4. Ideal Cycles for Forced-Induction Reciprocating Engines

The equations for the mean effective pressure (mep) show that it can be boosted by increasing the pressure p₁ at the start of the compression process. For a given heat input, boosting the mep results in increased cycle work and torque. This can be done in real engines by employing a small compressor to raise the atmospheric pressure of the air before it is delivered to the engine. If the compressor is driven by the high-temperature and high-pressure exhaust gases (the former can be as high as 1000 K and the latter significantly higher than the ambient pressure) the boosting system is known as turbocharging. If, on the other hand, the compressor is driven mechanically by the engine itself, the system is known as supercharging. In some cases, the two systems can be compounded to provide very high degrees of boosting.