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).
Progress report on carburetion and performance tests on experimental cars.
| Identifier | ExFiles\Box 123\1\ scan0054 | |
| Date | 22th May 1940 | |
| f 1036 To Ev.{Ivan Evernden - coachwork} from Rm{William Robotham - Chief Engineer}/TAS.{T. Allan Swinden} c. to JNP. CARBURATION PROGRESS. Following is a catalogue of carburation items, ideas and progress on experimental cars:- 3.B.50. Engine unit B.60 No.4 The main carburetter drive at the moment is taking place on this car. Six induction pipes are available and of these the three S.U. pipes have been tested. Standard bore is 1.6". 1 3/4" bore causes 1 1/2 m.p.h. loss in top speed. 1 1/4" bore causes 2 1/2 m.p.h. drop. No resulting economy is apparent, in fact the reverse is the case at middle speeds. Maybe this is due to upsetting of the economy ramming action. The largest Stromberg pipe, first of its kind to go onto a car, is now being fitted. As sidelines we have investigated the effects on economy of heafy engine oil, and worn and new road tyres. The change from Castrolite to Motorine C causes a drop of about 1/2 m.p.g. throughout the constant speed range 20 to 70 m.p.h., i.e., the percentage loss increases with engine speed. The change from smooth 4 ply Dunlop rear tyres to 3/4 new tyres has no effect up to 50 m.p.h. At 60 m.p.h. consumption drops 1/2 m.p.g. and at 70 m.p.h. it drops 1 m.p.g. Attention was drawn to this effect by a 3 second increase in 10-70 acceleration time with the newer rear tyres. 8.B.V. This car now has fitted the S.U. automatic choke which started life on 2.B.50. 2.B.50. has a completely standard B.V system. The anti-freeze starter off 8.B.V. is on loan to Hunt at Clan. This choke has had a lot of teething troubles, but it now seems to be settling down. One objectionable feature is that you have to depress the accelerator to bring in the fast idle for a cold start. -cont'd- | ||