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Mitsubishi Motors Adds World First V6 3.5-liter GDI Engine to Ultra-efficiency GDI Series

April 16,1997

Mitsubishi Motors announces that it has recently developed a new V6 3.5-liter GDI (Gasoline Direct Injection) engine. The new 6G74 V6 3.5-liter GDI power unit joins the company's highly acclaimed GDI engine series which brings together diesel-topping fuel consumption and higher power outputs than a comparable port-injection engine. The original 4-cylinder 1.8-liter GDI engine, the first of its kind(*1) anywhere, currently powers the fast-selling GALANT / LEGNUM series launched in August 1996 and was a major factor in the series selection as Japan Car of the Year. The new engine is a V6 DOHC unit and sees a further evolution in the outstanding characteristics of the GDI concept.

The new V6 3.5-liter GDI engine realizes a 30 percent improvement in fuel consumption, a 10 percent increase in power output(*2) and a 30 percent reduction in emissions of CO2, regarded a factor in global warming. The new engine will power a new RV model due to be launched in the near future.

Mitsubishi Motors currently plans to introduce GDI engines in two sedan and three RV series before the end of the year. To keep pace, the company will boost its GDI engine monthly production capacity from the current 7,000 units to 10,000 units after the Golden Week holiday at the beginning of May, and to 20,000 units in the autumn.

*1: The first V6 engine to realize stratified air supply and ultra-lean burn combustion by injecting gasoline fuel directly into the cylinders.

*2 Compared with Mitsubishi's port-injection engine in the 600rpm---2,500rpm normal operation zone.

6G74 V6 3.5-liter GDI engine



1. Development aims
(1) Diesel-topping ultra-low fuel consumption and reduction in CO2 emissions.
(2) Higher power outputs than the equivalent port-injection gasoline engine.

2. Principal components
Mitsubishi's GDI engines incorporate the following major components:

  • Upright Straight Intake Port, which controls airflow into the cylinder;
  • Curved-crown Pistons, which control combustion behavior;
  • High-pressure Fuel Pump, which injects fuel directly into the cylinders at the high pressures required to achieve optimum lean burn characteristics;
  • High-pressure Swirl Injectors, which effectively and efficiently atomize and disperse the injection spray.
The new V6 3.5-liter GDI engine also incorporates:
  • An electronically-controlled throttle valve, which, in a simple mechanism, controls with very high precision the large volumes of air required to realize lean burn and improve feeling.

These new features realize higher performance across the rev band and also enable a more compact layout in which the major GDI components fit neatly between the two banks of cylinders.

6G74 GDI Specification
6G74 GDI Current 6G74 MPI
Bore x stroke(mm) 93.0 x 85.8 93.0 x 85.8
Capacity(cc) 3,496 3,496
No. Cylinder V6 V6
Vaive train Type DOHC DOHC
No. Valve Inlet x2 / Exhaust x2 Inlet x2 / Exhaust x2
Compression ratio 10.4 10.0
Combustion chamber Curved-crown Flat top
Intake port Upright Standard
Fuel injection Direct into cylinders Port
Fuel feed pressure(kg/cm2) 50 3.3
Gasoline Unleaded premium* Unleaded premium

(*)Specification is for unleaded premium grade gasoline but will run on either unleaded premium or unleaded regular gasoline.


3. Advantages
(1) Combustion mode
The GDI engine employs optimal fuel management, splitting operation into Economy and power zones to achieve ultra-low fuel consumption under normal operating conditions and greater power outputs at higher engine loads.

The Economy zone, where the engine runs on ultra-lean mixtures of between 30:1 and 40:1, covers a wide operating range of speeds up to 100km/h. High-efficiency intake, meanwhile, enables the Power zone to respond to higher output demands at wider throttle openings.

(2) Fuel consumption
In the Japanese 10-15 mode urban cycle, the 6G74 engine returns better mileage than a similar diesel-powered model and achieves an improvement of approximately 30 percent over the current 6G74 MPI (Multi-point injection) engine.

(3) Global environment
The new 6G74 GDI is a more environment-friendly engine, realizing a 30 percent reduction (in the 10-15 mode fuel economy test) in CO2 emissions which are considered a factor in global warming.

(4) Dynamic performance
At normal operating speeds (600rpm---2,500rpm), the new 6G74 GDI power unit achieves a significant increase in low-end torque and delivers 10 percent more power than its port-injection cousin.

In Power zone operation, the new engine delivers smoother and more powerful acceleration than its port-injection cousin thanks to a significant increase in power output and to the improved response unique to direct injection.

Engine Performance

Vehicle Acceleration

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