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In carburetted engines the lever is called throttle lever and controls the mass flow rate of the air-fuel mixture delivered to the cylinders by the amount of throttle valve opening. In engines with fuel injection system, the lever is typically referred to as power lever and controls the amount of fuel that is injected into the cylinders.
A throttle body is somewhat analogous to the carburetor in a non-injected engine, although it is important to remember that a throttle body is not the same thing as a throttle, and that carbureted engines have throttles as well. A throttle body simply supplies a convenient place to mount a throttle in the absence of a carburetor venturi.
In this article, the terms multi-point injection (MPI), and single-point injection (SPI) are used. In an MPI system, there is one fuel injector per cylinder, installed very close to the intake valve(s). In an SPI system, there is only a single fuel injector, usually installed right behind the throttle valve.
When the throttle is opened (in a car, the accelerator pedal is depressed), ambient air is free to fill the intake manifold, increasing the pressure (filling the vacuum). A carburetor or fuel injection system adds fuel to the airflow in the correct proportion, providing energy to the engine. When the throttle is opened all the way, the engine's ...
Under part throttle conditions (i.e. when the throttle is less than fully open), the effective compression ratio is less than when the engine is operating at full throttle, due to the simple fact that the incoming fuel-air mixture is being restricted and cannot fill the chamber to full atmospheric pressure. The engine efficiency is less than ...
A cable from the throttle is connected to the oil pump indicating throttle's position. A tube ensures flow of oil from the reservoir to the oil pump. This system is commonly used for motorcycles as it eliminates the need of pre-mixing fuel and two-stroke oil. Vespa is an example where pre-mixing of two-stroke oil is required. Automatic ...
The advent of concern about fuel economy and emissions had major impacts on engine design. Some of the trade-offs reduced throttle response. Most new cars employ a drive-by-wire system, which includes electronic throttle control and can itself either reduce or increase throttle response (Depending on whether or not it's being employed on a performance car).
Most petrol engines were carbureted, sucking the fuel/air mixture into the engine, while the diesel only sucked in air and the fuel was directly injected at high pressure into the cylinder. In the conventional four-stroke petrol engine the spark plug commences to ignite the mixture in the cylinder at up to forty degrees before top dead centre ...