OS 46 FX Mounting orientation and exaust question
12-24-2002, 05:35 PM
#1
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OS 46 FX Mounting orientation and exaust question
Hello!
I have a new OS 46 FX that I am breaking in prior to installing it on a Great Planes Ultra Sport + 40 that I am building.
I have run about 1 gallon of fuel through this engine and it is really starting to run really well!
It is getting close to the time where I am going to have to decide how to mount the engine and I'd like some feedback before I start drilling holes for engine mount bolts etc.
The plans for this kit call for mounting the engine upside down. Is there anything I need to know with respect to running this engine inverted?
The manual for this kit reccomends that a "Sport Scale" exaust be used as it will fit inside the cowl of my model. I've looked up this exaust, form what I can see, it has no muffler/expansion chamber at all. How would this affect the performance of the engine? Where I fly noise is really not a facto, so if it is louder than the stock exaust that is not a problem, but I do not want to sacrifice performance at all.
The other options are to use the stock exaust and have it hanging out of the cowl, or to mount the engine sideways and use a Pitts style exaust.
What are your thoughts on this?
I have a new OS 46 FX that I am breaking in prior to installing it on a Great Planes Ultra Sport + 40 that I am building.
I have run about 1 gallon of fuel through this engine and it is really starting to run really well!
It is getting close to the time where I am going to have to decide how to mount the engine and I'd like some feedback before I start drilling holes for engine mount bolts etc.
The plans for this kit call for mounting the engine upside down. Is there anything I need to know with respect to running this engine inverted?
The manual for this kit reccomends that a "Sport Scale" exaust be used as it will fit inside the cowl of my model. I've looked up this exaust, form what I can see, it has no muffler/expansion chamber at all. How would this affect the performance of the engine? Where I fly noise is really not a facto, so if it is louder than the stock exaust that is not a problem, but I do not want to sacrifice performance at all.
The other options are to use the stock exaust and have it hanging out of the cowl, or to mount the engine sideways and use a Pitts style exaust.
What are your thoughts on this?
12-24-2002, 05:43 PM
#2
My Feedback: (11)
OS 46 FX Mounting orientation and exaust question
David,
You can mount the engine any way you wish. It will work just fine.
With inverted installations, sometimes idle and acceleration can become problematic. The glow plug is at the bottom of the engine, then, and can act as a sump for liquid fuel at low throttle settings. This can make the idle erratic. The only cure in that case would be to add on-board ignition to keep the plug hot.
With different exhausts system types, the main thing would be to make sure the high-speed needle's adjusted correctly. This will change a bit from muffler to muffler. Some types may not give enough pressure to the tank to help you there. It's all try and see.
If you have room in the cowl, side mounting is usually the best compromise to hide the engine and get good running. It will run as well that way as if it were mounted in the upright position.
You can mount the engine any way you wish. It will work just fine.
With inverted installations, sometimes idle and acceleration can become problematic. The glow plug is at the bottom of the engine, then, and can act as a sump for liquid fuel at low throttle settings. This can make the idle erratic. The only cure in that case would be to add on-board ignition to keep the plug hot.
With different exhausts system types, the main thing would be to make sure the high-speed needle's adjusted correctly. This will change a bit from muffler to muffler. Some types may not give enough pressure to the tank to help you there. It's all try and see.
If you have room in the cowl, side mounting is usually the best compromise to hide the engine and get good running. It will run as well that way as if it were mounted in the upright position.
12-24-2002, 05:51 PM
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OS 46 FX Mounting orientation and exaust question
Thanks for your reply Bill, Merry Christmas by the way....
Do the stock exausts do anything to enhance performance? In my mind I think of them like the expansion chamber on my two-stroke dirt bike, which runs terribly if there is so much as a leak in the exaust, and won't run at all with the pipe removed. To me the "Sport Scale" exaust seems very much like an "open" exaust and so I am concerned.
Do the stock exausts do anything to enhance performance? In my mind I think of them like the expansion chamber on my two-stroke dirt bike, which runs terribly if there is so much as a leak in the exaust, and won't run at all with the pipe removed. To me the "Sport Scale" exaust seems very much like an "open" exaust and so I am concerned.
12-26-2002, 04:29 PM
#4
My Feedback: (11)
OS 46 FX Mounting orientation and exaust question
David,
The stock muffler doesn't enhance performance at all. It's intended to reduce the noise output of the engine. You can remove the baffle in the muffler, enlarge the outlet, or use an entirely different exhaust system. Many alternatives will help increase power by either reducing back pressure or tuning the exhaust system to the engine.
The stock muffler doesn't enhance performance at all. It's intended to reduce the noise output of the engine. You can remove the baffle in the muffler, enlarge the outlet, or use an entirely different exhaust system. Many alternatives will help increase power by either reducing back pressure or tuning the exhaust system to the engine.
