West 50 + QJ500 muffler?  
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All Forums >> Glow Engines, Gas Engines, Fuel & Mfg Support Forums >> Engine Manufacturers Direct Support Forum >> Jett Engineering Support >> West 50 + QJ500 muffler?
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West 50 + QJ500 muffler? - 10/16/2005 5:54:09 AM   
Rudeboy



Posts: 3256
Joined: 12/9/2002
From: Bejing, BELGIUM
Status: offline 		Hi Bob,

I did a little experimenting this morning, and drilled out the muffler mounting holes in my West 50 to accommodate the bolts of a Jett Q500 muffler.
The engine responds pretty good to that muffler. It turned right up to 21K peak on an 8x8 APC sport prop (which I think is pretty nice performance) and a brand new P+L set (on 15% Wildcat heli fuel). The new piston and liner set is so tight it took me about 20 minutes to get it started, so performance may increase as the engine gets broken in... I've never seen/felt an engine so tight. It just locks up at anything below 1/3 throttle...
An ABC engine should be tight, but this one is rediculous

Now here's the question: should I prop the engine down a little more with the QJ muffler? Down into the 19's like with a Quikie Jett engine? How well does the muffler support "unloaded" rpm? It seemed to be at bit "over the top" on the 8x8... but since I have nothing to compare to in this matter, that's just an opinion...

I have been looking long and hard at one of those composite Q40 planes (I like the Polecat from Bruce DeChastel)... for a good looking sport fast plane, they are hard to beat IMO. And since pylon planes are generally VERY good flying planes... Basically, I need one...
Do you think the West/Jett combo will make a good powerplant in that application? Perhaps with a cut down/reshaped 8.8x9.0 or 8.8x9.25 prop?

PS: if you are interested, I will run a variety of stock APC Q500 props on this combo, and post the results here. Should make a nice comparison to the QJ500 engine and the Sport Jett and Super Sport engines.




Win, please post the results in the Glow Engines Forum where far more viewers will see them and benefit from your results, no-one except Bob would be permitted to post any comments to your test here and he posts over there also. Many Thanks.

< Message edited by hobbsy -- 10/16/2005 1:06:35 PM >

_____________________________

Revver Brother #33
...I think it needs more power...
       Post #: 1

RE: West 50 + QJ500 muffler? - 10/16/2005 2:47:47 PM   
bob27s



Posts: 4740
Joined: 4/9/2002
From: Cleveland, OH, USA
Status: offline 		Sounds like its running pretty well

Pipe/muffler tuning has a great deal to do with the way the engine will run.

With 8x8 at 21K, you are running flat on the pipe (as you noted) - thats close to the top end tuning number - what you would want to see in the air. Engine is not loaded.

The QJ500 muffler is tuned for running between 19K and about 21K rpm. On the Q-500 planes/engines we typically prop to run between 19,500 and 20,000 peak on the ground - with some props, as low as 19,000 - then set about 500-600 down. On the QJ-40, the props of choice are the APC 8.8x8.75, 8.8x9, 8.75x9W

On a SJ-50, for sport use with the QJ muffler.... your ground peak rpm should be between 18,500 and 19,800, and then back off - keeing the engine no lower than 18,000 for launch. Id recommend about the same for your West V1

So the 8x8 is too light. Its probably not loading the engine to the point where it is warming up enough - thus the tight piston/sleeve fit is not getting to the right size, and is real tight. (The west is a good engine - similar in construction to the Jett engines - and by inference, such would be the case).

Load the engine down with one of the Q-500 props, or a 9x7 or 9x8 or similar. Get it running closer to the range I noted above. If you find a prop you like that loads too much, clip the prop tips a bit until the rpm comes back up.

The 8.8x9.25 stock is a little heavy, the Q-500 engine can turn it on a good day, with a very carefully 'guessed at' needle - The SJ-50 tends to be able to turn it fairly well - but as you suggested, clipped a bit for speed applications works very well.... give that a try

Let me know how your testing and such goes.

Bob


_____________________________

Bob Brassell
Jett Engineering - Engine Mfg Support Forum Host

(in reply to Rudeboy)
       Post #: 2

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All Forums >> Glow Engines, Gas Engines, Fuel & Mfg Support Forums >> Engine Manufacturers Direct Support Forum >> Jett Engineering Support >> West 50 + QJ500 muffler?
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