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Mac Sine, 9025 Phoebe Court, Annan dale, Virginia 22003, recently wrote to GEM, saying, 'During 1988, among the many topics that appeared in the 'Reflections' column were Lauson engines and Dr. Alfred Buchi and Turbocharging. I would like to make the following comments regarding these subjects.

Lauson engines are represented by the following photographs: 23/5/23 and 23/8/21. I have had a special interest in Lauson engines of all ages and models from the beginning of my interest in engines and over the years have managed to compile a fairly complete collection of Lauson literature spanning from approximately 1910 through the 1950's. I also have number of actual Lausons from the various model groups built through the 1950's.

Over the years I have had good rapport with people at Tecumseh Products Company (Lauson's parent since 1956); as far as anyone knows, pre-Tecumseh serial number lists or production records no longer exist. I can provide approximate manufacturing dates by comparison with some of my dated literature. Key points on the spoke flywheel models are the model or casting letter(s) along with the horsepower rating, the ignition sys tem, style of carburetor and whether or not the engine has a cast full-length crankcase cover. Key points on the disc flywheel models are the type of ignition, location of spark plug, type of crankcase cover and type of teeth on timing gears. All other air and water cooled models are fairly easy to approximately date.

Another dating clue is how the company name is listed on the name-plate. Prior to approximately 1932, the name was John Lauson Manufacturing Company. From about 1932 through 1936 the name was Lauson Corporation, and from approximately 1936 through 1941 the name was Lauson Company.

There seems to have been some sort of transitional phase with some of the earliest high speed air and water cooled models receiving John Lauson nameplates. Engines produced during Hart-Carter Company's ownership of Lauson (1941-1956) still said Lauson Company on the nameplate and, excluding inboard marine engines and outboard motors, continued to end model designations with the letter C. Following Tecumseh's purchase of the company and subsequent updating of the product line the ending model letter was changed to an H.

The March/April 1975 issue of GEM carried my article 'Lauson Engines, Their History and Development', in which I reviewed Lauson engines produced until Tecumseh's acquisition of the company. Since then I have not uncovered any additional information which would war rant revision of my original 'guesstimates' of production dates.

The standard base color of the spoke flywheel models is given as Brewster Green; this corresponds to a DuPont Dulux code of 24166. Many of the spoke flywheel models appear in the catalogs with striping on the engine and skids or cart frames but the color of the striping is not described. Color of the skids or cart frames is also not given but I do have one skid set with traces of what appears to be an original red color. Most of the disc flywheel models were also painted Brewster Green. Lauson engines produced for the DeLaval Dairy Supply Company, which were sold under the Alpha name, were also painted Brewster Green. Disc flywheel engines produced for the Lansing (cement mixer) Company were painted grey. I beleive that the VW-series milking machine engines were also issued in Brewster Green. Color of the other high speed air and water cooled models was dictated by customer order.

I am certainly willing to correspond with people seeking information about Lauson engines. I am presently on a job project in Utah, but my files are home in Virginia (mail is forwarded to me), so my response time could be lengthy depending on whether I can answer from memory, or would have to wait to review my files.

On Dr. Alfred Buchi: Dr. Buchi is best known for his development of the pulse, or 'Buchi' type of exhaust turbocharging system.

The turbocharging system with which most people are familiar is the constant pressure system. With this sys tem, all of the engine's exhaust ports are connected to a common exhaust manifold which leads into the turbo-charger exhaust turbine. When the engine is running the pressure in the manifold and at each cylinder's exhaust port is essentially constant.

With the pulse turbocharging system, the exhaust manifolding is divided among the engine's cylinders with certain cylinders sharing certain manifold sections. The sections lead into the turbocharger exhaust turbine. Generally, each section is limited to three properly 'spaced' cylinders. Cylinder spacing is deter mined by crankpin angle, number of cylinders and firing order. A divided exhaust manifold insures that the pressure in the manifold at each cylinder's exhaust port is lower than if a single manifold were used.

As an exhaust pulse travels through the manifold runner a lower pressure area is formed behind it. This lower pressure area allows cylinder scavenging (valve overlap period on four-stroke-cycle engines) as the pressure in the exhaust manifold becomes lower than inlet manifold pressure. Dividing the exhaust manifold according to cylinder 'spacing' insures that the exhaust pulse leaving a given cylinder will not interfere with the scavenging of other cylinders on that section.

Comparing two otherwise identical engines having the same intake manifold pressure, the pulse turbocharged engine will have a greater pressure differential across the cylinder during the scavenging period than the constant pressure turbocharged engine.

The Ingersoll-Rand Engine-Process Compressor Division (now part of Dresser-Rand Company) was the first engine builder to apply pulse turbocharging to a spark ignited gas fueled engine with the introduction, in 1945, of the model KVS. Today, Dresser-Rand offers four-stroke-cycle gas engines with both types of turbocharging systems although emphasis is on refining state of the art lean-burn constant pressure turbo charged engines that develop a more economical fuel rate than the pulse turbocharged engines.'