Above: right side view
Below: left side view



Cylinders: 2
Type: Inline twin DOHC
Bore: 1.062”
Stroke: 1.00”
Displacement: .889 cu in/cyl x 2 + 1.78 cu in
Compression Ratio: 6.84:1
Ignition: initially coil/spark plug; later glow plug
Cooling: Air
Fuel: 15% nitromethane/methanol mix
Max. RPM: 12,500
Est: Horsepower: 2.2


Background -- I've long been interested in the overhead cam engines used by Harry Miller back in the early racecars starting around 1915. These engines became winners for many years at many tracks, including Indianapolis. After Miller went broke, Fred Offenhauser, Miller's shop superintendent, bought the business and was very successful for many years. These "Offy" engines were comparatively simple but very rugged. Development continued until the last successful Offy fours could put out 1200 H.P. from approx. 221 cu. in.

Construction -- Building an Offy-style engine intrigued me, but I didn’t want to have to make four cylinders and the associated parts. The engine I finally designed was two cylinders with head attached to the cylinder by six bolts.
The crankcase was hogged out of solid stock but the engine mounts were attached by welding. At the time I built this engine I was still using spark plugs. Later on I eliminated them and used glow plugs on the engine. Timing belt drive plus one 2/1 gear off the crankshaft actuates bucket-type overhead cams. A pair of model engine carburetors were used, but have been difficult to adjust.

Another feature of this engine was taken from the Triumph motorcycle engines. This was a three-piece, single throw crankshaft with a center, internal flywheel.

Operation -- This engine ran okay initially but later it was found almost impossible to hold this crankshaft in alignment. Finally, I broke down and built a solid, one-piece crank shaft. Although very difficult to make, this has worked well. Later runs were made with glow plugs and were quite sucessful. It would turn up over 11,000 R.P.M. with almost instant acceleration.

At this writing, the engine is being hopped up; the original carburetors are being replaced with ones of my own design which have worked nicely on other engines.




Detail of camshaft drivetrain.

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