In the relatively peaceful time between world wars, the various hillclimbs and race circuits dotting the British countryside became battlegrounds. To navigate the winding corners on the way to the top, your car had to be nimble, but to ensure you marched up the hill faster than anyone else, there was no replacement for displacement.
Pre-war Riley cars were valued for their innovative engines as well as their low-slung bodies. Riley’s sport-oriented “Brooklands” or “Speed” variants can invariably be spotted still today at the hands of skilled racing drivers, like this talented chap at Goodwood revival in 2019. Though the Riley Nine (and all of the cars and specials it spawned) was seen even in-period as a lightweight, a progressive take on car construction in the Interwar period. The 1.1L inline-four cylinder engine that powered the Nine was a twin-cam wonder, with hemispherical combustion chambers and valves offset by 45 degrees. The only problem is that “Nine” also signified its output – a measly 9 horsepower.
1928 Riley Nine Special
Even at the time, this was not sufficient for the brave British hillclimb enthusiasts. Enter, the ultimate period-correct upgrade: Aeroengine power, courtesy of a 6124cc, air-cooled four-cylinder from a de Havilland Gipsy II. For those unfamiliar with aircraft from the 1920s, it’s worthwhile to witness the power from these pre-war plane engines. This video shows a similar motor, started on a stand at an aviation museum, and it is incredible to watch the operator nearly blown away by the force of the propeller. Instead of nine horsepower, the de Havilland engine installed in this 1928 Riley turns out approximately 175 horsepower with an astounding 380 ft/lb of torque.
The engine swap pushes the already-rapid Riley into new leagues of performance. Reportedly, the Riley Special is now closer to an in-period grand prix car than a “standard” Brooklands or Speed model. Not long after its modifications were completed around the turn of the millennium, the then-owner reported this Riley captured first place awards in the “Vintage” category of “every unlimited sports car class at every sprint and hillclimb it entered,” including Wiscombe, Shelsley Walsh, Loton Park, Prescott, Curborough, and Brooklands.
Dr. Geraint Owen, the mad genius behind this inspired upgrade, gave a driving demonstration of his newly finished Riley de Havilland to an automotive journalist from MotorSport in April 1999. In the piece, titled “Aeroplay,” the journalist describes the effortless acceleration from the aircraft motor:
“… all you need do is keep your right foot well in and progress is swifter than you might ever imagine. In full race trim, with headlights and fairings removed, the Riley is geared to pull comfortably in excess of 100 mph… Have a nice flight.”
With all of that low-end engine power, the Riley de Havilland is comfortable delivering the grunt necessary to champion hillclimbs, as well as vintage racing of all kinds. The healthy output from the engine is transmitted to the rear wheels via a Rolls-Royce 20/25 four-speed gearbox with a straight-H pattern: An appropriately stout gearbox for an airplane engine.
Perfectly suited for vintage racing and rallying, this Riley is practically a fighter plane for the ground. The most recent listing in RM Sotheby’s Private Sale division, this Riley Special is ready for its next brave caretaker.