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).
Road performance test report on a Packard 8-cylinder engine, focusing on crankshaft vibration periods.
| Identifier | WestWitteringFiles\Q\December1926-January1927\ 5 | |
| Date | 1st December 1926 | |
| To R.{Sir Henry Royce} from Hs{Lord Ernest Hives - Chair}/An. c. to BJ. Wor.{Arthur Wormald - General Works Manager} c. to RO.{C. C. Rose - Export Manager} E.{Mr Elliott - Chief Engineer} c. to DA.{Bernard Day - Chassis Design} HY.{Tom Haldenby - Plant Engineer} c. to OY. FN c. to EP.{G. Eric Platford - Chief Quality Engineer} ORIGINAL. Hs{Lord Ernest Hives - Chair}/Re3/LG3.12.26. PACKARD - 8-CYLINDER. 4355 Conditions for test :- 4-seater closed coach - 4 passengers. Car weight empty - 2 tons. 4 cwts. Wheel base 11 ft. 4 ins. Track 4 ft. 9¼" Gear ratios 4.6, 8, 15:6. 33 X 6.75" tyres. Suspension semi-elliptic fore and aft. Rebound snubbers fitted only. Displacement/ton mile - Packard 8400 Phantom 6100 (closed). ROAD PERFORMANCE. The main object of the test was to compare the eight-in-line engine with the six. The general impression of the engine was as follows :- CRANKSHAFT PERIODS. This engine had no clearly defined period. However from about 32 to 48 m.p.h. a very pronounced roughness was observed under any considerable throttle opening and which was transmitted to those in the rear seats. The effect was quite objectionable as the speeds in question were always being used on British roads. It would appear that, due to the long crankshaft and low gear ratio, the main crankshaft period occurs somewhere about 40 m.p.h. and that the makers have smoothed this out with a vibration damper to a certain extent. The most agreeable features about the engine were the entire absence of vibration on the overrun, the reduction in torque reaction at contd :- | ||