A month and a half ago we did a feature titled, A Brewer’s Pair of Speedwells and an Electric Car in Dayton, Ohio. In that article a circa 1910 Speedwell touring car, and a 1914 touring car with a rotary valve engine were featured. While conducting research for that post the very interesting illustration of the 1912 Cruiser (above) was found in the Motor along with a technical article (below) in the Horseless Age covering the new 1914 rotary valve six.
The Cruiser was only one of several unusual body styles that Speedwell offered in addition to a fairly normal line of conventional coachwork. This sinister looking touring car brings to mind of the US Navy armored cruiser warships that were being produced at the time. The high-sided and close-coupled touring car with a sharply angled cowl and hood also featured an unusual trunk. This offbeat design was on a standard chassis with a longer 132-inch w.b., powered by a 5 x 5-inch bore and stroke 50 h.p. engine that displaced 393 c.i.
- 1914 Speedwell rotary valve six power plant.
The teens were also a time of experimentation by a number of automakers trying to improve upon the conventional poppet valves used in nearly all engines at the time. The root of the problem was the steel alloys used for manufacturing valves were still in the early stages of development. Not being durable enough for the job, valve grinding was needed as often as every 2500-5000 miles.
The two different types of engine designs soon appeared on the scene in an effort to overcome this problem. The Knight sleeve valve engine was developed by Charles Knight (1905). It was soon followed by the rotary valve engine design that was used as early as the 1850s in the Corliss steam engine. This design appears to have been first used in an internal combustion engine (1911) built for aircraft use by the National Engine Company Ltd. of the UK. It was soon followed in Italy by Italia (1912), which may have been the first automaker to manufacture the design.
Speedwell chose a complicated dual rotary valve hemi-head design. Three illustrations and the text from the March 25, 1914 Horseless Age are reproduced here that show and describe how the automaker constructed its engine. The novel new engine design, unfortunately, was not enough to save the Dayton, Ohio Company. The combination of the factory being inundated by the Great Dayton Flood of 1913 and the costs involved to develop and manufacture the new engine caused the Speedwell to enter receivership soon after and cease operations in 1915.
- One of the six valve units used in the engine can be seen (above) at the top. Each individual unit for a cylinder consisted of a key like “valve” sealed on each side by rings that used the same design as the piston ring. This type of design suffered due to wear leading to a loss of compression and servicing issues.
- The complicated gear drive (above) for the dual valve shafts, which is not entirely clear in this image. The silent chain on the left-hand side connects the starter to the crankshaft. The text (below) from the “Horseless Age” describes how it was manufactured and its operation and inspection.