Specials & Sports Cars

Using Ford Sidevalve Components

Lotus Badge


Lotus Engineering Co. Ltd.,
7, Tottenham Lane
London N.8.

(1951 – 1959)


As so much has been published about Lotus cars, this page is limited to the Lotuses that were fitted with Ford sidevalve engines. The Lotus name was first used by Colin Chapman in 1947 when he registered his first Austin 7 special trials car, fitted with a tuned Austin 7 sidevalve engine. This became known as the Lotus Mk I. It is thought that the Lotus name came from Chapmans interest in Buddhism and the letters on the badge come from his initials, Anthony Colin Bruce Chapman.
The Lotus Mk1 followed in 1949 with the Mk II 1172cc Ford sidevalve powered trials car built on a “boxed” Austin chassis. Chapman sold the Mk II to Mike Lawson (Stirling Moss’s uncle).

Lotus MkII

Lotus Mk II

The Lotus Mk III was an Austin 7 special designed as a road/race car for the new 750 Formula and was notable for Chapman’s ingenious reading of the rules. With Chapman’s driving the Lotus Mk III caused the rule makers to redefine the 750 formula rules.

The Lotus Mk IV was a trials car built for Mike Lawson, the suspension was more sophisticated than the MKII and was very successful.

Lotus Mk IV

Lotus Mk IV

In 1951 Chapman launched the company Lotus Engineering Co.

1952 a Lotus Mk VI prototype was completed, this was the car which set the firm on the way to success. In 1953 the Lotus MK VI was launched as a kit car for assembly by the amateur enthusiast, using the E93A 1172 cc Ford engine. The bare chassis strong multi-tubular weighed a mere 55lbs and with all brackets. panels etc; only 90Ibs. The E93A gave way to the 100E Ford sidevalve engine in the later Lotus VI models but all self assembly components continued to be off the shelf Ford suspension, brake, gearbox, axles, wheels, etc., with a Lotus modified swing front axle to provide independent front suspension. By 1955, some 110 Mk VI cars had been sold, of which the majority were equipped with tuned Ford sidevalve engines.

Lotus 6

Lotus Mk VI

The aerodynamic Lotus Eleven began production in 1956 and the Series 1 of 1956/7 featured swing front axles whilst the Series 2 of 1957/9 was fitted with independent wishbone front suspension similar to the Lotus 7. Lotus offers three forms of this classic Sports Racing car:

LE MANS - with Coventry Climax 1098 cc OHC engine disc brakes and de Dion axle.
CLUB - with Coventry Climax 1098 cc OHC part tuned engine drum brakes and live rear axle.
SPORTS - with 1172 cc Ford 100E tuned sidevalve engine, drum brakes, live rear axle, framed windscreen and weather equipment for road use.

Only seventeen Series 1 and ten Series 2 Lotus Elevens were fitted with Ford sidevalve engines.
In February 1957 Motor Sport a test report was published on the Lotus Eleven Sports.
Some details from the test report:
Price £872 (£1308, inclusive of purchase tax)
The power output was in the region of 40bhp and its safe engine speed of 5250rpm. Speeds in gears at maximum safe rpm; First 35mph, Second 69mph, Top 89mph.

Given a really long run under favourable conditions about 95 mph is attainable, and if the screen is discarded and the red mark on the rev-counter ignored this remarkable Ford engine, which runs up to 6000rpm will propel the Lotus at comfortably above 100mph.

Lotus Eleven

Lotus Eleven

Lotus Eleven with Willment Overhead Inlet Valve Cylinder Head

Lotus Eleven

Lotus Eleven


Lotus Seven S1
The successor to the Mk VI was the Seven S1, introduced at the 1957 Motor Show. Some early models continued with the 1172 cc sidevalve engine but these were superseded by the 105E 998 cc and later 1098 cc OHV engines from the later Ford Anglia.


A Ford 100E sidevalve powered car shown as a kit 'straight out of the box'.  It must have been rare, indeed, as it seems all was there ready to assemble! Lotus claimed that the car could be built in 12 hours; however one of the first kits took the owner a full four months to complete, due to the inability of Lotus to supply all of the parts in one kit at one time.
This Model still produced after 57 years in updated versions, this must be one of the most successful car designs of all times.