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).
Series of tests on exhaust system configurations, materials, and their performance.
| Identifier | ExFiles\Box 14\6\ Scan252 | |
| Date | 1st November 1931 | |
| -3- as follows - Suggested ORIGINAL E80256 Downtake pipe thickness .184" ) /160 .104 E82574 Intermediate pipe " .104" ) Weight .064 Cast Iron expansion box ) 41 lbs 12 ozs. thickness .250 ) /160 .080 Weight of standard system complete 29 lbs 4 ozs. 1.11.31. Cast iron expansion box machined down to .187" Result - As good as .250" Weight of exhaust system now 40 lbs 8 ozs. 3.11.31. New exhaust system fitted with downtake pipe entering front end of expansion box as per sketch - [Sketch of pipe system with labels: .104", 1"1/2"D, .104", .064"] Downtake pipe thickness .104" Intermediate pipe " .064" Expansion box " .104" Tested with no lagging Result - 25% better than standard system with no lagging. Exhaust booms are apparent on this system and standard system at 32 m.p.h. and 50 m.p.h., but are considerably lessened with cast iron box and reinforced pipes. 5.11.31. Straight through pipe .064" thick fitted from exhaust manifold to main rear silencer. Result - Poor, very tinny, bad exhaust boom 30 - 35 m.p.h. forward. 13.11.31. | ||