|The 2010 Ecotec 2.4L I-4 VVT DI (Direct Injection) for Chevrolet Equinox. Click to enlarge.|
GM is introducing two new direct injections engines—a 2.4-liter inline four cylinder unit and a 3.0-liter V-6 unit—with initial application on the 2010 Chevrolet Equinox. The more fuel efficient direct injection engines replace the larger 3.4L and 3.6L V-6 engines on the 2009 models.
The 180 hp (134 kW) 2.4L DI engine, which will replace the current entry-level 3.4-liter V-6, delivers an estimated 30 mpg US highway (EPA certification pending). By comparison, the older 3.4L engine produces 185 horsepower (138 kW), but with a rated 24 mpg US highway.
The Equinox will join a growing roster of direct injected vehicles from GM, including the all-new 2010 Cadillac SRX crossover and 2010 Buick LaCrosse sedan, which, along with the Equinox, debut in January at the North American International Auto Show in Detroit. For the 2010 model year, GM will offer more DI models in North America than any other manufacturer. In 2009, GM expects to sell 500,000 vehicles with gasoline direct injection.
Along with direct injection technology, both the 3.0L DI and 2.4L DI engines use variable valve timing to optimize power and fuel efficiency across the rpm band, as well as reduce emissions.
2.4L DI. The new 2.4L DI VVT engine delivers an estimated 180 hp (134 kW) @ 6700 rpm and 172 lb-ft of torque (232 Nm) @49,00 rpm. It uses technology based on GM’s other four-cylinder direct injection applications, but with unique features designed for its specific application. This includes an 11.4:1 compression ratio that helps build power, slightly dished pistons that increase combustion efficiency and injectors with an application-specific flow rate.
GM benchmarked the best fuel system and noise attenuation products to provide customers with quiet operation.
3.0L DI. The new 3.0L DI engine is a variant of GM’s family of high-feature DOHC V-6 engines that also includes GM’s 3.6L DI engine in the Cadillac CTS—an engine named to Ward’s AutoWorld’s 2009 “Ten Best Engines” list for North America, for the second consecutive year.
The 3.0L is rated at an estimated 255 hp (187 kW) and 214 lb-ft of torque (290 Nm), for a power-to-displacement ratio of 85 hp per liter. (Output will vary by model.) By comparison, the current high-end 3.6L V-6 on the Equinox delivers 264 hp (197 kW) @ 6,500 rpm and 250 lb-ft (339 Nm) of torque @ 2,300 rpm.
The 3.0L DI features an isolated fuel injector system that reduces the direct injection high-pressure fuel system pulses for quieter operation. Rubber isolators are used with the fuel rail to eliminate metal-to-metal contact that would otherwise transmit noise and vibration from the high-pressure fuel system.
Because the fuel is injected directly into the combustion chamber, direct injection uses higher fuel pressure than conventional fuel injected engines. This is enabled by a special high pressure pump driven by one of the engine’s camshafts.
Cold starts. On cold starts, direct injection can be controlled to create a richer air/fuel mixture around the spark plug, making it easier to ignite in a cold engine. This results in a smoother operation of the engine and lower emissions during the cold start and warm-up, when most harmful tailpipe emissions are typically created. GM’s direct injected engines reduce cold-start vehicle emissions by 25%.