio – 11.3:1 in the case of the 3.6L – which has a positive influence on fuel economy.

3.6L Direct Injection VVT

The 3.6L Direct Injection VVT engine is based on a sophisticated 60-degree dual overhead cam (DOHC) V-6 design. It is the latest member of a growing family of V-6 engines developed for applications around the world, drawing on the best practices and creative expertise of technical experts in Australia, Germany, North Americaand Sweden.

Features found on the 3.6-liter VVT DI include:

• Aluminum engine block and cylinder heads
• Dual overhead cams with four valves per cylinder and silent chain primary drive
• High-pressure, engine-driven fuel pump
• Advanced multi-outlet fuel injectors developed to withstand high pressure and heat
• Stainless steel, variable pressure fuel rail
• Four-cam phasing (VVT – see description below)
• 11.3:1 compression ratio
• Aluminum pistons with floating wrist pins and oil squirters
• Polymer coated piston skirts
• Forged steel crankshaft
• Sinter-forged connecting rods
• Structural cast-aluminum oil pan with steel baffles
• Electronic throttle control with integrated cruise control
• Coil-on-plug ignition
• Advanced direct injection capable engine control module (ECM)
• Optimized exhaust manifolds with close-coupled catalytic converters
• Fully isolated composite camshaft covers
• Outstanding noise, vibration and harshness control
• Maximum durability with minimum maintenance
• Common manufacturing practices for efficiency and exceptional quality

Four-cam phasing

The 3.6L Direct Injection VVT employs four-cam phasing to change the timing of valve operation as operating conditions such as rpm and engine load vary. The result is linear delivery of torque, with near-peak levels over a broad rpm range, and high specific output (maximum horsepower per liter of displacement) without sacrificing overall engine response and driveability. When combined, direct injection and cam phasing technologies result in an unmatched combination of power, efficiency and low emissions in gasoline V-6 engines.

Camphasing pays big dividends in reducing exhaust emissions by optimizing exhaust valve overlap and eliminating the need for a separate exhaust gas recirculation (EGR) system.

By closing the exhaust valves late at appropriate times, the cam phasers allow the engine to draw the desired amount of exhaust gas back into the combustion chamber, reducing unburned hydrocarbon emissions. The return of exhaust gases also decreases peak temperatures, which contributes to the reduction of oxides of nitrogen (NOx) emissions. In tandem with the dramatic 25-percent reduction in cold-start hydrocarbon emissions brought on by direct injection, the 3.6L Direct Injection VVT V-6 surpasses all emissions mandates, and does so without complex, weight-increasing emissions control systems such as EGR and air injection reaction (AIR).

Diesel engine for 2009

A state-of-the-art, direct-injected turbo-diesel engine will be available in calendar year 2009.  The V-6diesel will have a displacement of 2.9 liters, an output of 250 hp (184 kW) and a torque of 550 Nm beginning at 2000 rpm.

Six-speed transmissions deliver balance of performance and fuel economy

All Cadillac CTS powertrains will be offered with a six-speed transmission. The Aisin six-speed manual is the standard transmission in the CTS. It is fully synchronized (including reverse) with a single overdrive. This allows for lower propshaft speeds and improves engine noise, vibration and harshness. A short-throw shifter is designed for improved precision and enhanced driver feel.

The Aisin six-speed manual is engineered to handle the torque of the CTS’ powerful V-6 engines, with features that include low shift effort, closer ratios – for a more performance-oriented feel – and quiet operation. It also features a tailset design that uses a long input shaft supported by a short output shaft. It’s a configuration that is the converse of conventional two-axis manual transmissions that incorporate a “headset” design.

The Hydra-Matic 6L50 six-speed automatic transmission is designed to decrease engine rpm and enhance overall fuel economy. It features design traits that enable reduced complexity, size and mass, including clutch-to-clutch operation that allows the six forward gear sets to be packaged into approximately the size of a four-speed automatic. The 6L50 has an overall 6.04:1 ratio, which contributes significantly to its balance of performance and fuel economy.

The 6L50 also incorporates a host of advanced driving enhancement features, including Performance Algorithm Liftfoot (PAL) and Driver Shift Control (DSC). PAL lets the electronic transmission controller override the automatic gear selection during closed-throttle, high-lateral acceleration maneuvers, while DSC allows the driver to sequentially shift gears manually via the gearshift lever.

On models with the new all-wheel-drive system, the 6L50 will be equipped with a new active transfer case that automatically transfers torque from the rear to the front of the vehicle – up to 100 percent of the torque in certain situations – for optimal traction, safety and performance. The rate of torque split between the front wheels and rear wheels is infinitely variable and is determined by the system’s electronic controller. A limited-slip differential also is standard in CTS models sold in Europe.