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).
Modifications to Bentley cylinder heads to increase power output and the results of related tests.
| Identifier | ExFiles\Box 86\1\ scan0141 | |
| Date | 9th March 1935 | |
| 7219 To Sg.{Arthur F. Sidgreaves - MD} & Wor.{Arthur Wormald - General Works Manager} c. to E.{Mr Elliott - Chief Engineer} c. to By.{R.W. Bailey - Chief Engineer} c. to Hs{Lord Ernest Hives - Chair}/Md. c. to Bn.{W.O. Bentley / Mr Barrington} Hs{Lord Ernest Hives - Chair}/Mths.{Reg Matthews}3/KW.9.3.35. Bentley Cylinder Heads. Further to the report "Comparison of Cylinder Heads, circulated 20.2.35. we have now increased the output of the Lec.3862 Cylinder Head so that it now gives a greater power output than EB.2050. This has been done by machining away slightly the turbulent lip round the inlet valves to the following modification Ex.16041 and increasing the diameter of the exhaust valves to 1.300. As far as could be ascertained the modification to the turbulent lip has not affected the head for detonation, but these tests have been carried out since the unit completed 20 hours endurance on E.B.2050 cylinder head, and during that time the unit lost approximately 4 H.P. at the low speeds. From our tests the curve for maximum ignition advance avoiding detonation after the modification is almost identical with the curve before the modification, but the low speed M.E.P. is approximately the same in both cases. It will be noticed on the power curves that since fitting the 1.300 dia. exhaust valves the power does not fall off so rapidly above 4,000 r.p.m. Since machining the turbulent lip the low speed M.E.P. has increased an appreciable amount. Attached are curves E.V. 78 & 79. Hs{Lord Ernest Hives - Chair}/R.Matthews. | ||