• Type 
  • Lot number 
  • Location


Engine no. 145

• One of only 60-70 BS1 Mk3 engines made
• Originally installed in a Kieft
• Rare competition type magnesium oil sump
• Incredibly rare 'test report' 1953 on file
• Requires overhauling prior to use

The 1,971cc six-cylinder engine of the BMW 328 featured an ingenious new cylinder head, designed by Rudolf Schleicher, incorporating hemispherical combustion chambers and inclined valves without recourse to overhead, or twin camshafts. Externally, Bristol's Type 85A clone of the BMW motor differed little from the German original, the most obvious difference being the adoption of SU, rather than Solex, carburettors part way through production. The most significant changes made by the Bristol designers were metallurgical, their utilisation of the highest quality materials contributing to increased engine life. A maximum output of 80bhp at 4,200rpm was claimed.

Manufactured in period and intended for competition use, the Bristol BS1 Mk3 engine was the most powerful version available at the time of its introduction, producing circa 140bhp (see list of variants on file). BS1 Mk3 engines were produced in limited quantities; indeed, it is believed that only 60 to 70 were ever made. This particular type of engine was intended for installation in competition cars such as the Frazier Nash, Cooper Bristol, Lister Bristol and Kieft Bristol. Records indicate that this particular engine (number '145') was installed in a Kieft. The BS1 Mk3 was based on the Cooper-specific BS1 but with a Girling viscous crankshaft damper, streamlined carburettor butterflies, redesigned small-nose crankshaft, twin rocker box breather pipes, no oil filter, and a sports type magnesium oil sump.

The cylinder block and head have the correct casting number, and the engine still retains all of its original and extremely rare period-correct components that are specific to Mk3 engines:

2" racing crankshaft
Sports type magnesium oil sump
Correct 3-into-1 cast exhaust manifold
Matched set of carburettors

IN Racing, recognised specialists, confirm the engine is complete including the matching set of original carburettors, but would need to be overhauled before use. It comes with its original test report dated 8th July 1953, which is an extremely rare document to have.

Bonhams 1793
101 New Bond Street
United Kingdom
Contact Person Kontaktperson
First name 
Bonhams Collectors’ Car department