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).
Findings on the exhaust heated throttle and choke valve.
| Identifier | ExFiles\Box 24\5\ Scan027 | |
| Date | 1st May 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}2/LG1.5.25 In order to assist you in your decisions, we should like to put forward the following facts :- (a) The exhaust heated throttle is not a part of the 4-wheel brake change-over. Cars were delivered with this fitted before four-wheel brakes were fitted. (b) From an average of a large number of dynamometer tests on production chassis, the exhaust heated throttle when fitted did not affect the power in the least. (c) The average throttle temperature of the exhaust heated throttle under full power conditions is 65°C at low speeds -100°C to 110°C at high speeds. This shows that actually when the water boils the water heated throttle might be hotter than the exhaust heated. Under average touring conditions the temperature of the exhaust heated throttle varies from 85°C to 100°C. The maximum heat we have measured after driving some time on the hand control - choke valve shut - is 150°C. (d) When we fit the 6-cyl. exhaust manifold to four-wheel brake cars, the reduction in power averages 2% at 2000 r.p.m. This average is taken from a large number of production chassis. (e) The choke valve is not the cause of any of this loss in power, it is possible to close the choke valve 15° at 2000 r.p.m. without reduction in power. (f) On a car fitted with the 6-cyl. exhaust manifold and the choke valve connected up in the standard manner, if we take tests on the dynamometer at various throttle openings and contd :- | ||