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To improve the cold starting and low load driveability problem in a methanol fueled car, a reformed methanol fueled S. I. engine with a small methanol reformer using exhaust thermal energy as a heat source was developed and tested. A half of methanol supplied to engine was reformed to hydrogen and carbon monoxide, and the rest was supplied in a liquid state. As a result, this engine produces less power than the neat methanol fueled engine. But brake specific fuel consumption of this engine is lower based on the calorific value than that of neat methanol fueled engine in the wide range of excess air ratio. The CO emission levels are not significantly different, whereas the HC emission levels are lower than those from the neat methanol fueled engine. The NOx emission levels are higher than those from the neat but this problem can be solved by lean burn.

To improve the cold startability of methanol, methanol-butane mixed fuel was experimented. Engine performance and exhaust emissions are obtained with methanol-butane mixed fuel. These characteristics are compared with those of methanol and gasoline. The mixing ratios of methanol and butane are 50:50 (M50), 80:20 (M80), and 90:10 (M90) based on the calorific value. As a result, M90 produces more power than gasoline and more or less than methanol depending on the engine speed and the excess air ratio. Brake horse power of M90 is higher than that of gasoline by 5 - 10 %, and brake specific fuel consumption is smaller than that of gasoline by 17 % to the maximum based on the calorific value. NOx emission concentrations for M90 are lower than those for gasoline and higher than those for methanol because of the effect of butane, CO emission concentrations are somewhat lower than those for methanol and gasoline.