The Kemp K4 diesel was the first model engine which is definitely known to have been designed by Harold Kemp, one of the unsung heroes of British model diesel development during the pioneering era. This bulky and very heavy sideport diesel had a displacement of 4.4 cc (0.268 cuin.).
The K4 first appeared on the Britsh market in early 1947 as the initial product of the Kemp Engines company of Gravesend in Kent. The tiny 31/2 man workshop operated by Harold Kemp had a very limited production capacity which was soon challenged by the introduction of further models to accompany the K4 in the range. As a result, the K4 was produced in very limited quatities. Despite its bulk and weight (11.11 ounces!), the engine acquired a good reputation as a dependable, easy-starting and fine running unit. The company could sell all that it could produce - the problem was that there weren't that many to sell!
Kemp Engines also produced a very few examples of an 8.8 cc twin-cylinder diesel based upon two K4 piston/cylinder assemblies. This was familiarly known as the Black Devil. It was an extremely expensive engine to produce, dictating a high selling price which dissuaded most potential customers. As a result, this is a mega-rare engine today. Even the standard single-cylinder K4 is far from common.
The K4 survived in limited production until mid 1948, when the Kemp Engines business was sold to the K Model Engineering Co. Ltd., also of Gravesend. At that point it was withdrawn and later replaced by the front rotary valve K Vulture of 5 cc displacement.
Full details and a bench test of the Kemp K4 diesel will appear shortly in a new article on this website.