The Continental R-670

To power Buffalo LVTs the Continental W670-9A engine, otherwise know was the R-670 was used. It is an air-cooled 11 litre, seven-cylinder, four-cycle radial engine which first came into operation in 1934. The R-670 was primarily used for aircraft such as the PT Stearman PT-17, but was also used in a number of airship and light armoured vehicles such as the M2 Light Tank and T4 Combat Car in the 1930s and 1940s. At the time the advantage of radial engines was that they were air-cooled, so didn’t need all the water cooling apparatus which saved weight. This would of been great for planes they naturally got plenty of air, but for vehicles such as the Buffalo it would be very different. The greater power-to-weight ratio must have won though and would of been important for a vehicle such as the Buffalo that needs to float on the water. As technology advanced, more complex water cooled engines became more popular.

Continental Motors Company produced engines for a wide range of applications from the 1900s through to the 1960s. The Continental Aircraft Engine Company was formed in 1929 to develop and produce aircraft engines. The company has gone through a change of ownership a number of times but Continental Aerospace Technologies is still going in Alabama, United States.

See how a nine-cylinder radial engine works below, the seven cylinder R-670 would follow the same principles. Four-stroke radials such as the R-670 always have an odd number of cylinders per row, so that a consistent every-other-piston firing order can be maintained, providing smooth operation.

As time went on there were a number of variations to the R-670. The first version was rated at 215hp at 2000rpm and was said to be the lightest engine in it’s power class with dry weight of 425 pounds (192kg). The R-670 was more of an evolution than revolution as it was based on Continentals successful A-70 but with a number of refinements and larger bore creating a more powerful engine.

Between 1934 and 1936, Continental changed the factory designation for its radial engines from R-670 to W670 (also W-670) but they were for all sense and purposes the same engine. It was the W670-9A that was designed for use in military vehicles with larger front crankshaft journal and thrust bearing.

Our engine

The original engine.

After 75 years under the ground the original Buffalo engine was beyond restoration so a new engine one was sourced from Mississippi, USA in July 2021 and shipped to the UK. It is an original surplus LVT engine from the end of the Second World War and it’s believed that it hadn’t been run since it left the factory. The Buffalo engine team consisting of Chris Collop, Paddy Nightingale and Tom Woodhouse worked tirelessly to get it fired up and running as a static display.

See the new engine being run below at the Thorney Open Farm Weekend in June 2022.

It is hoped to get the new engine installed into the Buffalo in the future. Radial engines by their design have a higher risk of bursting into flames so for the safety of the operator a fire suppression system needs to be installed.

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