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Engine Muffler extensions????

Old 09-07-2008, 08:12 AM
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Aerobat5
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Default Engine Muffler extensions????

I have a 4*60, and with the high mount muffler from an OS .61 engine, its' a mess after each flight. I want to extend the exhaust down to the bottom of the fuselage to keep the oil clear of the plane. How long can you make an extension without messing up the compression on a 2 stroke engine???????????
Old 09-07-2008, 02:26 PM
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ceecrb1
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Default RE: Engine Muffler extensions????

I tried this and it caused many dead-sticks.

I resorted to 2euro spray bottle with water and washing up liquid.. and a peice of old cut up Tshirt.
Funnily enough it works better as an extender will only reduce the mess made, you will always at some point "turn" the plane in such a way that it will splatter itself, meaning you still have to clean it!
Old 09-07-2008, 05:02 PM
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Gringo Flyer
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Default RE: Engine Muffler extensions????

I dont think you will be able to run the exhaust out the bottom without effecting engine performance. You can use a standard exhaust deflector. They dont solve the problem but do help.

I really like 4 strokes for that reason, a lot less mess.
Old 09-07-2008, 09:41 PM
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Campy
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Default RE: Engine Muffler extensions????

FWIW - I have used 3 exhaust extensions on a 46 2 stroke. I opened up the inside of one of the extensions with a dremel and had to fabricate some new bolts. I had a little drop in power, but nothing major - I lost about 600 rpms.

If you decide to go this route, check the opening in the extension against the exhaust port opening on the engine. I found the DuBro extensions had the same exhaust opening size as my engine, HOWEVER, the opening in the OS extension was almost 3/16" SMALLER in width than the exhaust port opening on the engine. I opened this up using a dremel and a file.

For the bolts get some 3mm all threaded rod. Screw the rod through the extensions and into the engine and mark how long you need it. Cut the rod and double nut it. THEN SOLDER THE DOUBLE NUTS TO THE THREADED ROD. Use a cutoff wheel in a dremel and cut a slot in the top nut. You only want to go about 3/4 of the way through the nut so as to keep the strength.
Old 09-07-2008, 10:18 PM
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Default RE: Engine Muffler extensions????

Some engines no problems, other engines you can get A problem?? I have even found engines that didn't run well with the deflectors. Try it and see what happens.
Old 09-08-2008, 03:28 AM
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Default RE: Engine Muffler extensions????

I have run a length of silicon pipe from the end of the muffler to the bottom of the aircraft, no problem. I's say it was about 6" in length.
If you're having problems, just remove the internal baffel from inside the muffler so it isn't so restrictive.
A buddy of mine ran made a beautiful curved length of alloy pipe that was say at least 10" from a .40 on a scale model. He didn't have problems. In fact He insisted the engine performed better!
There is no rocket science here, it's a hobbly Aerobat55. Just strap something on and see how it goes.
Old 09-08-2008, 08:43 AM
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da Rock
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Default RE: Engine Muffler extensions????

How long?

Good thing about out hobby, is lots of things are very easy to test to find the best answer.

The Ultimate has silicone extensions that started out longer. I cut back until the bottom of the airplane showed oil residue. Then I simply slid them back out longer to the last good length. Not very long on that model, right. The airplane decides the length for you.

If you look into the shadow of the P47 you'll see a blue silicone extension that's off the end of a stock OS Max muffler. I ran the muffler back through the firewall and the front part of the fuselage and through the belly under the wing. Yeah, some people will do anything to save the price of a replacement part when the paid for one will work. That extension needs to be that long where it is. The engine doesn't seem to mind.
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Old 09-08-2008, 10:10 PM
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freeflight101
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Default RE: Engine Muffler extensions????

i have a sig kadet sr with a magnum .46 macs pipe and 12 inch extension and there doesnt seem to be and problems. i did open up the end of the macs pipe a little though and port matched it to the motor, 12 flights since the mod an no problems at all... and sounds cool too
Old 09-09-2008, 02:39 AM
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sebo
 
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Default RE: Engine Muffler extensions????

What kind of material are you using for an extension?
Old 09-09-2008, 06:45 AM
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airbusdrvr
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Default RE: Engine Muffler extensions????

I didn't have time to search and find the blue stuff, but you could use this type tubing for an extension. Get one that has the inside diameter the same as the OD on the exhaust pipe of your muffler. http://www3.towerhobbies.com/cgi-bin...?&I=LXMMN0&P=7
Old 09-09-2008, 08:51 AM
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Default RE: Engine Muffler extensions????

Thanks. It's so easy when you know exactly what you are looking for.
I really appreciate your help.
SEBO

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