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).
Comparing the Cadillac 16-cylinder engine to Rolls-Royce's proposed 12-cylinder designs and discussing development.
| Identifier | WestWitteringFiles\U\2January1930-September1930\ Scan194 | |
| Date | 2nd July 1930 | |
| sc. FROM R.{Sir Henry Royce} C. to HS.{Lord Ernest Hives - Chair} PH. CADILLAC. R1/M2.7.30. Referring to your SG{Arthur F. Sidgreaves - MD}15/E1730., if we had made a 16 cyl. car of ordinary HP. everyone would have thought us thoroughly impractical - (i.e. mad.) We think there is no need for 16 cyls. but whatever novelty is made there will sure to be a certain sale for it because of the attention it attracts. The Cadillac has 18% more piston displacement per mile, and would be running at our maximum road speed, about 4000 revs., when we were running 3000 revs., so that with equal weights its acceleration ought to be more, but probably it is not so good in MEP. and mechanical efficiency. The petrol and oil consumption of this type of engine is generally enormous: ours is getting quite high enough. The adjustment of the valve clearance is good. We put on the eccentric, RG.{Mr Rowledge} added a tangent screw. Cadillac has replaced the latter by a well known irreversible automatic adjustment which was long ago (6 yrs) suggested by someone whom I have forgotten (not in our firm.) Double valve springs naturally have different periods, and we use these on all aero engines. Derby have had several for cars but have reported no advantage. Then we gave them taper springs with the hope that the surging period was longer and less severe. We have long ago wished to try 12 cyl. designs ("Buzzard" 1920) but we thought ourselves lucky to get P. 2. last year. To make anything more perfect than P. 2. we recommended 12 cyls. This has been delayed by inverting for aero work, and steam cooling, but some main parts are in the hands of Derby. In the meantime we are held from making more rapid progress by many people asking for many modifications of very minor order to existing work. We shall push on with the 12 cyl. design at greater speed. R.{Sir Henry Royce} | ||