Mitsubishi GDI Engine (Part One)

GDI engines are engines direct injection gasoline. The first production model to equip one was the Mitsubishi Galant in 1996 (main image), although over time more and more engines with this type of injection have appeared due to its numerous virtues. The first one: a low consumption of fuel and a very good power. The Mitsubishi GDI engine has been one of the first to emphasize pollution reduction as a fundamental premise.

It is an engine that uses the basic scheme of a multipoint injection system, which combines several elements that allow you to slightly vary the fuel injection, which applies directly inside the cylinder. The main characteristics of these motors are:

vertical intake manifold

The first of these is the vertical intake manifold, which controls airflow for high performance, as well as increasing the amount of air supplied for mixing.

The shape and internal surface of the collector greatly affects combustion which can be obtained later in the cylinder. This GDI engine intake architecture combines with the piston deflectors once air enters the combustion chamber.

piston deflectors

The piston deflectors consist of a spherical cavity at the top, contributing to the air taking a cylindrical flow when entering the chamber and concentrating the fuel on the spark plug.

They are not to be confused with deflector pistons which are used primarily in two-stroke engines with crankcase compression. Those are designed to direct the flow of air in such a way that it can then be evacuated well. While in GDI four-stroke engines its function is to promote proper detonation.

High pressure GDI direct injection

The engines Mitsubishi GDI were the first to reach the market in series with direct fuel injection. A configuration that until then was only used in diesel engines. Its objective was to reduce fuel consumption and polluting emissions through a more exact supply of fuel, directly into the combustion chamber.

This, combined with the fact that the gasoline injectors of the GDI engines work at very high pressure, allows optimize combustion over a very wide rev range.

As an addition, the fuel pump inject fuel into a 50 bar pressure, and it has a pressure sensor to have an effective control of the supply.

Precisely in the injection is where it is the main disadvantage of these motors. As the injectors are in contact with the heat generated in the cylinders get dirty and clog easily due to the appearance of carbon. That is why it is advisable to use an injector cleaner for gasoline engines from time to time. However, this has been remedied to a large degree in the engines gasoline with direct injection current.