Lotus Mark IV was a trials car by Colin Chapman built on an Austin 7 chassis. Chapman’s success at building trials cars brought another previous customer, Mike Lawson, to order a second trials car in 1952 to replace his Lotus Mark II, in which he won the Wrotham Cup. Once again Chapman chose an Austin Seven as the starting point, reinforcing the frame and installing a four-cylinder 1172cc (71.5ci) Ford sidevalve engine. Chapman used all the tricks he had learned in his previous cars, constructing a lightweight aluminum body with a rounded nosecone. He fitted a 3-speed transmission taken from a Ford 8 and the divided front axle as on his previous cars.
Lawson won his class in the very first attempt in this car, following up with others, solidifying Chapman’s reputation as a designer and engineer. The success of this car, and other requests for more cars, led Chapman and Michael Allen to establish Lotus Engineering in a disused stable in Hornsey.
Ford Sidevalve Motor
Configuration: S4 SV
Displacement: 1172 cc
Bore/Stroke: 63.5mm x 92.456mm (2.5x3.64")