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This paper presents the methodology and results of vapour pressure measurements and vapour phase composition determinations of M20, M50, M70 and M85 methanol-gasoline blends. These blends were chosen to span the range of composition which could be found in a variable fuel vehicle tank. Vapour pressures were measured at seven temperatures from -40°C to 40°C and at vapour liquid ratios of 4:1 and 500:1. The vapour phase composition was determined for these two vapour liquid ratios at temperatures of -28.9°C (-20°F) and -17.8°C (0°F). This paper also compares the theoretical predictions of vapour pressure and fuel/air equivalence ratio of the Royal Military College multicomponent fuel volatility model to the experimental measurements.

The temperature and pressure of the charge, reached at the end of the compression stroke when an engine is cranked for starting, decide whether it will start and attain selfsustained running. These, in turn, are affected by the crevice volume in, and the blowby from, the engine, particularly at cold ambient temperatures and low cranking speeds. This paper presents a model to estimate these effects. Tentative values are proposed for the parameters that appear in the model based on experiments performed on small engines motored in a cold chamber. The model can be incorporated in engine cycle simulation programs to allow for crevice and blowby effects. It is impossible to prevent gas leakage entirely from an operating reciprocating engine. Gas may leak at the valves, the cylinder head gasket, the spark plug gasket, the injector gasket and the piston rings. The gas that leaks from the cylinder past the piston rings into the crankcase is termed “blowby”.