How fuel injection works
Unlike older engines with carburetors, today's engines are fueled by fuel injection. The control is done electronically. In this case, a defined quantity of fuel is injected at a certain position of the pistons (flow rate).
Advantages of gasoline injection compared to a carburettor
- Reduction of fuel consumption (due to better metering and supply of petrol).
- Higher power density (thanks to optimal cylinder filling).
- Less harmful exhaust gases.
- Engine conditions are better taken into account (warm-up, overrun).
Why is the injection quantity calculated?
When designing a car, the injection quantity is calculated in order to be able to design the injection pump and its control parameters. The injection is controlled via the engine control unit in order to be able to optimally supply your engine with fuel at all times. The software of the ECU (engine control) can even take into account the properties of different fuels. So you almost always get the same performance - regardless of the fuel.
What does the injection quantity mean for supercharged engines?
Charged engines with turbochargers or superchargers require more fuel than naturally aspirated engines. This is due to the fact that there is a higher internal pressure (boost pressure) and also higher temperatures. The high oxygen content in the combustion chamber can also be used to burn more fuel. Naturally aspirated engines can therefore also run lean mixtures, while turbocharged and supercharged engines require richer mixtures. With the right injection quantity, the efficiency of the engine increases and you achieve more performance. And that's exactly what we want to achieve with tuning.
What is the duty cycle?
The duty cycle (duty cycle) indicates the working cycle of an injector: The relative time that an injector is on and fueling during an engine cycle (intake, compression, combustion and exhaust). For example, a duty cycle of 80% indicates that the injector is held open 80% of the time and closed 20% of the time. If the engine requires more fuel, the duty cycle increases so that more fuel gets into the engine. A duty cycle of 100% is referred to as a static duty cycle. The injection valve can no longer control the fuel supply, which can indicate that the valve is too small.