Building an Otto-Langen Atmospheric Engine -With a Little Help from the Curbside Parts Supply

| December/January 2002

I had just finished my 'VBS Engine' (see GEM, June 2001) and was looking for another engine project, but it had to be an unusual engine. The Otto-Langen atmospheric engine of 1864 had always interested me, but I had never seen one.

Wayne Grenning's Web site (http://members., had a revised edition of his February 1991 Gas Engine Magazine article, which was my main source of information on this early engine.

The Otto-Langen engine was the first internal combustion engine to go into production, and from 1864 to 1876 about 4,000 engines were built using a free piston design. The power of these early giants was low and the engines were big: A 2 HP engine weighed about two tons. Low horsepower seemed great for a home-built engine, so I put Nicolaus Otto's design on a diet and introduce some new engine components.

My home-built engine wasn't going to be a scale model (Wayne Grenning already offers excellent Otto-Langen models), just a home-built engine put together with junk. I didn't bother to make formal drawings or even a sketch, as that might have restricted me since my intention was to use available parts and materials in building this engine. The only power tools used on this project were a drill press, belt sander and 3/8-inch electric drill. Mo welding, lathe turning or milling was required.

Sourcing Parts

The engine is mounted to a discarded lawn mower frame turned upside down.

My first stop for parts was R&S Performance in Orlando, Fla. Scooter and Big Daddy, the moving forces behind R&S, make a living by repairing and maintaining air-cooled Volkswagens (VW) but live to build and drag-race Volkswagen-powered cars. My initial shopping list was a later model VW, 1,600 cc dual-port head and cylinder, which were easy to find in their scrap pile. I cut the head in half, modified the valve spring retainers to operate with very weak springs and made a progressive rocker arm assembly, using two door hinges to sequentially open the valves using one push rod (actually, my inverted engine uses a 'pull rod,' not a push rod). A small piece of foam rubber saturated with oil and wrapped around the valve stems provides lubrication. I wasn't sure how big the combustion chamber should be for this low-efficiency engine, so I extended the 85.5 mm cylinder with a 90.5 mm cylinder. I drove the two cylinders together, skirt-to-skirt (a VW cylinder has a protruding skirt that mates to the engine case), and sealed the surface between the two cylinders with a copper head gasket and flat gasket material cemented between the two cylinders. I was beginning to realize that each step of this home-built engine would be a 'science project,' and workable solutions would have to be determined before proceeding to the next issue.