Although the Minor was originally designed to accept a flat-4 engine, late in the development stage it was replaced by a 918 cc side-valve inline-four engine, little changed from that fitted in the early 1930s Morris Minor and Morris 8, with a bore of 57 mm but with the stroke of 90 mm and not 83 mm, and producing 27.5 hp (21 kW) and 39 lbf·ft (50.3 N·m) of torque.