Double Overhead Cam engine, supposedly faster than a Bently at the time.
The Sunbeam's engine was of 2,920 cc six cylinder
It featured inclined valves operated via easily adjustable tappet levers by two overhead camshafts,
an important innovation at the time. The cylinder head and block were formed from a single casting
which was then considered normal for high-performance engines. One of the novel features of the
engine was its use of dry-sump lubrication whereby engine oil was drawn from a
tank positioned beside the engine.

The cylinder bores translated into a fiscal horse-power rating of 20.9 hp