| MODEL | VELOCETTE MODEL O PROTOTYPE 1939 |
| Year | 1939 |
| Engine Type | Twin cylinder, four-stroke, two counter-rotating crankshafts, unsupercharged |
| Displacement / Capacity | 586 cc |
| Bore X Stroke | — |
| Compression Ratio | — |
| Cooling System | — |
| Max Power | — |
| Max Torque | — |
| Ignition | — |
| Induction | — |
| Start System | — |
| TRANSMISSION SPECS | |
| Lubrication | — |
| Gear Box | — |
| Clutch | Multi-plate |
| Final Drive | Shaft |
| CHASSIS SPECS | |
| Frame | — |
| Front Suspension | — |
| Rear Suspension | — |
| Front Brakes | — |
| Rear Brakes | — |
| DIMENSION SPECS | |
| Overall Length | — |
| Overall Width | — |
| Overall Height | — |
| Seat Height | — |
| Wheelbase | — |
| Ground Clearance | — |
| Dry Weight | — |
| Wet Weight | — |
| WHEEL SPECS | |
| Front Tyre | — |
| Rear Tyre | — |
| FUEL SYSTEM | |
| Fuel Capacity | — |
| Fuel Consumption | — |
| Top Speed | — |
The Model O was Phil Irving's road-going development of the supercharged Roarer racer: a twin with a separate counter-rotating crankshaft for each cylinder, but unsupercharged. Shaft final drive and a multi-plate clutch were planned, and the bore was enlarged so parts could be shared with the KSS and KTT. Only a single prototype was built and it survives in a private collection.
