OS 46FX performance question  
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OS 46FX performance question - 3/15/2002 7:29:10 PM   
ZeroGravity


 

Posts: 28
Joined: 2/22/2002
From: philadelphia, PA, USA
Status: offline 		I have a 46FX that has been sitting on a shelf for about 4 years. The other day I took it apart and discovered some surface rust on the crankshaft and the rear bearing. I took it all apart and cleaned it all out with Chevron engine cleaner. Reassembled with all new gaskets. On the bench I get a peak of 12100rpms with 11x6 prop and 30% heli fuel. Is this whithin the normal performance level? During throttle down there is an audible noise, it almost sounds like one of the bearings is going on it. If the bearing was bad, would I get the 12100 rpms that I am getting? Should I install this engine in another plane or is there a chance it will detonate the bearing completely? If the bearings are bad does anyone have any idea what boca replacements would cost?
       Post #: 1

OS 46FX performance question - 3/15/2002 9:16:09 PM   
PaulSwany



Posts: 4792
Joined: 12/7/2001
From: Bartlett, TN, USA
Status: offline 		My OS46 SF with Mac's tunned pipe pulls a 12.25 x 3.75 at about 13,500 rpm.... So my guess is that motor isn't puttin' out. If you hear a noise when it throttles down.. I'd pull it down and inspect the bearing races. look for side play and end play in the race... If you can wiggle the inner race around, the bearing is toast.... Boca bearings are probably the most expensive ones out there... but still not a bunch when considering the price of a new engine. I bought a set of bearing for my TT 46 from the dealer and I was out about $20....

(in reply to ZeroGravity)
       Post #: 2

OS 46FX performance question - 3/16/2002 6:24:30 AM   
bugsiegel



Posts: 568
Joined: 12/30/2001
From: brooklyn, NY, USA
Status: offline 		11/6 is alot of pitch. go get your self or borrow a 12.25/3.75 prop and see how close to the above rpm's you get. try an apc prop.

(in reply to ZeroGravity)
       Post #: 3

OS 46FX performance question - 3/16/2002 6:53:48 AM   
Jazzy



Posts: 1097
Joined: 1/8/2002
From: Erie, PA, USA
Status: offline 		Zero, I had an engine sitting idle for only about a year and it made the same clacking noise. When I first ran my Magnum 1.08 it did it too. I came to realize, with the magnum, it wasn't the bearings but a little play in the con rod. You might want to check that too. If the steel pins oxidized at the ends of the rod it might cause enough play to make the same noise.

Jeff

(in reply to ZeroGravity)
       Post #: 4

OS 46FX performance question - 3/16/2002 7:09:14 AM   
THE TAILBACKER


 

Posts: 139
Joined: 3/2/2002
From: New Mexico
Status: offline 		Yall gut to mutch prop der boa! Throw on a 10/7ish. I get around 13,800-14. I also have one with a 9/7apc and a pipe turning 17,200.


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(in reply to ZeroGravity)
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OS 46FX performance question - 3/16/2002 8:12:39 AM   
Mighty Mouse-RCU



Posts: 597
Joined: 2/9/2002
From: Picayune, MS, USA
Status: offline 		Sounds about right for the size prop. Cant really say if it is too much prop, depends on what you want to accomplish with the engine and type of flying , type of plane. We fly with 11X5 APC. If your bearing are not too bad, they wont affect your rpms much. Rest assured they will get worse. Suggest you look at them real close. Check the front first, when I lost mine, the front is the one that went. But it could be either or both.

(in reply to ZeroGravity)
       Post #: 6

OS 46FX performance question - 3/16/2002 4:06:00 PM   
MikeL



Posts: 2335
Joined: 3/8/2002
From: Bloomington, MN, USA
Status: offline 		That RPM is about right with an 11x6. Mine would turn right around that range with 15% fuel.

(in reply to ZeroGravity)
       Post #: 7

OS 46FX performance question - 3/17/2002 7:03:41 AM   
ramcharger


 

Posts: 571
Joined: 1/25/2002
From: St Louis, MO, USA
Status: offline 		I have a 4+ year old OS 46FX and always run a 11x6 MAS prop and get 13,000 rpm with a baffleless muffler, 10% Cool Power, and OS #8 plug. With a 11x6 APC 12,700 to 12,800. In cool weather I sometimes get a hundred more rpm wit either prop. This engine has never been wrecked or suffered a hard landing but it has hundreds and hundreds of flights.

(in reply to ZeroGravity)
       Post #: 8

OS .46FX RPM's - 3/17/2002 7:45:41 AM   
Thud_Driver



Posts: 965
Joined: 12/29/2001
From: Victorville, CA,
Status: offline 		The AT-6 racers out here are using the OS .46FX as the standard engine with an 11x7 Master Airscrew mandatory. I've personally tached 4 of these engines with 3 different tach's. RPM's were always 13 - 13.5K. Was really annoying because I can't get my .60's to turn the same prop that good.

The older .46FX's are known to have a peeling problem with the chrome separating from the inner wall of the cylinder. I took a friend's engine apart, which he said wasn't running right, and sure enough, about 80% of the plating was gone. might check it and see if peeling has started.
The rust, particularly since you cleaned it up, generally won't hold the engine back unless the bearings have had pieces flake off. They will feel rough when turning them with your fingers if so. You probably can't feel it just by turning the shaft.

Your engine isn't that bad yet, but it also isn't up to what I'm used to seeing.

The guys recommending the large diameter low pitch props are into a certain flying style which emphasizes climb performance, acceleration & hover versus speed / typical sport type flying. Go there if you want, I don't care for it.

(in reply to ZeroGravity)
       Post #: 9

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