Characteristics of Fuel Economy and Output in Methanol Fueled Turbocharged S.I. Engine

Abstract

One outstanding feature of methanol as an alternative fuel for spark ignition engines is its very high antiknock characteristics. In this study, potential improvements in output power and thermal efficiency that methanol offers for a supercharged compression ratio S.I. engine as an automotive prime mover were investigated. They were compared with those of a naturally aspirated gasoline engine. As a result the effect of operating parameters such as supercharged boost pressure, charge temperature and exhaust back pressure on thermal efficiency and output power was clarified quantitatively. Next it was confirmed that a methanol fueled turbocharged 1.3 liter S.I. engine with high compression ratio of 11:1 achieved almost the same output performance as that of a gasoline fueled naturally aspirated 2.0 liter engine. This engine also realized a lean burn system with high compression ratio and low NOx characteristics of methanol and achieved extremely good roll economy. The improvement in thermal efficiency was as much as 30 percent compared with a naturally aspirated gasoline engine having the same engine size.