Some Engines Thoughts and Questions


| January/February 1974



Heinricci Hot-Air Engine

Courtesy of George S. Clark, 254 Pond Point Avenue, Mil ford, Connecticut 06460.

George S. Clark

603 Fremont Street, Middleville, Michigan 49333

Nearly 50 years ago I was employed by a road contractor to operate an Allis-Chalmers 10-18 (see page 11, May-June GEM and 12, Tractor Operating and Directory). Was rather surprised to note there were any of these still around. This was a so-called all fuel tractor, and had a double bowl carburetor, so one could switch from one fuel to another instantly. It had a Wilcox-Bennett centrifugal type of air cleaner. The motor was of the 2 cylinder opposed type. The manifold hot spots were adjacent to where the fuel entered the cylinders. Carburetor was right next to the rear cylinder, leaving a rather long un-heated portion to carry the fuel mixture to the front cylinder. That part always ran cool, and fuel condensed in it, so we always had trouble keeping the front cylinder firing and working properly. We mixed gasoline and kerosene, half and half for fuel.

Here is a type of engine that apparently did not work out very well, in recent years I have never heard more of it. It was used to propel an automobile shortly after the turn of the century.

The compound, built by the Eisenhut Horseless Vehicle Company, of Middletown, Ohio, had an internal combustion engine with two high pressure and two low pressure cylinders. Exhaust from the high pressure cylinders, passed to the low pressure cylinders, where the gas did more work by further expansion, before passing into the atmosphere. Since the exhaust was at low pressure, it caused less noise than the ordinary engine. This company was in business only from 1903 through 1907 before going bankrupt. Apparently, the compound principle did not work as expected in the case of an internal combustion engine, does anyone know of any modern manufacturer who uses anything of this sort?

There are some things about the 'Wankel' engine that I can't help wondering about. The seals or blades in the rotors are single and amount to about the same as one ring on each piston. The angle of contact with the chamber varies widely. It would seem possible that there might be some chattering at some angles. Operating at a very high speed the centrifugal force on them would be considerable, speeding up wear. Also due to the method of lubrication (mixing oil and gas) would not the exhaust be likely to contain more hydrocarbons than that of an ordinary 4-cycle motor? Yes, I know it acts as a 4-cycle motor, but the lubrication of these rotors and seals must be accomplished by adding oil to the gas. In the past I've read in the mechanical magazines of many 'Revolutionary' engines and none of them have ever appeared on the market. The Wankel however does seem to have found some application in some foreign cars, as well as snow-mobiles, out-board motors, etc. I understand it's efficiency isn't quite as high as a good regular motor and with all the accessories to combat smog will be still lower. I for one really doubt if it will ever completely replace the piston engine, particularly the Diesel which I believe more car manufacturers should be looking into. The Diesel operates at maximum compression and efficiency regardless of load, while the ordinary automobile engine does not reach full, or anywhere near, the rated compression except at wide open throttle under heavy load.

The Stirling type of engine, as I understand it is a type of external combustion engine which preceded the modern internal combustion engine by a number of years, originally developed in the British Isles I believe. For operation, it is dependent on the expansion and contraction of entrapped air which is alternately exposed to heat and cold. I understand the original ones had trouble from the heated end of the chamber burning out prematurely. This however may have been overcome in more recent years. Though as pictured it would be double acting, with alternate vacuum and pressure on the power piston, would the power impulses on the power piston be equal? The maximum amount of suction attainable would be 14.7 lbs per square inch, while that might be exceeded greatly on expansion.