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).
The performance comparison and mechanical faults of a 20 HP exhaust cutout.
| Identifier | ExFiles\Box 74\4\ scan0184 | |
| Date | 8th April 1923 | |
| Y4134 Hs.{Lord Ernest Hives - Chair} from TMW. Hs{Lord Ernest Hives - Chair}/TMW1/LG18.4.23. 20 HP. EXHAUST CUTOUT. X4269 ~~Y4134~~ Attached will be found a report of the above fitting showing a comparison of performance having the cutout open and closed. It will be seen from this report that although the power curve shows a slight increase with cutout open, it is not apparently sufficient to give any indication of increased H.P. on the road either for acceleration, hill climbing or high speed work. It also has certain mechanical faults such as :- (1) A bad rattle from the front butterfly valve due, no doubt, to the fact that this must be very sloppy to allow for expansion. (2) The rear butterfly valve has a tendency to stick when it has remained closed during the cooling down process; the contraction evidently trapping the valve in the position taken up when hot. (3) The long connecting rod the two valves is very springy and in the case of (2), prefers to bow instead of pushing open the valve. Hs{Lord Ernest Hives - Chair}/TMW. | ||