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In this study, the combustion of butanol, neat and mixed with gasoline, was investigated on a 0.6 liter two-cylinder spark ignition engine with fully adjustable fuel injection and spark timing, coupled with an eddy current dynamometer. Two isomers of butanol, n-butanol and iso-butanol, were examined. This basic parameter study gives information about potential requirements of engine control systems for butanol FFV. Compared to the traditionally used ethanol, butanol does not exhibit hygroscopic behaviour, is chemically less aggressive and has higher energy density. On other hand, different laminar burning velocity and higher boiling temperature of butanol, compared to gasoline, requires some countermeasures to keep the engine operation reliable and efficient.

To reduce exhaust emissions and dependency on petroleum-based fuels, various alcohols have been considered as gasoline substitutes for spark ignition engines. In the existing vehicle fleet, the use of ethanol, the most widely used alcohol, is practically limited to blends in relatively small concentrations with gasoline, due to its hygroscopicity, aggressivity, substantially lower heat content, and high latent heat. Butanol has relatively low toxicity, can be produced from biomass, and has higher energy density, lower latent heat, lower hygroscopicity and lower aggressivity than ethanol. In this study, the effects of blends of 30% and 50% of n-butanol (1-butanol) with gasoline on combustion process, engine control unit adaptation and exhaust emissions before and after a three-way catalyst were examined on a 1.2-liter, three-cylinder, four-valves-per-cylinder, naturally aspirated port-fuel-injected Skoda 1.2 HTP spark ignition engine coupled to an engine dynamometer.

Bioethanol, produced from renewable sources, is promoted as a fuel in higher concentrations in newer flexible fuel engines, and in lower concentrations in the general fleet. Introduction of a blend of 85% ethanol with gasoline (E85) at a competitive price in the Czech Republic has, however, spontaneously resulted in this fuel being used in “ordinary” engines not adapted for this fuel. This study investigates the operation of a typical gasoline car with fuel injection and three-way catalyst on gasoline, E85, and additionally on a blend of 85% n-butanol with gasoline, as butanol features better material compatibility than ethanol. The car was equipped with a portable, on-board emissions monitoring system and driven along a route comprising city and rural roads, including hills. Multiple runs were made on each fuel to verify test-to-test repeatability.

An ordinary, unmodified port fuel injection spark ignition automobile engine with closed-loop air-fuel ratio control and a three-way catalyst was operated on two butanol isomers, n-butanol and iso-butanol, and their blends with gasoline at steady-state operating points covering both common and potentially problematic regimes. The engine control unit was able to maintain the air-fuel ratio while running on both butanol isomers and their blends with gasoline. Only small changes in the heat release rates, small and insignificant decrease in exhaust gas temperatures, and no excessive increase in emissions were observed. Under commanded enrichment operation, the maximum torque, air-fuel ratio and exhaust emissions were comparable among nearly all fuels tested. The exhaust gas temperatures were comparable among fuels, with a moderate increase observed in some regimes during operation with high share of n-butanol in fuel.