Testing and modelling the effect of high octane petrols on an adapted vehicle

Report no. 8/20: Gasoline combustion has traditionally been measured using Research Octane Number (RON) and Motor Octane Number (MON) which describe antiknock performance under different conditions. All European gasoline cars must be capable of running on the 95 RON petrol grade, however some vehicles are calibrated to be able to take advantage of higher octane fuels available in the market, typically by advancing spark timing or increasing boost pressure which allows more power and perhaps also better fuel consumption.

In the future vehicles may be made available which have increased or variable compression ratio which can fully take advantage of higher octane but these are not commercially available at present. This engine modelling and vehicle testing study was carried out to understand the effect of high octane fuels on the efficiency of a downsized higher compression ratio engine.