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).
Comparison report on standard hot spot and preheated intake air engine systems.
| Identifier | ExFiles\Box 50\3\ Scan277 | |
| Date | 26th June 1926 guessed | |
| contd :- -2- First it was necessary to establish a basis of comparison for the two systems under consideration i.e., the standard hot spot and the preheated intake air. Consequently the criterion was taken as the extent that these systems would maintain a high percentage of power over a wide range of mixture strength when the preheating was such that, as near as possible, the maximum power obtainable from each system was the same. The first test was made with exhaust heat to the bend and after the mixture and ignition has been adjusted to give the maximum torque, the ingoing air temperature was varied by means of an electrical heater and the torque for the various air temperatures recorded. A speed of 750 r.p.m. full throttle was selected for the tests in order that any difference in distribution between the two systems - which naturally would be worse at low speeds than high - would be as marked as possible. The curve connecting intake air temperature and M.E.P. is given here and shews that the power increases with increase of air temperature, due to correction of distribution. We were unable to get above 80°C air temperature but from the curves it seems that this is its point of maximum M.E.P. No doubt after this the M.E.P. would fail due to decrease in volumetric efficiency becoming more rapid than any improvement in distrib- ution. contd :- | ||