| Designation | Sun |
| Bore | 3/4 inch |
| Stroke | 3/4 inch |
| Configuration | Vertical twin cylinder, single acting |
| Height | 4 inches |
| Length | 4 3/4 inches |
| Weight | 2 lb 9 oz |
| Extra equipment | Drain cocks Displacement lubricator |
| Taps required | 5, 7 BA 1/4 x 32 tpi 5/16 x 26 tpi |
| Notes | Designed for running on either saturated or flash steam, the engine is capable of powering a boat to 54 inches long (or 66 inches using two engines, driving twin propellors). For saturated steam applications the castings could be supplied with a slide valve, making the engine easier to build. For superheated and flash steam, a stainless steel piston valve was specified. |