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Figured since its powered by a 60V6, I'd post about it... Check out the pic at the bottom and notice the slight rotation of the engine. I'll also include a pic of the tranny...
Originally posted by GM Media
GMC’s all-new 2007 Acadia is powered by GM’s 3.6L V-6 with variable valve timing (VVT) and backed by a new Hydra-Matic 6T75 six-speed automatic transmission. It is a powertrain combination designed to optimize power, fuel economy and emissions performance while delivering a smooth and responsive driving experience.
The 3.6L V-6 VVT is a dual-overhead camshaft engine jointly developed at GM technical centers in Australia , Germany , Sweden and North America . It uses full four-cam phasing, rapid data processing and torque-based engine management to optimize power, fuel efficiency and emissions performance. In the Acadia , the engine produces 267 horsepower (199 kW) and 247 lb.-ft. of torque (335 Nm).*
The four-cam phasing operation of the variable valve timing system ensures linear delivery of torque across the rpm band, while features such as electronic throttle control deliver crisp, immediate response and feedback. The engine uses electro-hydraulic vane-type phasers to rotate the camshafts relative to the cam-drive sprockets, allowing infinitely variable combinations over a range of 50 degrees.
The adoption of fully variable valve timing for both the intake and exhaust valves enables outstanding performance, fuel economy and emissions. The four-cam variable valve timing is a key element in the V-6’s control strategy, which gives the engine a wide-ranging flexibility. For example, 90 percent of the 3.6L V-6’s peak torque is available across a broad operating range, from approximately 1,600 rpm to 5,800 rpm.
Additional engine features include:
Dual-stage variable intake manifold (VIM) . The VIM incorporates a switch in the manifold that automatically changes the plenum volume available for resonance tuning of the inlet flow path.
Micro-hybrid engine control unit (ECU). The V-6’s ECU represents the latest in engine-management hardware, as well as the software that dictates every aspect of engine operation.
Isolated cam covers. The covers incorporate an isolated gasket around the cover perimeter and radial lip seals at the tubes through which each spark is inserted.
Piston-cooling oil-jet assemblies. Three pressure-activated oil-jet assemblies are located in the block. Each holds a pair of oil squirters that douse the underside of the piston and the surrounding cylinder wall with cooling oil. The benefit is piston temperatures resulting in more engine power.
Polymer coating on the piston skirts . A low-friction coating on the pistons’ skirts helps the pistons track more smoothly and quietly in the bores.
Low-noise oil pump design. The result of a specialized analysis of pump flow, the 3.6L oil pump prevents noise caused by oil aeration.
Forged steel crankshaft . For optimum strength, the forged crankshaft delivers additional stiffness for better noise, vibration and harshness performance; and provides an extra degree of robustness.
Coil-on-plug ignition system. Individual ignition coils mounted above each cylinder provide more precise and more accurate spark, which supports a more complete, more efficient burn of the air/fuel mixture.
The aluminum-intensive 3.6L V-6 VVT also is designed to deliver its performance with smoothness, quietness and durability. The camshaft chain drives are nearly silent during operation. Other elements, including the cam covers, intake manifold and direct-mounted accessories, are designed to reduce or eliminate conventional points of noise, vibration and harshness. A long operating life is driven by heavy duty and special components, such as a forged steel crankshaft, polymer-coated pistons and oil jets that drench the bottom of the pistons in cooling, lubricating oil.
All engines in the GM global V-6 family share traits that include a lightweight aluminum cylinder block with iron cylinder sleeves, an aluminum structural oil pan and high-flow aluminum cylinder heads with four valves per cylinder.
Fuel-saving six-speed automatic
A new Hydra-Matic 6T75 electronically controlled six-speed automatic transmission backs the 3.6L V-6 VVT. It is an advanced transmission with clutch-to-clutch shift operation for front- and all-wheel drive vehicles. Among the advantages of a six-speed automatic is reduced engine rpm on the highway. Lower engine rpm can bolster fuel economy because less fuel is used – Acadia ’s fuel economy is estimated at 17 mpg in city driving and 25 mpg on the highway with FWD models and an estimated 17 and 24 mpg with AWD models. A lower-rpm cruising speed also enhances smoothness and reduces noise heard in the vehicle’s cabin.
Clutch-to-clutch operation allows for reduced complexity and compact packaging. A wide, 6.04:1 overall ratio helps the transmission deliver both performance and fuel economy, enabling up to 8 percent improved performance and up to 4 percent improved fuel economy when compared with current front-wheel drive four-speed automatics. The 6T75 uses a “steep” 4.48:1 first gear, to deliver exceptional launch feel, and a 0.74:1 overdrive sixth gear – the “tall” overdrive gear lowers rpm at high speeds, reducing noise, vibration and harshness. Fifth gear is 1:1 direct drive.
The 6T75’s innovative clutch-to-clutch operation is designed for improved shift feel and efficiency. All shifts except 1-2 (the transmission “free wheels” in first and second gears) feature clutch-to-clutch operation. This is achieved through three planetary gears, with three stationary clutches and two rotating clutches. It’s a simple, less complex design that enables the packaging of six gears in the space of a four-speed automatic.
Also, the 6T75 offers the capability of Electronic Range Select (ERS), which allows the driver to use tap-up/tap-down shifting to select the desired gear range for specific road conditions. An electro-hydraulic control module (TEHCM) is mounted inside the transmission, reducing vehicle complexity. Similar to the control system used in some Hydra-Matic rear-wheel drive transmissions, the TEHCM offers improved quality through its hard-wired connections. The unit is located entirely within the transmission and operates while bathed in transmission fluid. Locating the controller internally facilitates the modular design and assembly strategy while also shielding the unit from the outside environment.
*Preliminary, pending SAE certification. A new voluntary power and torque certification procedure developed by the SAE Engine Test Code committee was approved March 31, 2005 . This procedure (J2723) ensures fair, accurate ratings for horsepower and torque by allowing manufacturers to certify their engines through third-party witness testing. GM was the first auto manufacturer to begin using the procedure and expects to use it for all newly rated engines in the future.
The 3.6L V-6 VVT is a dual-overhead camshaft engine jointly developed at GM technical centers in Australia , Germany , Sweden and North America . It uses full four-cam phasing, rapid data processing and torque-based engine management to optimize power, fuel efficiency and emissions performance. In the Acadia , the engine produces 267 horsepower (199 kW) and 247 lb.-ft. of torque (335 Nm).*
The four-cam phasing operation of the variable valve timing system ensures linear delivery of torque across the rpm band, while features such as electronic throttle control deliver crisp, immediate response and feedback. The engine uses electro-hydraulic vane-type phasers to rotate the camshafts relative to the cam-drive sprockets, allowing infinitely variable combinations over a range of 50 degrees.
The adoption of fully variable valve timing for both the intake and exhaust valves enables outstanding performance, fuel economy and emissions. The four-cam variable valve timing is a key element in the V-6’s control strategy, which gives the engine a wide-ranging flexibility. For example, 90 percent of the 3.6L V-6’s peak torque is available across a broad operating range, from approximately 1,600 rpm to 5,800 rpm.
Additional engine features include:
Dual-stage variable intake manifold (VIM) . The VIM incorporates a switch in the manifold that automatically changes the plenum volume available for resonance tuning of the inlet flow path.
Micro-hybrid engine control unit (ECU). The V-6’s ECU represents the latest in engine-management hardware, as well as the software that dictates every aspect of engine operation.
Isolated cam covers. The covers incorporate an isolated gasket around the cover perimeter and radial lip seals at the tubes through which each spark is inserted.
Piston-cooling oil-jet assemblies. Three pressure-activated oil-jet assemblies are located in the block. Each holds a pair of oil squirters that douse the underside of the piston and the surrounding cylinder wall with cooling oil. The benefit is piston temperatures resulting in more engine power.
Polymer coating on the piston skirts . A low-friction coating on the pistons’ skirts helps the pistons track more smoothly and quietly in the bores.
Low-noise oil pump design. The result of a specialized analysis of pump flow, the 3.6L oil pump prevents noise caused by oil aeration.
Forged steel crankshaft . For optimum strength, the forged crankshaft delivers additional stiffness for better noise, vibration and harshness performance; and provides an extra degree of robustness.
Coil-on-plug ignition system. Individual ignition coils mounted above each cylinder provide more precise and more accurate spark, which supports a more complete, more efficient burn of the air/fuel mixture.
The aluminum-intensive 3.6L V-6 VVT also is designed to deliver its performance with smoothness, quietness and durability. The camshaft chain drives are nearly silent during operation. Other elements, including the cam covers, intake manifold and direct-mounted accessories, are designed to reduce or eliminate conventional points of noise, vibration and harshness. A long operating life is driven by heavy duty and special components, such as a forged steel crankshaft, polymer-coated pistons and oil jets that drench the bottom of the pistons in cooling, lubricating oil.
All engines in the GM global V-6 family share traits that include a lightweight aluminum cylinder block with iron cylinder sleeves, an aluminum structural oil pan and high-flow aluminum cylinder heads with four valves per cylinder.
Fuel-saving six-speed automatic
A new Hydra-Matic 6T75 electronically controlled six-speed automatic transmission backs the 3.6L V-6 VVT. It is an advanced transmission with clutch-to-clutch shift operation for front- and all-wheel drive vehicles. Among the advantages of a six-speed automatic is reduced engine rpm on the highway. Lower engine rpm can bolster fuel economy because less fuel is used – Acadia ’s fuel economy is estimated at 17 mpg in city driving and 25 mpg on the highway with FWD models and an estimated 17 and 24 mpg with AWD models. A lower-rpm cruising speed also enhances smoothness and reduces noise heard in the vehicle’s cabin.
Clutch-to-clutch operation allows for reduced complexity and compact packaging. A wide, 6.04:1 overall ratio helps the transmission deliver both performance and fuel economy, enabling up to 8 percent improved performance and up to 4 percent improved fuel economy when compared with current front-wheel drive four-speed automatics. The 6T75 uses a “steep” 4.48:1 first gear, to deliver exceptional launch feel, and a 0.74:1 overdrive sixth gear – the “tall” overdrive gear lowers rpm at high speeds, reducing noise, vibration and harshness. Fifth gear is 1:1 direct drive.
The 6T75’s innovative clutch-to-clutch operation is designed for improved shift feel and efficiency. All shifts except 1-2 (the transmission “free wheels” in first and second gears) feature clutch-to-clutch operation. This is achieved through three planetary gears, with three stationary clutches and two rotating clutches. It’s a simple, less complex design that enables the packaging of six gears in the space of a four-speed automatic.
Also, the 6T75 offers the capability of Electronic Range Select (ERS), which allows the driver to use tap-up/tap-down shifting to select the desired gear range for specific road conditions. An electro-hydraulic control module (TEHCM) is mounted inside the transmission, reducing vehicle complexity. Similar to the control system used in some Hydra-Matic rear-wheel drive transmissions, the TEHCM offers improved quality through its hard-wired connections. The unit is located entirely within the transmission and operates while bathed in transmission fluid. Locating the controller internally facilitates the modular design and assembly strategy while also shielding the unit from the outside environment.
*Preliminary, pending SAE certification. A new voluntary power and torque certification procedure developed by the SAE Engine Test Code committee was approved March 31, 2005 . This procedure (J2723) ensures fair, accurate ratings for horsepower and torque by allowing manufacturers to certify their engines through third-party witness testing. GM was the first auto manufacturer to begin using the procedure and expects to use it for all newly rated engines in the future.
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