The D-Motor LF26 is a lightweight liquid cooled side-valve four-stroke flat four, 2.7 litre petrol aircraft engine, produced by D-Motor in Deerlijk, Belgium.
This direct-drive aero-engine is unusual in two respects: it is very oversquare with a bore:stroke ratio of 1.295:1, and it has a side-valve (flathead) valvetrain. The designer determined that since maximum continuous power output (65.3 kW) was to be developed at only 2800 rpm, the extra weight and complexity of overhead valves (OHV) would be superfluous. The resulting engine is compact and lightweight, with a dry weight of , and a maximum power-to-weight ratio of 1.09 kW/kg (wet; coolant fluids weigh ). The engine has port injection, a dry sump lubrication system, and dual ignition.
With the aid of funding from the Belgian government, D-Motor has developed a derivative 4-litre flat-six engine, the D-Motor LF39, which is claimed to produce and to have dry weight of .
Reference: D-Motor