Great Plains Aircraft modifies and commercializes horizontally-opposed, 4 cylinder VW engines. Except the Half VW, which has 2 cylinders.

“Type 1”

-The Type 1 is the 1600 cc engine with 4 horizontally-opposed cylinders giving 55 HP at 3,600 rpm. It uses simple ignition by Slick magneto, and has a direct output to the propeller.

“With toothed belt reduction gear”

-There are three reduction ratios: 2 to 1, 1'6 to 1, and 1'3 to 1.

-The "up-grade" version for the 1,600 cc is the 1,835 cc. There is a conversion kit for this. It gives 65 hp.

-The 2180 cc major version of 1835 cc. The engines shown so far have a front output for the propeller. There is a version with the output at the Fly wheel side, or the rear, for which it uses a light cast iron cover and a bevel to avoid vibrations. It is in alignment with the extension of the shaft.

“Rear Drive model”

-The Type 4 has a displacement of 2400 cc, and gives 83 hp with a front oil radiator.

“Type 4 -2600”

-The ignition can be double, with the Bosch 009 system, the mentioned Slick magneto, by Compu-fir or Vertex magneto.

-A development of the 2400 Type 4 is the 2600.

-The power rises to 96 hp although the revolutions are lowered to 3,400 rpm.

-Through the "Carr" chapter we know the existence of Half-VW, a two-cylinder based on cutting the cylinder head in half, separating the cylinders on each side and using only one on each side.

-This is done on the same block of four cylinders, taking off the rear cylinders.

“Half VW cylinder heads”

-We can see the cut ends as well as the rocker covers and the thick welds to "close" the created openings.

-The Great Plains engines are designed to operate with a minimum octane of 100, that is, AVGAS 100LL.

From Appendix 10: This company works on Volkswagen engines, with 4 horizontally-opposed car cylinders, adapting them for VLA light aircraft, etc.

“The 2015 updated Half VW”

“The 4-2600, with belt reduction gear”