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).
Visit to Mc Evoy Superchargers, detailing their products, contracts, and a comparison with the Zoller blower.
| Identifier | ExFiles\Box 140\1\ scan0136 | |
| Date | 25th February 1935 | |
| +109 TO MR. E.H. Copy to MR. Hs.{Lord Ernest Hives - Chair} Hives. Mc Evoy Superchargers. On Saturday I went round their Derby Works with a friend who is having one fitted to his car. They are installing a huge amount of brand new modern machinery, large boring and milling machines, single and multi-spindle drilling machines, grinding machines, and two automatics. They appear to have fixed up a contract with M.G.s, who will shortly announce a model with a blower provided by Mc Evoy, and they expect to fix up also shortly with Singers, S.S. and Daimlers and are making two 34-litre blowers for a high altitude attempt on an aero engine. He said that he was going to spend Sunday in the Peak testing the supercharged Daimler, and that Daimlers were very pleased with it and thought they had stolen a march on us. I said I thought their march was yet to come. Mc Evoy is making a little better job of the installation now, and has them under the bonnet, at the side or on top of the engine, and usually driven by enclosed chains. The M.G. is at the top on one side, and feeds straight down into the induction pipe, from an updraught carburetter. The Singer has it cast in one with the rocker cover, driven by a chain at the front from the chain camshaft drive. Blowers and carburetters stuck out in front of engines only worked in the summer apparently. He took us out in an S.S. which had the blower under the exhaust manifold on the near side. It seemed quite lively and smooth, and could only be heard a little on the overrun. The Zoller blower he uses is a little better than the Powerplus, but in my opinion still has nothing on the Roots for reliability and simplicity. The blades do not run round inside a sleeve, as in the Powerplus, but are controlled from inside the rotating drum. The outer casing therefore is not quite cylindrical but is bored to a special profile traced out by the blades. The air does not have to pass into the inside of a rotating sleeve, and then out of it again. Thus the unit is more efficient volumetrically, and the ports can be arranged to give considerable pre-compression, and it is simpler and lighter than the Powerplus. However, it is out of balance, has its working surfaces lubricated with petrol, road dust and a little oil (the best grinding mixture), and can only be run at 3000 - 4000 R.P.M. owing to inertia loads on the bits. Other things he told us were that the M.G. racing cars for 1935 are going to be single-seaters with the Porsche system of independent suspension with torsion bars, as used on the German Auto-Union cars. Also that the German Government paid the Auto-Union concern £250,000 for five cars, with the stipulation that the engines would stand one hour's test all out at their rated maximum power. E/TSN. | ||