I know this subject has been covered some already, but I'm interested in peoples thoughts on which engine will provide the most power for a given steam source: A 2 cylinder, double acting, reciprocating engine of the vertical marine type, a 2 cylinder, double acting oscillator, or a V-4 single acting engine like the saito V4PR?
The 2 cylinder, double acting, reciprocating engine used in marine designs comes to mind first. Four power strokes per revolution, on 2 pistons with relatively small contact area, D valves which can be made pretty leak proof. But, on the downside, you have a smaller piston area on the back side because of the piston rod, potential problems with the piston rod seal, piston rod and crosshead friction.
A 2 cylinder, double acting, oscillator doesn't have problems with the crosshead friction, but shares the piston rod friction and seal issues. And it has the added problems of potentially leaks around the cylinder ports. I'm assumming the added friction of the cylinder against the standard would be similar to the added friction of the D-valves in the reciprocating engine.
A 4 cylinder single acting engine like the Saito V4 seems like it has a lot of advantages and not many disadvantages. It's true you have the added friction of 2 more pistons, 2 more connecting rod journals, and 2 more valves, so I don't know how this design would compare to the other two.
Anybody have some insight into this subject?