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).
Test report on a semi-expanding carburetter, detailing modifications to the throttle bore and their effect on induction pipe depression.
| Identifier | ExFiles\Box 13\4\ 04-page115 | |
| Date | 28th February 1933 | |
| E.{Mr Elliott - Chief Engineer} from Hs{Lord Ernest Hives - Chair}/Swdl.{Len H. Swindell} c. to By.{R.W. Bailey - Chief Engineer} Hs{Lord Ernest Hives - Chair}/Swdl.{Len H. Swindell}2/KT.28.2.33. SEMI EXPANDING CARBURETTER (LEC.3137). Further to our preliminary report on this carburetter, we have tested a throttle bore of 2.375 this being machined out from 2.25 dia. which is at present used. In order to keep a smooth uptake the hot spot was machine tapered to 2.375 dia. Although giving a 20% increase in free area, the induction pipe depression was only reduced from 2.4" Hg to 2.3" Hg. at 3000 r.p.m. By removing the seat, this increasing the air valve port from 2.375 dia. to 2.500 dia., there was no measurable decrease in depression. From the following results it will be seen that only by radical alterations to the existing large carburetter could the induction pipe depression be appreciably lowered. As no practical improvement is obtained we do not recommend any increased uptake or throttle body diameter which would lower the velocity with the probability of upsetting the distribution. The tabulated depressions although comparative are slightly lower (approx .2"Hg) than shown on our previous report, as the engine we at present using is not fitted with the latest (114° E.82448) camshaft, and therefore only giving 160 BHP. as against 175 BHP. at 3000 r.p.m. Hs{Lord Ernest Hives - Chair}/L.Swindall. | ||