Fiat were one of the early aviation-engine companies, and their petrol engines were used later on in the Schneider Cup races in the 1930's, as well as for Italian aircraft builders or more mundane machines. The company took one of it's existing petrol (gasoline) engines, the A12, and converted it to diesel running as the AN1.
Back in the UK, the Bristol Company were experimenting with heavy-oil engines at the request of the Air Ministry, and a
single test engine of 7.375" X 12" was constructed using techniques similar to those already used on the Jupiter engine.
This single cylinder engine is said to have developed 68 hp at 1000 rpm, or 75 hp at 1100 rpm. A 100-hour endurance test
was completed successfully, and ran in the test bed for nine months without being stripped down. A lot of work on
injection systems was conducted on this test engine, with injection gear from Ricardo, Bosch and Bristol being tried.
The chief engineer at Bristol at this time was to become famous in later years through his development of the sleeve-valve
engine for Bristol, his name was A.H.Roy Fedden. Fedden was to dominate the engineering of Bristol Aircraft for many years,
and had the famous Bristol rotaries to his credit, most of which were developed into supremely reliable and economical
aircraft power plants.
An earlier engine, the 'Phoenix', based on the 'Pegasus' radial had nine cylinders and a capacity of 28700 cc, or 1767
cu ins with bore and stroke of 5¾" X 7½". This was fitted into a Westland Wapiti biplane for tests in 1933, and
a later test in 1934 gave the aircraft the world height record of 27.453 ft for a compression-ignition engined plane.
Fuel consumption was 35% better than the Jupiter engine at cruise.
Fiat AN1 Aero Diesel Engine
Fiat AN1 Aero Diesel Engine
Bristol Phoenix Diesel Aero Engine Side View
Bristol Phoenix Diesel Aero Engine Rear View