| Designation | Star |
| Bore | 5/8 inch |
| Stroke | 5/8 inch |
| Configuration | Vertical twin cylinder, single acting |
| Height | 3 3/4 inches |
| Length | 4 3/4 inches |
| Weight | 18 oz |
| Notes | A high speed, lightweight engine supplied by Stuart as a finished engine only, for racing boats in the 1 metre hull class. Crankcase in aluminium with brass cylinder head and stainless steel piston valve. A displacement lubricator was fitted as standard. |