Correlation of combustion noise with ignition-timing in an IC engine

The need for development of a more efficient IC engine is always on the rise which can be related to oil being a non-renewable resource and its increasing carbon foot print causing global warming. In addition to the CO2, there are more toxic pollutants such as NOx, CO and HC due to improper combustion. These demands have paved way for development of alternative fuel engines such as bio-diesel, bio-ethanol and hybrids. Still these engines need to optimise their combustion to get the best of both worlds. And for the purpose of optimisation there must be a means to measure and estimate the combustion characteristics. Thus analysing the combustion noise gives some insight into the performance of the engine.