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).
Camshaft comparison between the Eagle V111 and Eagle 1X.
| Identifier | ExFiles\Box 43\1\ Scan088 | |
| Date | 26th August 1925 | |
| R.R. 493A (50m) (D.B. 175 25-9-24) J.H.D. EXPERIMENTAL REPORT. -2- Expl. No. REF: Hs{Lord Ernest Hives - Chair}/TAG/LG26.8.25. is fitted with Eagle 1X. camshafts, which have 24° overlap that there is a big increase in power over the Eagle V111. type camshaft which has no overlap. The Eagle V111. curve is very flat, and drops heavily from 2050 r.p.m, whereas the other curve continues to rise, and is still rising at 2300 r.p.m. but has a tendency to flatten. The increase at 2300 r.p.m. = 78 B.HP. over the Eagle V111. camshaft. Note :- On each of these curves a small timing diagram is given shewing the inlet opening and closing (the exhaust timing is standard) position for the respective camshafts they represent, also a small sketch intended to convey an idea of the induction system layouts. The B.HP. figures are corrected for barometer and temperature on all the curves. CURVE 11. CAMSHAFT COMPARISON. The engine was fitted with :- (1) Eagle V111. camshafts (no overlap) (2) Eagle 1X. " (24° " ) (3) Eagle 1X. carburetters and induction system. (4) Standard pistons 5.25 to 1. The fitting of the Eagle 1X. type carburetters and induction system has the effect, when used in conjunction with the Eagle V111. camshafts, of giving a straight curve with increased H.P. up to 2130 r.p.m. after which there is a sudden droop as in Curve 1. With the Eagle 1X.(overlap) camshaft, the curve continues to rise at 2300 r.p.m. without any signs of flattening out. The increase at 2300 r.p.m. = 51 B.HP. contd:- | ||