DETROIT — The upcoming and highly anticipated Pontiac Solstice GXP will feature General Motors' first North American application of a gasoline direct-injection or GDI system, a report says.
The setup will improve fuel economy, boost torque and lower cold-start emissions. The GDI system on the Solstice GXP comes on a turbocharged Ecotec 2.0-liter, four-cylinder engine, according to AutoTech Daily. It will produce 260 horsepower and 260 pound-feet of torque, with the highest specific output for any GM engine ever: 2.1 horsepower per cubic inch of displacement. Buyers will have the choice of a standard five-speed manual gearbox or an optional five-speed automatic.
GM engineers in the United States and Europe jointly developed the engine. GDI injects fuel directly into the combustion chamber instead of into an intake port. Audi has pioneered GDI technology in Europe and North America and has said it plans to convert nearly all of its gas engines to a direct-injection configuration in the next 10 years.
MITSUBISHI'S NEW GDI SYSTEM. Mitsubishi now has a production direct injection gasoline engine that reportedly delivers 35 to 40 percent better fuel efficiency than an indirect multiport injected engine. The engine also puts out 10 percent more torque and meets all emission requirements, including the ones for oxides of nitrogen (NOX) which are especially tough to meet.
The Gasoline Direct Injection (GDI) engine, which is expected to be a forerunner of the next generation of high-efficiency, low- emission engines, is currently being produced in Japan and will be introduced in Europe later this year. The engine is slated to make its debut in the U.S market by the year 2000.
The GDI engine runs on an ultra lean (40:1) air/fuel ratio at idle by using special injectors that produce a "stratified" charge in the combustion chambers. Regular gasoline fuel injectors produce a fine cone-shaped mist that's necessary to create a homogeneous air/fuel mixture. The high pressure GDI injectors, by comparison, produce a very compact spray pattern that forms a swirling cloud of fuel particles. This, combined, with a "reverse tumble" air flow in the cylinders creates a layered effect (stratified charge) of air and fuel in the cylinder that is rich in the immediate vicinity of the spark plug but is progressively leaner further out.
One of the keys to making this work is the way air is directed into the cylinders. Most engines have horizontal intake and exhaust ports so air and fuel enter past the intake valve, blow past the spark plug and swirl back around the cylinder in a circular path before being ignited. In the GDI engine, the intake port is almost vertical. Air flows down from the top, enters past the intake valve and injector, flows down the side of the cylinder until it hits a cup shaped pocket in the piston dome that redirects it back up towards the spark plug. This "reverse flow" arrangement combined with relatively late injection timing in the compression stroke allows the engine to handle very lean mixtures at idle without misfiring. When more power is needed, injector timing is advanced earlier in the compression stroke and more fuel is injected into the cylinder to create a more conventional fuel mixture.
Lean burn engines that produce exceptionally low carbon monoxide and hydrocarbon emissions have usually had problems meeting NOX emission standards because elevated combustion temperatures increase the formation of NOX. But the GDI engine overcomes this problem by using more exhaust gas recirculation (up to 30 percent EGR flow rate) to dilute the incoming air, and a special blend of catalysts in the catalytic converter. The result is a 97 percent reduction in NOX emissions compared to a conventional engine says Mitsubishi.
The GDI engine is a dual overhead cam design that displaces 1.8 liters and has a compression ratio of 12 to 1. The injectors operate at pressures approximately 15 times higher than ordinary indirect gasoline injectors.
It's obviously going to be awhile before this technology starts turning up on cars here, but it is a preview of what's to come as the auto makers scramble to meet the next tier of low emission standards coming out of Washington D.C.
Like the all the fuel injection systems that have come before it, the new direct injection engines will still require replacement parts and will likely suffer from similar injector woes that plague today's engines. In fact, direct injection injectors may prove to be even more troublesome than today's indirect injectors because they're exposed directly to the heat of combustion. Time will tell.
good stuff this could help out our economy greatly! i was worried that american companies wouldnt be able to keep up...
i hope this pushes all the other manufacturors to follow this route. direct injection is really a wonderful thing. i know honda will make it reliable
this is great for us tuners as well, not only can we adjust the cam timing and lobes, but now the fuel injector timeing, not just duration. and the egr valve.... yea we can just tell that thing to shut up.
gdi 
this could help out our economy greatly! i was worried that american companies wouldnt be able to keep up...
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