The sleeve-valve engines with silence and great low-speed torque were unable to spin fast enough to make full use of new combustion technology and remain reliable.
[6] In the Daimler Twenty-Five the straight-eight was mounted using their Daimler-patented bi-axial design by which flexible support is given to the engine at five points.
The generator on the offside shares a triple belt drive with the water pump and the radiator cooling fan.
[5] The crankshaft was fully counterbalanced, mounted in nine main bearings, and fitted with a vibration damper.
[3] In September 1935 it was announced that the cylinder bore was now increased to 80 mm increasing the engine's capacity from 3.746 to 4.624 litres following the 25% reduction in horsepower tax which took effect on 1 January 1935. intended to provide improved performance but more important lighter running for the engines and a consequent extension of silent and comfortable service.
[11] During 1935 a 3½-litre Straight-Eight open car achieved a maximum timed speed at Brooklands of slightly in excess of 90 mph.