Combustion performance of methane, iso-octane, toluene and methanol in a spark-ignition engine

Results are presented here for the burn rates of methanol, methane, toluene and iso-octane, at four combinations of speed and load, in a spark-ignitio n engine with a four-valve pent-roof combustion system. The results have be en obtained for a range of ignition timings with relative air-fuel ratios i n the range of 0.9 to 1.3. The burn rate results have been validated by mea ns of a computer simulation, which has also been used to make predictions o f the nitric oxide emissions, for comparison with experimental data. The re sults showed that methanol burnt the most rapidly, that toluene was not qui te so fast, and that iso-octane was for the most part the slowest. Methane was also shown to have a slow burning rate. The nitric oxide emissions were greatest with toluene, and lowest with methane; results that were consiste nt with the computer predictions. The discussion includes reference to the limited other data that are available.