Effects of Gasoline Volatility on Warm-up of Automobiles

The effect of mid-range volatility of motor gasoline on warm-up performance of modern Japanese cars was investigated in an all weather chassis dynamometer room, using six late model cars and twelve fuels of different volatility. The warm-up performance of cars and fuels was evaluated in terms of the time required to completely warm-up (warm-up time), the carknock disappearing time and the numerical driveability demerit rating. The warm-up performance was considerably different with different cars tested. Car with a rotary engine performed best. The warm-up performance correlated well with the 30% and 50% evaporated temperatures of a fuel. Also, the warm-up time was best correlated with 50% evaporated temperature, and the carknock disappearing time and driveability demerit were related best to 30% evaporated temperature.