Performance tests, conclusions, and recommendations for the 'Silver Ghost' chassis.
| Identifier | ExFiles\Box 47\1\ Scan162 | |
| Date | 20th October 1925 guessed | |
| -3- Temp. of water in radiator at top of hill. 88°C. Temperature artificially raised at bottom of hill to 96.5C. Signs of water just at boiling point. Temperature at top of hill 94°C. No signs of water boiling after first two hundred yards of climb. Tests were made with four people up. Car fully closed, & full equipment. Considerable reduction of vibration experienced previously at 50 km. per hour. The results of tests after repairs show an improvement over tests made pre repairs. Unfortunately, atmospheric temperatures play an important role in these tests, and no definite opinion can be formed until the car has been run under Mid-Summer condition, and it may be anticipated from our tests that an improvement will be experienced. It should be noted that pre-repair capacities were taken with carboned pistons, whereas the after repair capacities were taken with clean pistons and cylinders. The engine, as it is at present, will have a tendency to increase its compression, as it carbons up, and should keep cooler in consequence of slightly increased power. (I do not think we may fear increased vibration). The conclusions arrived at from these experiments confirm the opinion that "Silver Ghost(1907 40/50 historic RAC 15,000 miles trial)" chassis should have a compression ratio of not less than 4.25 to 1, or 61 lbs. per sq. inch. (Liquid capacity test is more reliable than a test by pressure gauge). Secondly, care should always be taken to undercut the rubber insertion washers for water pipes. Thirdly, slipper drives should be assembled with a maximum resistance of 15 lbs. applied at the end of a 17" lever. This is believed to be standard setting at Works, and the writer believes that slipper drives increase their resistances, up to a certain point, even with Bakerlite washers, after being in circulation for several months. This latter is an interesting point. Fourthly, Butterfly valves in exhaust down pipes should be on the sloppy side. We recommend that similar tests be made in the Summer months at Paris on our test hill, or better still on the Monte-Carlo Mont-Agel climb, with plain shuttered bonnets, high speed fans, and low speed fans, and fans of different designs. Ps. | ||
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).