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).
Dynamometer testing of a Packard car for horsepower and fuel consumption, comparing its performance to their own designs.
| Identifier | ExFiles\Box 181\M11\ img036 | |
| Date | 25th May 1917 | |
| PACKARD & 7CA To EH. from R.{Sir Henry Royce} C. to J.{Mr Johnson W.M.} X.682 ORIGINAL (Stamp) Re "After-the-War" Chassis. D 1 X435 When the Packard was in Derby, I presume it was never put on the dynamometer, or I should have obtained a record [STAMP: RECEIVED] of the horse power. X3055. X2761 It has occurred to me that next time you get hold of this car, and any other car in which we are interested, it would be as well to find the horse power at various speeds until the engine shows a decided falling off in horse power. Then at say 30, 40 and 50 miles an hour a consumption test should be taken at full power of the engine, ½ power at the same speeds, and ¼ power, and if possible determine what power it absorbs to turn the engine round with the throttle closed. From these figures we should be able to find out the relative consumption of petrol of various cars more accurately than one could by road tests. We could also find out whether petrol could be saved by weakening the mixture. Again referring specially to the Packard, it will be noticed that it is very much lower geared than our engine, and should therefore pick up rather better and be better on hills. I have not so far noticed any very great superiority, although it is very good, but I rather have the impression that the engine soon over-runs itself and the maximum speed of the car is not at all fast, although the consumption is very great. This is what one would expect if the engine failed to fill up well. X.2651 I shall be glad to know how you are getting on with 7 CA, and whether any of the suggestions have shown any advantage. I am quite willing to test the lighter axle, but agree that it cannot show very much advantage if the weight is very largely in the wheels and brake drums. FHR R.{Sir Henry Royce} | ||