It is Johnson Bros Motor Company that was established in Terre Haute, Indiana.

-By 1909 they made water-cooled, two-stroke engines with the architecture of four,  eight and twelve cylinders in V.

-These engines were called  "Aero". The four-cylinder in V, with 471 cu in of displacement gave 75 hp at 1,300 rpm.

-The eight-cylinder in V with 628 cu in of displacement gave 100 hp at the same rpm.

-And the twelve-cylinder that had a displacement of 942 cu in gave 150 hp at 1,300 rpm.

From Appendix 6: By 1911, the Johnson brothers made some V4 type aviation engine projects with 40, 60 and 80 hp, although they failed the Fed test. Gov. which discouraged its investors.

-They changed over to marine engines, and continued their designs where they became famous as Johnson Outboard Motors.

From Appendix 7: The manufacturer of light marine engines has also been in aviation and precisely in their beginning.

“A Johnson engine on the Shaw Flying Boat” (PiP-fmr)

-This 1915 engine, gave 90 hp and had a two-stroke cycle.

From Appendix 9: At the beginning of the previous century, starting in 1905, The Johnson Brothers made planes and engines to get the attention of the government. The engines were also known as Johnson "Aero".

-Having failed in this attempt, they dedicated themselves to marine motors  and started the famous Johnson Outboards brand.

“Johnson V4 Aero”

-“Aero” V engines of 4, 6, 8 and 12 cylinders were made. The V4 engines were made with powers of 40, 60 and 80 hp, for example.

-Photo sent by a collaborator. It seems to belong to Aerofiles.com.