Low-Temperature Starting Experiments with a Mazda Rotary Engine 740161
A study of the low-temperature cranking and starting characteristics of the Mazda engine is described. Measurements were made at around - 10°F, using a Mazda R-100 car in a cold room. For these experiments, the seal lubrication system-in which the oil is mixed with the fuel in the carburetor-was separated from the conventional bearing lubrication system.
Cranking speed was found to vary inversely with the viscosity of the oil in the sump and to be independent of the viscosity of the seal lubricant. Compression pressure was proportional to cranking speed; oil viscosity had no direct effect on compression pressure, but was important only as it affected cranking speed.
A brief investigation was also made of an apparent icing problem which hindered starting of our Mazda engine at low temperatures. The results suggest that water of combustion, produced in the first few cycles of cranking, may freeze and prevent the sealing grid from functioning properly.