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).
Explaining correct carburation through exhaust gas analysis, featuring a combustion chart and a table of gas equivalents.
| Identifier | ExFiles\Box 122\4\ scan0199 | |
| Date | 25th September 1935 | |
| Correct Carburation by Exhaust Gas Analysis Exhaust Gas Analysis is the scientific method of accurately gauging the degree of richness of the mixture supplied by the carburettor under actual running conditions. It enables the finest adjustment of the Carburettor to be made and the results demonstrated visually by the movement of the needle over the scale of the Analyzer. The exhaust gas, passing through the Analyzer, affects the conductivity of sensitive elements in the instrument, and the results are shown on the galvanometer scale, according to the proportion of the gases which compose the exhaust vapours. For complete combustion, Air and Petrol need to be mixed in the proportion of fifteen to one by weight. In practice, this mixture is too weak to give reasonable power and it is established that a ratio of about 13 to 1 is best for most engines, although at speed, the ratio may be 14 to 1. As will be seen from the graph opposite, an Air Fuel ratio of 13 to 1 gives a Fuel loss of 4%, and a Power loss of 11%. If the Carburettor should be set at too rich a mixture, say of 11 to 1, then the Fuel loss will be 10%, and the Power loss 8%. It will be seen that, in this case, for an increase of only 3% of Power, the Fuel consumption has been increased by no less than 6%. By observing the position of the needle on the scale, which is divided in the same divisions as the graph, “Lean,” “Economy,” “Normal,” “Power,” and “Rich,” the loss of Fuel in the example above can be shown accurately and compared with the Power loss. This valuable information can be gained as well while the car is travelling along the road as it can in the garage. Indeed, it is always advisable to take readings under both conditions to secure the best carburettor adjustment for each car. The Analyzer is complete in every way, and needs no upkeep costs to maintain it in perfect working condition. It is an essential instrument for every modern garage and completes the testing equipment of those who specialise in accurate and scientific demonstrations for their own and their customers’ satisfaction. The Advantages of Exhaust Gas Analysis To the Garage. The majority of motorists are keenly interested in the number of miles their car runs to the gallon and are therefore deeply impressed if it can be demonstrated exactly how their carburettor is performing. With the Lantz Exhaust Gas Analyzer the motorist can be shown the reading on the dial before and after adjusting the carburettor and these readings can be explained by means of the graph opposite. Subsequent running will confirm the tale told by the Analyzer, by means of the saving of petrol which will result. The Lantz Exhaust Gas Analyzer enables the garage to diagnose faulty carburation and to demonstrate to the customer that the fault has been corrected. It shows that the nearest approach to perfect combustion has been attained, and informs him of the consequent gain in petrol consumption, proving that the loss of power is negligible when compared with the saving of fuel. It is seldom that such a clear and easily worked demonstration is available to the garage Proprietor, winning, as it does, the complete confidence of the customer in the ability of the garage to detect and correct scientifically a fault that has hitherto been dealt with by approximation alone. No opportunity should be lost of capitalising this striking demonstration. To the Fleet Owner. Petrol economy is of great importance to all fleet owners, and the Lantz Exhaust Gas Analyzer is undoubtedly the best means of reducing fuel loss to the minimum, by correctly analysing the carburation of each vehicle at regular intervals. The petrol bill can be greatly reduced by making certain that the greatest degree of power is produced for the least expenditure in fuel. Apart from economising in fuel, correct carburation lowers maintenance costs by eliminating excess sooting and the dilution of the oil by free petrol, thereby saving wear and overhaul costs. Chart Text: Top Axis: COMPLETENESS OF COMBUSTION % Left Axis: % POWER LOSS, EXCESS AIR - VALVES WARP OR BURN Bottom Axis: AIR-FUEL RATIO, LEAN, ECONOMY, NORMAL, POWER, RICH Diagonal Lines: CARBON DIOXIDE, CARBON MONOXIDE Curved Line: FUEL LOSS % Caption below chart: “LEAN, ECONOMY, NORMAL, POWER” and “RICH” correspond to markings on the Galvanometer. The Arrows from the centre of the power area on the above Chart give an example of the use of the Chart in interpreting the reading on the Galvanometer. Table Title: Air Fuel Ratio—Gas Equivalent, % Completeness of Combustion Table Data: Air-fuel Ratio. | Completeness of Combustion. % | Composition of Exhaust Gas. % | CO₂ | O₂ | CO | CH₄ | H₂ | N₂ 9.0 | 50 | 5.7 | 0 | 13.0 | 1.7 | 7.0 | 71.5 9.6 | 53 | 5.9 | 1.0 | 12.8 | 1.4 | 6.5 | 72.4 10.1 | 55 | 6.7 | 1.0 | 11.2 | 1.4 | 5.8 | 73.9 10.6 | 57 | 7.5 | 1.2 | 9.8 | 1.4 | 4.8 | 75.3 11.0 | 62 | 8.2 | 0.8 | 8.9 | 1.1 | 4.4 | 76.6 11.5 | 67 | 8.9 | 0.7 | 8.0 | 0.8 | 3.9 | 77.7 12.0 | 71 | 9.4 | 0.6 | 7.0 | 0.7 | 3.2 | 79.1 12.6 | 75 | 10.4 | 0.9 | 5.0 | 0.7 | 2.4 | 80.6 13.1 | 78 | 10.7 | 0.9 | 4.6 | 0.8 | 1.6 | 81.4 13.5 | 81 | 11.5 | 0.6 | 3.8 | 0.6 | 1.3 | 82.2 13.9 | 87 | 12.9 | 0.3 | 1.9 | 0.4 | 0.8 | 83.7 14.5 | 95 | 13.4 | 1.1 | 1.2 | 0.1 | 0.2 | 84.0 Product Information: Exhaust Gas Analyzer . . . Price £12-12-0 Nett Trade With chromium Faceplate, coloured dial, black crackle finish body, complete with all fittings, and suitable for both 6 and 12 volt batteries | ||