I want to install an engine in a inverted position. Most people tell me it is NOT good for the engine, however many designs use this setup (most pattern planes have it). WHAT is TRUTH and what is FICTION?

Do some type of engines run better inverted than others?

Most if not all engines run very well inverted. Some require that the idle be set slightly leaner, all require that you be careful not to flood the engine while priming it. Best starting procedure is to invert the plane while starting.

You won't damage the engine but they can be more troublesome to tune, mainly the low end. I have done it before with no problems.

I've seen several planes lately that were obviously designed for a inverted two stroke to have a side mounted four stroke. Seems like it works out pretty well as far as what to do with the muffler? Also engines on their side are not as troublesome as the inverted ones.

I see one guy at the field with an inverted Saito 180, closes his high speed needle and opens it as he starts the engine. He has a L-shapped wire in it and keeps up with where the right position is. He makes it work and seems to have no trouble.

enjoy,
Jim

I have an OS FS-70 II mounted inverted and have had no problem with it. You just have to turn the engine over a few times by hand before trying to start it to make sure there is no hydraulic lock.

Most problems occur because there is a siphoning effect into the carb when the tank is full. At higher rpm it is not a problem, however This makes consistent smooth idle tough, especially low idle ! If you place the tank lower than normal in the fuse, this will help eliminate this problem but it will create others!

some engines seem to do very well mounted inverted while others can be a real pain!! Best thing to do is set it up on a bench first and see what you got ! you can always add on-board glow but this will add $, weight and complexity to the project !

80% of my engine are mounted upside down, the other 20% are with the head at 5 o'clock, if you can adjust an engine, you will have NO problem at all......if on the other end you cannot adjust an engine upright yet....well it won't run any better upside down.

Daniel D.

THNX you all, inverted engine it will be!