Above: right side view
Below: left side view



Cylinders: 3
Type: Inline, SOHC
Bore: 1.062”
Stroke: 0.875”
Displacement: .778 cu in/cyl x 3 = 2.334 cu. in.
Compression Ratio: 7.9:1
Ignition: Glow plug
Cooling: Air
Fuel: 15% nitromethane/methanol mix
Max. RPM: 12,000
Est. Horsepower: 2.5


Background -- This engine was designed to explore the smoothness and suitability of three cylinders with a single overhead bucket cam arrangement, a pretty simple valve layout. The main problem is getting large enough valves if you are using it as a racing engine. A half-century ago, Offenhauser tried this scheme with a 91 cu.in. midget racing engine and built a couple of them. The first one was quite sucessful but unfortunately, this was a time when midgets were going out of style and the development was dropped.

Construction -- One of the other reasons for three cylinders in my design is that there aren't too many duplicate parts to make. Because the original Perry model carburetors were not adequate, this engine uses three variable venturi carburetors of my own design. There were no castings used in this engine. Materials were mostly 6061 -T5 aluminum and 12-L1114 steel.

Operation -- This triple would turn up about 12,000 r.p.m. for a short period, which is hard on an engine with no load. The throttle response was almost instantaneous.


Detail of carburetors and throttle linkage.

(click on buttons)



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