Direct Injection is a variant of fuel injection, whereby an alternative fuel is highly pressurized, and injected via a common rail/fuel line directly into the combustion chamber of each cylinder.
The major advantages of a direct injection engine are increased fuel efficiency and high power output. Emissions levels can also be more accurately controlled with a direct injection system. The gains are achieved by the precise control over the amount of fuel and injection timings that are varied according to engine load.
Additionally, engines operate on full air intake. There is no air throttle plate eliminating air throttling losses in some direct injection engines, when compared to a conventional fuel-injected or carbureted engine, which greatly improves efficiency, and reduces piston ‘pumping losses’. Engine speed is controlled by the engine control unit (ECU) or engine management system (EMS), which regulates fuel injection function and ignition timing, instead of having a throttle plate that restricts the incoming air supply.