New engine family, 6T35 transmission balance power, efficiency and refinement
DETROIT – 06.24.2015 – The 2016 Chevrolet Cruze is powered by General Motors’ new, global family of Ecotec small-displacement engines, featuring a modular architecture that is easier to build and adaptable to global markets, while offering customers segment-challenging efficiency, refinement and durability.
In North America, the Cruze is offered with a new Ecotec 1.4L turbocharged engine that features direct injection to help offer a GM-estimated 40 mpg on the highway with an available six-speed automatic transmission. Standard stop/start technology contributes to efficiency in stop-and-go driving.
The new 1.4L turbo is SAE-certified at 113 kW (153 hp) and 240 Nm of torque (177 lb-ft), using regular unleaded fuel (RON 91). It will be offered in additional markets, along with a 1.5L naturally aspirated variant rated at an estimated at 84 kW (113 hp) and 146 Nm of torque (108 lb-ft). The 1.5L will be matched with a five-speed manual transmission.
“The new Ecotec family is a globally designed and manufactured engine designed to offer class-leading performance, efficiency and refinement in a wide variety of applications around the world,” said Dan Nicholson, vice president, GM Global Powertrain. “Each variant is designed for a specific application or local market, but all share design, performance and refinement traits that make the new architecture one of the most adaptable in the industry.”
The new Ecotec 1.4L turbo is matched with a standard six-speed manual or available with GM’s new Hydra-Matic 6T35 six-speed automatic transmission. It offers the strength of the larger 6T40 transmission in a smaller, lighter package that enhances efficiency in the compact Chevy Cruze.
Chevy will add a new clean diesel engine to the lineup in 2017, featuring a B20-capable 1.6L diesel already proven in Europe and other global markets.
“The current Chevy Cruze diesel has garnered a loyal following among customers seeking strong, clean and efficient diesel,” said Nicholson. “The next Cruze diesel will take those attributes to the next level with the very latest technology, offering what we expect will be the premier small-car diesel package in North America. It affirms GM’s commitment to offer diesel engines as an alternative propulsion choice for cars in North America and specifically targets the German dominance in the segment.”
More information about the next Cruze diesel will be available closer to the start of production.
The new Ecotec small-displacement engine family featured in the Cruze represents a clean-sheet design and engineering process, leveraging the diverse experience of GM’s global resources. Modularity in parts – such as four-cylinder and three-cylinder blocks – that share bore spacing, bore diameter, liners and other dimensions, reduces complexity and enhances value.
The new engines feature an aluminum cylinder block and head, which helps reduce the Cruze’s overall mass to enhance performance and efficiency. They also feature an integrated aluminum cylinder head/exhaust manifold, which further reduces weight – an attribute that contributes to increased vehicle efficiency and a more favorable front-to-rear weight balance, for a more responsive driving experience.
Additional engine features:
- Aluminum bedplate on the engine block enhances strength and refinement
- Variable-flow oil pump enhances efficiency
- Piston-cooling oil jets contribute to optimal performance, efficiency and refinement
- Dual-overhead-cam cylinder head with integrated exhaust manifold saves weight to enhance performance and efficiency
- Premium inverted-tooth camshaft drive chain contributes to segment-challenging levels of refinement and low noise.
Computer simulation and modeling were instrumental in developing the new engine family. GM’s engineers at powertrain centers around the globe were able to design and test parts virtually and immediately share the results with their colleagues.
In addition to designing the engines’ basic components electronically, friction, temperature, emissions, efficiency and other performance attributes were modeled and simulated multiple times to make the most of performance before the first physical components were produced. Modeling also helped cylinder block design and other components with structural and acoustic considerations.
“By doing the majority of the development with math data, the time to design, validate and bring to market an all-new engine family was greatly reduced,” said Tom Sutter, Ecotec global chief engineer.
The engines’ calibration and performance characteristics vary among markets, but all variants were tested under GM’s strict regimen regardless of their application. It’s one of the toughest sets of standards in the industry and included a battery of around-the-clock performance and durability trials such as:
- Running test engines continuously for more than 2,000 hours at 5,200 rpm – the equivalent of 12 straight weeks at wide-open-throttle
- Cycling engines for 400 straight hours (more than 16 days) between peak horsepower and peak torque rpm levels – a torturous test that pushes rotating parts such as the crankshaft and connecting rods to their limits
- Running engines on a tilt stand – a hydraulically actuated dynamometer that tilts the engine during operation to simulate driving on steep grades or high-speed cornering. That helps ensure the oiling system maintains full pressure during extreme driving conditions
- Cold- and heat-soak tests that ensure the engine will start and operate normally in temperatures as low as -40 degrees C (-40 F) and as high as 104 degrees C (219 F)
- Testing in an acoustic laboratory to measure engine sound frequency, ensuring production-spec components work harmoniously to produce low vibration and a pleasing engine sound.
Lightweight and durable foundation
A lightweight, high-pressure die-cast aluminum block is the engines’ foundation, matched with an aluminum bedplate that enhances strength and helps reduce vibration. The high-pressure casting method produces a more dimensionally accurate block that requires fewer machining operations than conventional sand-cast blocks.
For structural stiffness, the block has cast-in-place iron cylinder liners. The bedplate bulkheads also contain cast-in, nodular iron inserts for localized structural stiffness. A die-cast aluminum oil pan contributes additional structural strength.
Each engine features 74 mm (2.9-inch) cylinder bores and comparatively long piston stroke lengths that contribute to their strong torque. The 1.4L has an 81.3 mm (3.2-inch) stroke and the 1.5L version has an 86.6mm (3.4-inch) stroke.
Bay-to-bay breathing, which enhances performance through reduced windage in the crankcase, is enabled through holes cast in the top of the bulkheads and through passages cast where the block and bedplate meet. Cast passages for oil and blow-by management and a 4 mm wall thickness combine to reduce the overall weight of the block assembly, enhancing vehicle performance and efficiency.
Additional engine features:
- A durable steel crankshaft is used with the Ecotec 1.4L turbo and Ecotec 1.5L for strength and reduced engine vibration
- Powder-metal steel connecting rods and hypereutectic-alloy aluminum pistons that are tough and contribute to quietness. They are used with low-tension rings that reduce friction, which contributes to greater efficiency
- A variable-flow oiling system helps maximize fuel efficiency, contributing to GM’s estimated 40 mpg highway. The crankshaft-driven oil pump matches the oil supply to the engine load, changing its capacity based on the engine’s demand for oil – eliminating energy wasted to pump oil that is not required for proper engine operation
- Piston-cooling oil jets minimize piston temperatures – helping to optimize performance, refinement, efficiency and emissions.
The cylinder head has a water-cooled exhaust manifold integrated within the aluminum casting. Its single-piece design promotes quicker engine warm-up, which contributes to better emissions performance. It also enhances durability by eliminating the need for gasket sealing around the exhaust ports, as well as offering under-hood packaging advantages.
Dual overhead camshafts, operating four valves per cylinder with low-friction, hydraulic roller finger followers, are hollow in sections to save weight, and are driven by a timing chain with automatic hydraulic tensioning. Aluminum cam phasers enable variable timing for the opening and closing of the inlet and exhaust valves, making the most of fuel consumption and performance under a wide variety of engine load conditions.
Along with performance and efficiency, the 2016 Cruze’s new Ecotec engines deliver excellent refinement, with low vibration and noise levels.
Engineers targeted every aspect of the architecture, reciprocating components, fuel system and engine management functions in the quest for world-class smoothness and quietness. It all starts with the all-aluminum architecture, which is acoustically designed to reduce airborne and structure-borne operating noise.
Additional features that contribute to the engines’ refinement include:
- The camshaft drive-chain is optimized for low sound levels through an inverted-tooth design. The entire chain architecture, including its tensioning, wrap and guides, is designed for reduced overall noise radiation and the elimination of any perceived abnormal sounds
- The integration of a stamped steel sump at the bottom of the aluminum oil pan also reduces noise
- The front-end accessory drive features an overriding alternator coupler to remove the effect of crankshaft oscillations. In addition to refinement benefits, it also reduces tension to reduce friction levels and improve efficiency
- Acoustically optimized covers for the top and front of the engine
- Crankshaft isolation with iron main bearing inserts.
The Ecotec 1.4L will be assembled in Flint, Mich. with locally and globally sourced parts. GM’s engine facility in Toluca, Mexico will also build the 1.4L, as well as the Ecotec 1.5L.
New 6T35 six-speed automatic transmission
The new Hydra-Matic 6T35 six-speed automatic transmission offered with the Cruze’s new 1.4L turbo engine expands GM’s multispeed transmission family for transverse powertrain systems.
It is a higher-capacity version of the current 6T30 transmission, offering comparable torque capacity of the larger 6T40, but in a smaller, 11-kg (24 lbs) lighter package contributing to the Cruze’s reduced overall weight and enhancing the front-to-rear weight balance.
Shared traits between GM’s six-speed automatic transmissions also reduce complexity, size and mass, including clutch-to-clutch operation that enables the six-speed to be packaged into approximately the same space of a four-speed automatic.
A wide ratio spread enables brisk acceleration from a stop, while the overdriven sixth gear – it “turns” slower than engine speed – keeps the engine speed lower on the highway, reducing engine friction losses, optimizing efficiency and contributing to a quieter ride.
The 6T35 also features Gen 3 upgrades implemented to enhance efficiency. The pump, for example, has been moved off-axis, which allows better sealing of the torque converter, reducing pump flow demands to enhance fuel economy. Additionally, the pump is now a binary vane-type, which allows lower power consumption during times of lower flow demands and at higher engine speeds. An accumulator is added to the transmission to accommodate the stop/start system.
The 6T35 will be built at GM’s transmission facility in Toledo, Ohio.
Cruze models equipped with the 1.4L turbocharged engine are offered with the M32-code six-speed manual transmission, a high-capacity gearbox for transverse configurations. A wide, 7:1 overall ratio balances acceleration and efficiency.
The M32 has a premium three-shaft design with synchronizers for all gears, including reverse. First and second gears feature triple-cone synchronizers and double-cone synchronizers are used on third and fourth gears. An external shift system enhances the high-quality feel of the transmission with short, precise shifts, as well as a vibration absorber.
Models equipped with the 1.5L engine are offered with a five-speed manual transmission – a compact, lightweight transmission featuring a two-shaft design and premium features such as full synchronization on the forward gears and semi-synchronized engagement for reverse. Hydraulic clutch actuation and a cable-type shifting system enable light, easy and smooth shifting.