From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Fitting new pistons and rings to Commander Briggs' car, drawing comparisons to aero engine designs.
| Identifier | ExFiles\Box 181\M8\ img025 | |
| Date | 4th July 1917 | |
| To E.P.) from R.{Sir Henry Royce} EH. C to Commander Briggs. C to J.{Mr Johnson W.M.} X 2369. R4/B4.7.17. X.682 RE WING-COMMANDER BRIGG'S CAR. X.2369 On a recent occasion during a visit to Commander Briggs re aero engines, I rode in the Rolls Royce car which he uses. During my visit, he expressed a wish to have tested some pistons with narrow rings which the Admiralty have been using in Aero Engines. These appear to be the same as those of our recent practice, except they are still narrower, being only .06" wide instead of .1". I do not think that for a car engine of the usual type that narrow rings then .1" could be considered practical. I suggest therefore, that we fitt to Commander BRIGGS car a set of pistons similar to those fitted to 7 CA, which consist of four upper rings .1" wide pinned alternately front and back, and a lower scraper ring with some surface below the ring, to retain the oil and reduce the risk of piston knocks. 7CA was particularly good in this respect although fitted with aluminium pistons. Referring to the type of piston, I think it is highly desirable to retain the Zephyr type for the reason that the distortion is less, and therefore the freedom of the piston is probably greater, and secondly the top of the piston keeps cooler owing to the heat being carried off more effectively. This is advantageous, as you know because it enables the engine to fill up better and therefore give more power, and is also advantageous especially when using aluminium for a piston, to keep it as cool as possible. 2937 Commander Briggs also desires that we fit one of our | ||