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Ward’s 10 Best Highlights Gasoline Direct Injection (GDI) Engines

Different types of gasoline direct injection.

Ward’s has announced its 10 Best Engines awards for 2006 with a focus on improved fuel economy as well as performance.

Ward’s editors noted the importance of two engineering developments on this year’s list: gasoline direct injection (GDI) technology and forced induction. Bill Visnic, Ward’s senior technical editor, called direct injection technology “the most important development the powertrain sector has seen in this decade.”

A gasoline direct injection (GDI) engine sprays the fuel directly into the combustion chamber of each cylinder (as opposed to a port fuel injection (PFI) or carburetor engine) and delivers significantly increased performance and decreased fuel consumption and emissions.

First-generation GDI systems are wall-guided—the spray hits the wall, and the formation of the fuel-air cloud depends mainly on the charge movements. A spray-guided technique uses the injection procedure itself and not the charge movement to ensure that a combustible mixture is brought to the sparkplug at exactly the right time, regardless of pressure and temperature conditions.

Three of the 10 Best feature gasoline direct injection:

  • The Audi 2-liter TFSI (Turbocharged Fuel Straight Injection), combined with a variable-geometry turbocharger delivers 200 hp (147 kW). The injector, located on the admission side in the cylinder head, is served by a high-pressure pump driven by the camshaft and a pressure reservoir shared by all cylinders—the common rail system.

    The injector regulates fuel delivery with millisecond intervals, at injection pressures of up to 110 bar. By comparison, a manifold injection system operates at between four and six bar.

    With the 2.0-liter TFSI, the Audi A3 accelerates from 0–100 km/h in 7.0 seconds with combined fuel consumption of 8.8 liters/100km (26.7 mpg US) and CO2 emissions of 211 g/km.

  • The Mazda 2.3-liter DISI (Direct Injection Spark Ignition) combines with turbocharging to generate 256 hp (191 kW) with combined fuel consumption of about 12.7 l/100km (22.3 mpg). (Earlier post.)

  • The normally aspirated Toyota 3.5-liter engine uses two injectors per cylinder to combine direct injection with a conventional port fuel-injection system. The high-pressure fuel system uses a pump driven by a dedicated lobe on the exhaust cam. A proprietary direct injection injector generates a fan-shaped spray pattern.

    The port injectors are secondary injectors. Unlike traditional staged injection where the secondary injectors come online as boost is introduced or high load is realized, this engine runs only the direct injectors at high loads. The engine—the 2GR-FSE—delivers 306 hp (228 kW) and combined cycle fuel consumption of about 11.9 l/100 km (23.7 mpg).

Other engine makers are moving rapidly to implement more sophisticated GDI schemes.

BMW, for example, has stated that it will implement spray-guided direct injection on all its gasoline models in the future, as well as regenerative braking and stop/start functionality. (Earlier post.)

DaimlerChrysler has shown a concept hybrid applying a spray-guided GDI V6 in a hybrid powertrain for a S-Class car. (Earlier post.)

Ward’s 10 Best Engines 2006
AutomakerEngineTest Vehicle
Audi 2L FSI turbocharged DOHC I-4 Audi A3
Audi 4.2L DOHC V-8 Audi S4
BMW 3L DOHC I-6 330i
DaimlerChrysler 5.7L Hemi Magnum OHV V-8 Dodge Charger R/T
Ford 4.6L SOHC V-8 Mustang GT
GM 2L supercharged DOHC I-4 Chevy Cobalt SS/td>
GM 2.8L turbocharged DOHC V-6 Saab 9-3 Aero
Mazda 2.3L DISI turbocharged DOHC I-4 Mazdaspeed 6
Nissan 3.5L DOHC V-6 Infiniti G35 6MT
Toyota 3.5L DOHC V-6 Lexus IS 350/td>



the improvements made by these DI engines is good, but the fuel economy figures are still very poor since the engines focus moe on performance. Applying all this technology to a small 3cyl 1L engine would provide ample powerand even geater fuel economy gains. It seems progress is yet to make more fuel economic cars, as carmakers compete for performance.


Running cost or vehicle handling, you have to choose one. Whoever make one car that have the best of both will win the price.


America wants individualism. We want to be different from our neighbors. We have to have that special car that no-one else has.

When we get past that, it will not matter what the performance. People will get in their boxes and let the box drive you to work.

Better yet, take the bus! Nah, that just means people would have to get up earlier and actually walk.

Rob C

Seems like the best possible use of DI technology would be on a two stroke engine. DI would make the engine clean (injection could happen after exhaust ports close) and the power to weight ratio could be much better than for a 4 stroke with all its valve drive gear and its need to turn twice to get a power stroke.

Where are the 2-stroke gas DI engines?


Regarding the 2-stroke gas DI engines, look at Their engines are currently used in small displacement scooters... Fuel economy seems to be about 2x better than the carburated equivalents.

Chris Stewart

Direct injection at current air/fuel ratios is a different dress on the same ol' gal.

Here's something for the thinkers & seekers...
Compression ignition with a gasoline direct injection, by whatever means, similiar to diesel does away with air/fuel ratios and the fuel will burn in an oxygen rich atmosphere for a more complete "process" to quote the term from the late great Smokey Yunick.


Gasoline engine's are really very popular now day's.


Features and out put of this GDI engine are good..

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