An old 3.5 HP Briggs & Stratton lawnmower on which tests were carried out. Although it was made in '74, the engine is still mint and appears more powerful than new ones! Water injection tests turned out as a big failure simply because the water was dumped into it instead of vapourized. Propane is one fuel it guzzled like crazy (and the same applied to gas before it was given a higher compression ratio). Later it was retrofitted with a fuel vaporizing system and sold--the retrofit cut consumption by a third!
