Volkswagen 1200 Specs: 77 x 64 mm (3.0315 x 2.5197 in)

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Volkswagen 1200 specs: 1.2L (72.7 ci) 4-cylinder, 77 x 64 mm (3.0315 x 2.5197 in) bore and stroke. OHV. Rod ratio and piston speed worked out.

The Volkswagen 1200 is oversquare — the 3.0315" bore exceeds the 2.5197" stroke by 20.3% — a layout that favors airflow and RPM over leverage at the crank. The 2.5197" stroke does not reach 4,000 ft/min of mean piston speed until about 9,500 RPM, so piston speed is not what limits this engine's revs — valvetrain and breathing are. Each of the 4 cylinders displaces 18.2 ci (298 cc).

It is one of 13 engines in the Air-cooled Flat Four family, sitting between the 69 ci and 96.6 ci members.

Dimensions

Displacement72.7 ci / 1.2 L
Bore3.0315"
Stroke2.5197"
Cylinders4
Bore/stroke ratio1.203

Construction

Block materialmagnesium alloy
Head materialaluminum
ValvetrainOHV
Fuel typegas

What these numbers mean

Bore/stroke character1.203 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves
Mean piston speed at 6,000 RPM2,520 ft/min — conservative for a street engine
Displacement per cylinder18.2 ci

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