Automobiles have become an essential part of our economy and provide a convenience that most have become dependent on, however they have also had a dramatic impact on our health and environment. As a result there is an incentive to find ways to more efficiently use conventional fuels and decrease emissions while alternative fuels and vehicles are being developed. This research involved studying the effects of adding small amounts of hydrogen and hydrogen and oxygen to a gasoline fuelled spark ignition (SI) engine. The hydrogen and oxygen were added in a ratio of 2:1, mimicking water electrolysis products. It was found that the effects of hydrogen addition (2.8% of the fuel by mass, 60% by volume) were negligible when operating at fuel/air equivalence ratios ≥ 0.84. When operating at equivalence ratios (&phis;) ≤ 0.78 the torque and indicated mean effective pressure (imep) were increased and cycle-to-cycle variation decreased with hydrogen addition. On the other hand, the NO emissions increased on average by a factor of 3.5 for &phis; ≤ 0.78. The improvements in engine performance and increase in NO emissions were related to a faster burn rate. In tests where less hydrogen was added (1.7% by mass) it was found that the bulk of the improvement observed previously had occurred with the first 1.7% addition. Further, the addition of hydrogen only and hydrogen and oxygen in a ratio of 2:1 were compared. The extra oxygen had little effect on engine performance, however a definite increase in NO emission was seen (500 ppm).; It was calculated that twice as much power was necessary to generate the hydrogen on board through electrolysis than what was gained from the engine.
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