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).
Engine improvements, piston ring issues, and comparative data from other manufacturers like Bugatti.
| Identifier | ExFiles\Box 131\4\ scan0351 | |
| Date | 9th July 1937 guessed | |
| -2- (5) Sr. and Michelin's car have improved. Reason - (1) A certain amount of carbon has been formed in the scraper and ring pressure ring grooves which damps the ring from flutter. (2) Oil pressure gradually falling due to wear of bearings velocity of oil diminished, consequently, probably less oil on cylinder wall. ---------- The distortion of the cylinders must have an adverse effect at high speed upon piston ring steadiness. ---------- Reasons why new type piston skirt dia. and heavier wall pressure scraper ring give better results. (1) Piston vibration damped down by the fit of the skirt. (2) Pressure rings not as liable to flutter. (3) Scraper ring will not flutter and will follow distortion of cylinder wall to a greater extent. (4) The effect of piston fit not allowing the amount of oil up the cylinder wall, is admitted. ---------- One thing must be remembered, these French drivers go like nothing on earth, its all or nothing. The ones that do not have reasonable oil consumption until wear takes place. ---------- I have obtained the following information from the Chief Engineer of Bugatti's. To his car he has fitted Bonalite pistons fitted with Perfect circle rings - 3 compression rings. 2 scrapers with numerous small holes, similar to what we used to have. At high speeds he has improved his oil consumption from 1 lite per 1000 KLS. to1litre per 5,600 KLS. These are American so you will most probably know all about them. Rm{William Robotham - Chief Engineer}/GWH.{George W. Hancock - Head Chateauroux} | ||