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).
The full load power curve tests of the 'SS' engine, comparing it to the Phantom engine.
| Identifier | WestWitteringFiles\S\June1928-August1928\ Scan139 | |
| Date | 28th August 1928 | |
| To R.{Sir Henry Royce} from Hs{Lord Ernest Hives - Chair}/ACL. c.c. to BJ. Wor.{Arthur Wormald - General Works Manager} c.c. to E.{Mr Elliott - Chief Engineer} DA.{Bernard Day - Chassis Design} c.c. to BY.{R.W. Bailey - Chief Engineer} ORIGINAL Hs{Lord Ernest Hives - Chair}/ACL1/LG28.8.28. RR. 'SS{S. Smith}' ENGINE. X7771 (crossed out) X7770 We have had the 'SS{S. Smith}' engine running for several hours under light loads and have now obtained a full load power curve. For these tests we used an Eagle Claudel Carburetter with a free choke area of 1.532 sq.ins. and open exhaust i.e., short open pipes to each port. The peak of the power curve was reached at 2750 r.p.m. giving an output of 129.6 B.HP. The power fell to 119.5 B.HP. at 3000 r.p.m. The compression ratio was measured and came to 4.5. The power curve was not continued below 1000 r.p.m. because below this speed the carburation became erratic. The max. BMEP. recorded was 110.2 lbs/sq.in. On an appended print will be seen the power curve of this engine together with curves for the std. Phantom and a Phantom of 4.6 to 1 comp: ratio using the same carb. as used for the above tests. We see the power output of the 'SS{S. Smith}' engine is better than the high compression Phantom, which difference we believe due to the larger inlet valves. The valve timing employed was as shewn on one of the prints but we shall test timings on either side of this to see if we have selected the best. The power peaks at about 2750 r.p.m., higher than on the Phantom but we should contd:- | ||