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).
Ignition curve tests for a Bentley unit with standard and deturbulated cylinder heads.
| Identifier | ExFiles\Box 82\4\ scan0327 | |
| Date | 9th June 1936 | |
| Hs{Lord Ernest Hives - Chair}/Swdl.{Len H. Swindell}22/KW.9.6.36. Bentley Ignition Curves. In a similar manner to the 25/30 we have carried out ignition curves on the Bentley unit, both with the standard turbulent head and the deturbulated head to Lec.5002. These curves are shown on SP.{Mr Spinney}28/9, and our proposed curves are being obtained as near as possible by the makers of the Delco Remy distributors. We have asked for the governor to be started at 250 Engine r.p.m. which if possible will be a considerable help in the improved steadiness of idling as it will enable the static setting of the ignition to be set appreciably later. Defining the two cylinder heads, the standard head (SP.{Mr Spinney}28) has a proposed curve ranging from 4° BTDC at 250 r.p.m. to 28° BTDC at the high speeds. The proposed curve in each case is that which cuts out detonations at low speeds and gives maximum power at high. To cut out the detonations at 500 r.p.m. full throttle with the standard head, the power loss is 1%. The deturbulated head (SP.{Mr Spinney}29) has a proposed curve ranging from TDC at 250 r.p.m. to 32° BTDC at high speeds. The power loss to cut out detonations in this case is approximately 2% at 500 r.p.m. full throttle, in each case on Shell No.1 with a clean cylinder head. A comparative power curve between the two heads is shown on SP.{Mr Spinney}30, and running open exhaust the deturbulated head gives an appreciable increase up to 10 B.H.P. at 4500 R.P.M., 4 lbs/sq.in. M.E.P. at the middle speeds, whilst at the low speeds the power is the same. This comparison is to be checked open exhaust on the 25/30 engine. HS{Lord Ernest Hives - Chair}/L.H.Windall. | ||