The name Glen Curtiss is slowly slipping into the darkness of history as things often do but as hardcore gear heads we’re going to do everything we can to keep it fresh. Curtiss is one of the great mechanical minds of the 20th century and lots of the development in internal combustion engines, especially those that were used in airplanes. One of his engines, the OX-5 of which 12,000 were produced from 1915-through the end of the teens when it was supplanted by stuff that was more advanced, powerful, and light.
The OX-5 was not the best engine that Curtiss ever built but it was one of the coolest in our opinion. The basic design began in the early 1900s as a V-twin and then more and more pairs of cylinders were added until the V8 was achieved over the years. Displacing 500ci and making about 90hp it is by no means a barn burner but it was simple, easy to service, and as compared to other stuff of the era pretty reliable. If you think flying sucks today, imagine going up and having no idea if the engine was going to kill itself when you were in the clouds.
The buy it now price on this thing is $14,000 and the engine is currently in Brazil. That’s a far cry from the $20.00 that guys were paying in the 1920s for rebuilt or replacement engines that bolted into their JN-4 “Jenny” planes. The Jenny was a crazily successful aircraft that was used for all kinds of yeoman work. It obviously didn’t get anywhere quickly with 90hp but they sold in huge volume for their day and the vast majority of them had OX-5 power. Believe it or not, these engines are more likely to be found in restored or recreated Victorian era race cars by gear heads these days. The Jenny was such a workhorse it suffered the fate that heavy trucks do. They get used to the end and scrapped. Not many exist.
On the stats side. 4.5:1 compression, 4″ bore and 5″ stroke, a dry weight of 390lbs, and a gear driven oil pump that was supposed to produce 40-60psi of pressure. The engine could make 105hp for short periods if the wicks were turned all the way up but apparently that was for emergencies only and not for sustained use.
This is a really cool old engine that would look freakin’ amazing in the front end of a t-bucket. Sure it would be slow but boy would it be unique!
Check out the photos and then see more at the link below them!
That is some bizarre valve actuation arrangement, the intake appearing to be pulled down via a sleeve around the push-up exhaust rod, both rockers in the hemi-style layout sharing a pivot. I’d like to see how that worked down at the cam. That’d look cool in an Edwardian-era race car as well…:)
I recall a story from some time back, the owner of a bi-plane was telling me how he traveled around an hour-at-a-time, having to land and squirt oil on his valvetrain and then take off for another hop. I was more interested in his old car collection and wasn’t paying much attention but wish I had…what are the chances it was one of these motors in there?
The Smithsonian has the motorcycle that Glen built and used as a test sled for his engines. On accident, he set a land speed record when he got to the forth pair of cylinders. Direct, open shaft drive and only the whisper of brakes must have made for a fun ride!
Get that thing in a JN-4 “Jenny” post haste!
couple of vids of an ox5 installed in a car. Chain drive and tyre smoke!
https://www.youtube.com/watch?v=bkUL649iNoo
https://www.youtube.com/watch?v=q7fg3ena88k