Spur gear boxes are way too heavy for aircraft
use. For a given gear width a planetary is six times stronger.
The only reason the Allison V12 and the  Merlin V12 among other
WW II era water cooled V engines used them was to get the thrust
line higher. All radial aircraft engines used planetary and this
included the R4360 and the PT6.

Engineair has been out of business for several years as the Chevy
V8 has a limited life in aircraft use. Despite the use of all
aircraft quality parts in the engine such as rods, pistons, valves
and crankshaft. As far as I know every company that ever offered
a Chev based V8 aircraft engine for aircraft use is now out of
business and that includes Orenda. Read Smithsonian Air & Space
magazine article "Power Struggle" by Don Sherman, January 1997,
page 72. http://www.rotaryeng.net/DS-smith-art.pdf

There have been at least a dozen that have tried.

In order to get the EPI gear box to live in the Engineair installation
a very heavy flywheel was required.

See the attached pictures.


Paul Lamar