TURBOCHARGER FORCE-FEEDS THE COBALT SS 2.0L ECOTEC ENGINE FOR 260 HP (194 kW)

DETROIT – The Cobalt SS is powered by a turbocharged and intercooled 2.0L Ecotec DI engine that delivers 260 horsepower (194 kW) and 260 lb.-ft. of torque (353 Nm) with the standard five-speed manual transmission.

“Chevrolets are about fun and the SS models are the most fun of all,” said John Heinricy, GM Performance Division executive. “With the Cobalt SS, fun is balanced with a serious degree of capability, on both the street and racetrack.”

Features such as “no-lift shift” and other driver-selectable performance modes help the Cobalt SS achieve 0-60 mph performance in approximately 5.7 seconds and cover the quarter-mile in approximately 14.1 seconds, with minimal torque steer. The top speed is more than 160 mph.

2.0L Ecotec DI turbo engine details

The Cobalt SS’s Ecotec 2.0L turbo engine is the same that powers the recently introduced HHR SS. It produces 2.1 horsepower per cubic inch of displacement (130 hp / 97 kW per liter) and is the most powerful engine in the Ecotec family. Gasoline direct-injection technology helps the engine produce more power while maintaining the lower fuel consumption of a small displacement port-injected engine.

With direct injection, fuel is delivered directly to the combustion chamber to create a more complete burn of the air/fuel mixture. Less fuel is required to produce the equivalent horsepower, especially at normal cruising speeds, of a conventional port-injection combustion system. Direct-injection technology works well with turbocharging and helps deliver a great balance of power and economy.

Highlights of the Cobalt SS’s Ecotec 2.0L DI turbo engine include:

• Steel crankshaft
• Forged connecting rods
• Oil-spray piston cooling
• 9.2:1 compression ratio
• Aluminum cylinder head with stainless steel intake valves and sodium-filled exhaust valves
• High-pressure engine-driven fuel pump
• Mobil 1 synthetic oil

Components including the steel crankshaft and forged connecting rods are high-strength items that provide strength and enhance durability. Oil-spray piston cooling helps reduce cylinder temperatures and promotes longevity by delivering pressurized oil that continuously lubricates the pistons, which reduces friction. To enhance combustion, the piston tops feature a dish shape that deflects incoming fuel toward the spark plugs.

To accommodate the direct-injection system, the Ecotec 2.0L DI turbo has a unique cylinder head and intake manifold. The cylinder head incorporates mounting locations for the fuel injectors – items that are typically mounted in the intake manifold on port-injection engines. Specialized and extremely precise multi-hole fuel injectors are used to meter fuel and deliver it in a finely atomized manner. They are supported by an engine-mounted high-pressure fuel pump.

Apart from the mounting positions of the fuel injectors, the cylinder head has conventional port and combustion chamber designs. Large stainless steel intake valves and sodium-filled exhaust valves are durable components designed to stand up to the high-performance capability of the engine.

The unique cylinder head, fuel system, pistons and intake manifold are the major components that differentiate the 2.0L DI turbo from other members of the Ecotec engine family. Mobil 1 synthetic engine oil is installed at the factory. Synthetic oil was selected for its friction-reducing capabilities and high-temperature performance.

Turbocharger and charge air cooler

Pumping up the Cobalt SS’s 2.0L Ecotec engine is an intercooled turbocharger system. The turbo blows pressurized air into the combustion chambers to enhance horsepower and torque, while the system’s intercooler circuit cools the turbocharged air charge to maximize its effect. The turbocharger is sized to deliver a significant horsepower boost and almost no spool-up lag. Maximum pressure is almost 20 psi.

Because the pressurized air pushed by a turbocharger becomes heated, the Cobalt SS’s system employs an air-to-air intercooling system. With it, the pressurized air passes through a heat exchanger mounted behind the grille in the lower front fascia, where it is cooled before it enters the engine. Cooler air is denser, enabling the combustion chambers to draw in more air for maximum power. The cooler air also staves off the possibility of detonation at higher temperature, which allowed engineers to tune the engine for maximum power and ensure consistent performance in all driving conditions.

Transmission

Backing the turbocharged engine is a standard GM Powertrain Sweden F35 five-speed manual transmission. Semi-synthetic transmission fluid is used for its capability of absorbing heat and resisting breakdown during high-performance driving.

A performance-oriented feature referred to as “no-lift shift” allows maximum performance – upshifts can be performed very quickly without lifting the throttle. An algorithm in the engine’s controller enables this high-performance feature, which helps maximize acceleration and gear changes.

A short-throw shifter with stiffened shifter bushings and modified cables and attachments enhances confidence behind the wheel, giving the driver a firmer, more direct and quicker shift feel. A limited-slip differential is available with the manual transmission.

3.82:1 final drive ratio

The Cobalt SS’s powertrain has a 3.82:1 final drive ratio, which was selected because it allows the turbocharged engine to remain in the optimal section of the torque band during shifts and while driving competitively on a racetrack. This enhances both the car’s tangible performance measures and intangible fun-to-drive quotient.

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