Direct Injection - Technology Delivers More Green & More Power

Rex Roy

Truly useful technologies always seem to find their way into the market. This helps explain the proliferation of toilets, shoe laces, paper clips, and today, direct injection.

While electronically-controlled sequentially-fired intake-port-positioned fuel injection has been the standard fuel delivery system for more than a decade, this technology is steadily being supplanted by direct injection. Examples are varied and legion.

Direct Injection EFI Explained
Direct fuel injection places a fuel injector nozzle inside the combustion chamber as opposed to the current norm: just upstream of the cylinder head's intake valve(s). The in-the-chamber positioning allows for more precise metering and delivery of fuel, thereby improving the efficiency of every combustion cycle. Because the fuel is more efficiently consumed, power goes up and nasty emissions go down.

Where Direct Injection EFI Is Used
At the 2008 Los Angeles Auto Show, Porsche announced that the improved 3.6-liter flat-six engine used in the revised 2009 Boxter S and Cayman S models will now feature direct injection. This announcement begs the question; what took Porsche so long? Regardless of the answer, the new cars now have more power and offer marginally better fuel economy.

The 2.0-liter DI four-cylinder engine in the Pontiac Solstice and Saturn Sky beat the Porsches to market when these GMs debuted as 2006 models. Members of the media and Congress might be surprised to know that DI is currently available in the proletariat Chevrolet Malibu when the optional 3.6-liter V-6 is specified. General Motors began offering this DI engine in the 2008 Cadillac STS that debuted late in the summer of 2007.

Each of the aforementioned vehicles consumes gasoline, but DI likewise delivers benefits in diesel engines. The corporate 3.0-liter V-6 and 2.0 diesels from Volkswagen/Audi use the technology, as do the diesels available to power Ford Super Duty and Dodge Ram HD pickups.

DI On The Snow
Direct injection has also just been introduced on snow machines. For the 2009 model year, Ski-Doo now offers a 600-cc two-stroke two-cylinder engine that utilizes direct injection. The improvements over traditional EFI two-stoke performance is staggering.

Ski-Doo's Rotax-branded 600 H.O. E-TEC engine produces approximately 120 horsepower (that's about 200 horsepower per liter). The new engine burns straight gasoline because it uses oil-injection (fed by a separate oil supply) for lubrication. This setup eliminates the traditional blue oil smoke trail emitted by most two-stroke snowmobiles. The DI Rotax is currently the cleanest-running engine in the snowmobile industry, and has earned the EPA's Clean Air Technology Excellence Award.

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