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).
Comparison of the connecting rod and piston assembly weights between a Pierce Arrow and a Phantom model.
| Identifier | ExFiles\Box 23\4\ Scan013 | |
| Date | 1st January 1928 | |
| To OY. from Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} X4588 Hs{Lord Ernest Hives - Chair}/Rn{Mr Robinson}2/LG2.1.28. X8030 X.4588 COMPARISON OF PIERCE ARROW AND PHANTOM CONN. ROD PISTON ASSEMBLY. It is interesting to note the weights of the Pierce Arrow connecting rod and piston given in Automotive Industries Nov. 5th./27. The Pierce Arrow stroke and pin dia. are idenitcal with that of the Phantom, the bore is 4" against the Phantom 4.250. The weights of the conn. rod and piston assemblies are as follows :- Rolls-Royce - 5.87 lbs. Pierce Arrow - 3.062 lbs. Assuming the Pierce Arrow bore to be increased to 4.250" and the weight of the piston to go up as the square of the dia., the weight of the total assembly only becomes about 3.362 lbs. so that proportionately the Pierce Arrow is 70% lighter on these parts than we are. Could you ascertain for us if the figures given in 'The Automotive Industries' are correct, and if so, we should be vitally interested to obtain a set of Pierce Arrow parts if this is at all possible. Crank Pin. P.A. 2.125} 20H.P. 1.5} Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} 20H.P. 3 X 4 1/2 Assembly 2.621 20.H.P- Real Pierce Arrow 3 1/2 X 5. Assuming wht go up as bore square Pierce arrow should weigh 2.621 x 17.21 / 16 = 3.5 | ||