The Sunbeam land speed cars produced in the period 1912-1929 mainly used Sunbeam's own aero engines to provide the high power output needed.
Initially sidevalve V8 and V12 units were used in Coatalen's 'Toodles' racing cars during the Edwardian period. (220hp V12 Mohawk shown above)
[This engine powered a number of reconnaissance and bomb-carrying planes used in WW1, notably the Short 184 which saw action in the Gallipoli campaign and the battle of Jutland]
After the first world war, more advanced overhead valve aero engines were used (due to the technology developments that had been accelerated by the hostilities) like the 350hp 18 litre V12 used in the 1920 LSR car later bought by Malcolm Campbell and renamed 'Bluebird'. This was a one-off hybrid engine utilising V12 Sunbeam Manitou crank and crankcase with unique cylinder heads based on the 3-valve per cylinder V8 Sunbeam 'Arab' design. (Malcolm Campbell on the left perhaps giving supporting words to his mechanics in this pic)
The one exception for the sunbeam LSR attempts (in not being derrived from an aero-engine design) was the 1925 Tiger which used a 4 litre V12 that was a development of earlier 2 litre 6-cylinder Grand Prix racing car engines, but with twice as many cylinders, and initially a pair of rootes superchargers. It developed around 300bhp.
Aero engines featured again in the 1926 '1000hp' LSR car, this time a pair of 22 litre V12 Sunbeam Metabele units, which was a slightly updated version of the WW1 Cossack design, retaining the same crankcase and cylinder head design, but using aluminium cylinder blocks instead of iron. One engine was mounted ahead of the driver, one behind. The rear engine was started first by compressed air, then the front engine was started through a mechanical friction clutch. Once synchronised, they were locked together with a dog clutch for the record attempt.
(pic below of preserved Sunbeam Cossack V12 aero engine at the Smithsonian museum, built under license by the Stirling Engine Co, Buffalo, N.Y)
In 1930 the new Silver Bullet LSR car once again used a pair of large capacity Sunbeam aero engines, which were a one-off design built solely for the record car (although perhaps with the hope of generating publicity for a new breed of Sunbeam aero engine). These were a more modernised design and featured all-enclosed camshafts and valve gear, aluminium castings throughout, a billet steel crankshaft, oversquare bore/stroke configuration, and a large centrifugal supercharger geared to 17,000rpm. Unfortunately the Sunbeam engineers were working round the clock to complete the project in time and so development and testing period was extremely limited (especially when compared to the very well-tested and developed Napier Lion and Rolls Royce V12 aero engines used in other land and water speed records at that time). Sadly they did not perform as intended and were the last Sunbeam record/race engines to be produced before the company folded.
(Close up of the enormous centrifugal supercharger and Amal carburettors which according to contemporary reports were the source of engine troubles on the Silver Bullet's record attempt at Daytona Beach)
For the reasons above, the current motivator for this project is a 6 litre De-Havilland Gipsy Major aero engine.
The original Gipsy aero engine was designed in 1927 by Frank Halford for the Moth biplane. In 1932 it was redesigned to run in an inverted configuration to allow the propellor to run in a higher position whilst allowing the pilot to see past the engine. From an initial 100bhp output it was improved gradually up to 200bhp in the last variants. It powered the Tiger Moth in the 1930s and later the Chipmunk DHC-1 postwar. It's main advantage is relative simplicity and lightweight construction. A supercharged Gipsy Major was used by the Stanton Brothers in the 1950s to gain the New Zealand national speed record at 154mph, then later 173mph in the same car with a streamliner body.