The Carburetor Single-point or throttle body injection (TBI) Port or multi-point fuel injection (MPFI) Sequential fuel injection (SFI) Direct injection
More About The Types Single-point or throttle body injection (TBI) The earliest and simplest type of fuel injection, single-point simply replaces the carburetor with one or two fuel-injector nozzles in the throttle body, which is the throat of the engine’s air intake manifold.
Port or multi-point fuel injection (MPFI) Multi-point fuel injection devotes a separate injector nozzle to each cylinder, right outside its intake port, which is why the system is sometimes called port injection. Shooting the fuel vapor this close to the intake port almost ensures that it will be drawn completely into the cylinder.
Sequential fuel injection (SFI) Sequential fuel injection, also called sequential port fuel injection (SPFI) or timed injection, is a type of multi-port injection.
About GDI Gasoline direct injection (GDI) - to significantly improve fuel efficiency without making a major shift away from conventional internal combustion technology. Mitsubishi, Toyota and Nissan all market four-stroke GDI engines in Japan.
Major Objectives of the GDI engine
• • •
Ultra-low fuel consumption that betters that of even diesel engines Superior power to conventional MPI engines A Stable Combustion
Why Not Carburetor ?? Carburetor has following Disadvantages : Vapour lock, Perfect air/fuel mixture cannot be obtained, Lack of throttle response, Low volumetric efficiency, Icing – problem in aircraft engines, Compromises on emission,
Why The GDI ?? • • • • • •
Lower Fuel Consumption and More Output Better than the current MPI Style of Fuel Injection Ultra-precise computer management The location of the injector Less pollution from each drop of gasoline. The World needs a better Environment
Recent Developments A new 2.0 L DOHC 4-valve direct-injection (DI) gasoline engine has been developed which features new technologies such as
swirl intake ports pistons with a concave combustion chamber high-pressure fuel-injection
It has been confirmed that a vehicle with this system successfully improves fuel economy while satisfying emission requirements.
Technical Features • Upright straight intake ports
for optimal airflow control in the cylinder
• Curved-top pistons for
better combustion
• High pressure fuel pump to
feed pressurized fuel into the injectors
• High-pressure swirl injectors
for optimum air-fuel mixture
Disadvantage Complexity and Cost : Direct injection systems are more expensive to build because their components must be more rugged -- they handle fuel at significantly higher pressures than indirect injection systems and the injectors themselves must be able to withstand the heat and pressure of combustion inside the cylinder.
Conclusion Gasoline direct injection (GDI) engine technology has received considerable attention over the last few years as a way to significantly improve fuel efficiency without making a major shift away from conventional internal combustion technology. In many respects, GDI technology represents a further step in the natural evolution of gasoline engine fueling systems.
