Fuel conversion efficiency of a port injection engine fueled with gasoline–isobutanol blends

This paper describes the comparative advantages of using isobutanol as a fuel for SI (spark ignition) engines instead of ethanol. An experimental study of fuel conversion efficiency was performed on a port injection engine fueled with mixtures containing 10, 30 and 50% isobutanol blended with gasoline. Efficiency as well as performance levels were maintained within acceptable limits for all three types of fuel blends compared to running the engine on straight gasoline. These results show that isobutanol is an attractive drop-in fuel for SI engines, and can be blended with gasoline in much higher concentrations compared to ethanol, without any modifications to the fuel system or other engine components.

► Fueling a spark ignition engine with gasoline–isobutanol blends.
► Port injection engine fuel conversion efficiency measurement using a chassis dynamometer.
► Performance variation below ±5% with up to 50% volumetric concentration of isobutanol mixed with gasoline.
► A maximum of ∼12% drop in fuel conversion efficiency compared to gasoline operation.
► Very good results obtained without any modifications to the fuel system or other engine components.