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 diagnosing a 'boom' noise by modifying the exhaust and concluding that vibration is the likely cause.
| Identifier | ExFiles\Box 137\4\ scan0116 | |
| Date | 10th November 1930 | |
| -3- We now thought that having improved the boom a lot by engine mountings, the remainder might be exhaust. Three restriction baffles were fitted between the cylinder head and exhaust manifold. These reduced the area to half its standard size. No change was found in the boom. The car was then towed at 2250 R.P.M. in second gear without push rods. The boom was still evident. This confirms what we previously found out, that Vibration rather than exhaust is responsible for our present boom; the front expansion box and modified manifold having already dealt with the exhaust side of the problem. Our next step is to see if the crankshaft with balance weights has any effect on the noise. Hs{Lord Ernest Hives - Chair}/I. A.{Mr Adams} Leslie. | ||