The Valveless was an English automobile manufactured, after lengthy development, from 1908 until 1915 in Huddersfield, Yorkshire. The successor to the Ralph Lucas Valveless, the car marked the entry of the David Brown & Sons group into the manufacture of motors. Its engine was a 20 or 25 hp duplex two-stroke model which was advertised as having "only six working parts"; these included two pistons, two connecting rods, and two crankshafts, which were geared together and counter-rotated. This is a type of engine configuration known as a split single since it is effectively a single cylinder split into two.
20 hp 2-cylinder 133 ÃÂ 140 = 3.891 litres
25 hp 2-cylinder 133 ÃÂ 140 = 3.891 litres
15 hp 2-cylinder 112 ÃÂ 127 = 2.503 litres
15 hp 2-cylinder 118 ÃÂ 127 = 2.503 litres
19.9 hp 2-cylinder 127 ÃÂ 127 = 3.217 litres
19.9 hp 2-cylinder 127 ÃÂ 133 = 3.546 litres