The Internet Craftsmanship Museum Presents:

George Luhrs

March 1, 1941— February 2, 2014

Joe Martin Foundation "Metalworking Craftsman of the Year" award winner for 2001

Builder of the "world's smallest" internal combustion engines

George Luhrs spent his working life as a professional machinist running his own business before retirement. He did aerospace and R&D work that required great precision. Now he finds challenge in building the world's smallest running internal combustion engines.

About George Luhrs

Among George's credits are wins in the 2000 and 2001 Sherline Machinist's Challenge contests at the NAMES show in Michigan. He was also awarded the Joe Martin Foundation award for "Metalworking Craftsman of the Year" for 2001. The following biographical information was provided by George Luhrs and his wife, Barbara. 

We regret to announce that George passed away February 2, 2014. This page will continue to honor his life and his work as the master of the world's smallest ignition internal combustion engines.

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George Luhrs has been building engines of all sizes for most of his life. As a kid, he worked on all kinds of models, including free flight and "U-control" airplanes, model boats and model cars. He fixed and rebuilt small engines and, as a teen, worked on cars. In order to do these things, he learned how to use many tools, including the machine shop equipment needed to make and repair parts.

George worked his way through school in a machine shop. His education consisted of a degree in mechanical technology, which prepared him to be a metallurgist, a tool and die designer, draftsman, machine tool operator and mechanical engineer, all of which he has used both in his business and with his hobbies.

Soon after he graduated, George decided to set up shop in his own basement. For over 35 years until he retired 2 years ago, he was self-employed in the machine shop industry. At first he manufactured parts for aerospace corporations, and then did design and research and development work for several private firms. He has also designed and built unique machinery for a few local companies. He considers himself fortunate to have been able to earn his livelihood doing what he enjoys most.

Over the years, when his shop machines were not tied up with customer work, George would build models of engines and also many pieces of miniature apparatus, such as a drag saw, washing machine, cement mixer, water pump, grinder and others, to show how the engines were used. His hobby equipment consists of the same full-size industrial machinery that was used for the machine shop business. He designed and built all his own specialized tooling used to make the parts for his model engines. This includes gear cutting, miniature bolt making and special cutters.

George has had several specific goals in mind over the years. One is to build running gas engines smaller and smaller. Both their size and getting them to run reliably is a challenge, and that challenge is what keeps his interest. Each time he has achieved a goal in one size, he tries to make the next one even smaller.

The smallest engine he has designed and scratch built so far is a 1/8" bore, 5/32" stroke, single cylinder, four cycle, overhead valve, sparkplug ignition engine. It runs, but he is still trying to get this one to run as well as all the others. The four cylinder, four cycle ignition engine which won first place in the Sherline Machinist’s Challenge at the N.A.M.E.S. show in 2000 was designed and built from scratch.  It took over 600 hours to complete. For the 2001 contest, George switched to a radial design and created a 5-cylinder aircraft engine with 1/4" bore and stroke which took first place for the second year in a row.

Until the 2000 contest, all the engines George had designed and built were single cylinder, four cycle engines. For that contest his challenge was to build a small multi-cylinder four-cycle engine and have it run reliably. Next year's 5-cylinder radial expanded his range even further. All his engines are overhead valve sparkplug ignition engines. They all run using homemade coils for make-and-break ignition and miniature model airplane type coils to fire the sparkplugs. These are mounted in battery boxes or in the base of each engine so as not to distract from the engine itself. The sparkplugs he makes for these engines range in size from ¼-32 thread for the large engines, 6-40 thread for the mid-size ones and 2-64 or 0-80 threads for the smallest engines.  

George accepts his plaque and check from Joe Martin Foundation representative Craig Libuse for being selected as the "Metalworking Craftsman of the Year" for 2001.

George’s other goal is to show that there are still people who make things from scratch; that is, no kits and no castings. Most importantly, he wishes to promote model building as a hobby to the younger generation by passing along as much knowledge as he can to anyone who is interested in learning. Toward this last objective, he has done a fair amount of work as a guest speaker to encourage interest in the hobby at his local grade school, the Boy Scouts, model airplane clubs and many live steam club meets. He also participates in numerous antique car shows each year and always displays his engines along with either a 1930 Pontiac or a 1960 Maserati. Many times the small engines generate more interest than the antique cars.

George has recently spent time tutoring a talented newcomer to model engine building named Jared Schoenly. When they first met, Jared was just ten years old, but he already had an incredible amount of knowledge of small engines. Over the past nine years he has spent time visiting my George and his wife to learn more about engines and get some hands-on experience in George’s shop. He has eagerly absorbed all George can teach him, and now at age 19 he is an honors mechanical engineering student at the University of Pittsburgh. He will soon be entering his own scratch-built engines in shows and contests and hopefully taking what George has been able to teach him to a new level. His parents also work to encourage the hobby and have put on the Cabin Fever Exposition in the Pennsylvania area for the past six years. The show is rapidly increasing in attendance, which is helping meet George’s goal of seeing new people enjoy the challenge of miniature machining.

George is seen as his show display booth with some of his engines and awards.

NOTE: Mr. Luhrs’ models have been featured in many magazines including Strictly I.C., Modeltec, Fine Scale Modeler, Live Steam, Radio/Controlled Model Cars and Great Scale Modeling. Photos of his projects can be seen on his web site at  

Here are photos of some of George's projects:

(Click photo for larger image.)

This single cylinder spark plug gas engine has a bore of 1/8" and a stroke of 5/32" and displaces only .0019 cubic inches. It was designed and built from scratch in 1996. Part of a penny can be seen at the bottom of the photo for size reference. (Thomas Oversluizen photo)
A close-up view of the single cylinder and carburetor. The external pushrods that operate the valves can also be seen. No one has yet challenged George's claim that this is the smallest running spark plug fired gas engine. By the way, it buzzes kind of like a bee when it is running.  (Thomas Oversluizen photo)
This four-cylinder inline aircraft engine won the 2000 Sherline Machinist's Challenge contest in Michigan. It is displayed on a laminated wood base with a matching laminated wood propeller. The display base is mounted to a glass covered case that displays all the components of a second engine.
This view shows the engine and display base without the display of individual components. The spark plug fired engine features a bore of 1/4" and a stroke of 5/16" for a displacement of .061 cubic inches. A quarter is used for size reference. (Thomas Oversluizen photo)
A side view of the engine gives a better idea of the fine worksmanship in each piece. Again, a quarter is shown for size reference. (Thomas Oversluizen photo)
The display base is shown here with the engine and laminated stand. Laid out in an orderly display are all the components needed to make up the engine. (Thomas Oversluizen photo)
Here is a second version of the engine George built to demonstrate its ability to actually run. A small fuel tank can be seen at the rear, and tiny throttle controls extend to the rear.
  George's winning entry in Sherline's 2001 contest displayed two 5-cylinder radial aircraft engines plus a third engine in parts in the glass covered frame behind. The running spark plug fired engines have a 1/4" bore and 1/4" stroke. A penny is used for size reference in the foreground.
A detail of one of the radial cylinders and head shows the external rods driving the rocker arms to operate the valves.
Another close-up of the engine shows the fine work in the laminated three-bladed wood propeller.
Yellow spark plug leads add a bright touch. Tiny throttle controls can be seen to the rear and below the bullet shaped fuel tank to which the engine is mounted.
Inside the glass covered display case are all the parts to make up a third engine. This close-up shows the level of perfection of each tiny part needed to make an engine this small actually run.
This small Stover hit-n-miss engine is another example of George's work. (Thomas Oversluizen photo)

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