A Brief Word

| March/April 1991

Recently we were looking through the 1903 issues of Gas Power Magazine. In the very first issue is an advertisement for the Port Huron Gas & Gasoline Engines, as built by Port Huron Engine & Thresher Co., Port Huron, Michigan. The Port Huron engine is listed on page 397 of American Gas Engines, and supposedly was available in sizes from 2? to 50 horsepower. Are there any of these engines left?

The June 1903 issue of Gas Power also carries an article on hot tube ignition. The following is an extract of that article:

The principle which underlies such ignition is that in compressing a charge it heats. Bearing this in mind, suppose that the charge entering the cylinder comes in contact with surfaces nearly, but not quite hot enough to set the mixture afire. When the mixture is compressed, this raises the temperature. If compression is high enough, the charge will self-ignite. Of course, all of this happens in a fraction of a second.

If the igniting surface of the hot tube is just hot enough the mixture will not ignite until the piston comes up to top dead center. With this delayed ignition, the engine will not run very fast. If the tube is too hot, the mixture will fire too soon.

With a short tube, a dull cherry red will be satisfactory for a gasoline engine working on fairly high compression. If the tube is long, or if the passage between the tube and the cylinder is long, the tube must be hotter to run at the same speed as with a short tube.

Ordinary street gas ignites much more suddenly than gasoline vapor, and it is much more difficult to run a hot tube engine on gasoline than on street gas.