Silicon exhaust extensions
12-16-2002, 09:08 AM
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Silicon exhaust extensions
Silicon exhaust extensions/deflector really drops the sound level. I have tried this on a fox engine with good results and I think this is because of the flexibility in the tube.
12-16-2002, 10:55 AM
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By at least 2db. We have a 90db limit at our field. I was at 93db one day when the noise police pegged me. I put one of those on, brought it down to 91db and changed an 11 x 6 apc to a 12 x 5 top flight and was running at 88db. When every one had their backs turned I sneaked the 11 x 6 back on.
Happy Fly'n....
Happy Fly'n....
12-16-2002, 06:48 PM
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Silicon exhaust extensions
Do these extensions change the way your engine runs?
Do they change the setup because of added back pressure?Do you need to adjust the needle settings?
Bill
Do they change the setup because of added back pressure?Do you need to adjust the needle settings?
Bill
12-16-2002, 09:56 PM
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Silicon exhaust extensions
These extensions should not be more than 3" long or you will have problem idling. You don't want to have too much back-pressure in the muffler on the 2-strokers. Especially, on OS and Magnum, when you use an extension, remove the baffle plate inside the muffler. I fly without the baffle plate either with or without the extension. It will be a little noisier, but you can really see the increase in performance.
12-17-2002, 06:32 AM
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I don't agree that the increased lenght will effect the back pressure much. If you use the correct size extension... I mean for 40 size engine use the recommended 40 size extension and with 60 use the 60 size extension. The correct internal diameter will not effect the back pressure and if the extension is longer it will reduce the noise level much than you can expect.
12-17-2002, 05:35 PM
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2-strokers don't have exhaust valve like 4-strokers to prevent back-pressure from creating a drag on the piston. I have tested using a 7" extension on my OS46FX: noise is low but I couldn't get idle to hold. I removed the 7" extension on put on the Dubro 3", it works great. Off the shelf extensions either for .40 or .60, they are around 3" - 3.25". You should check the rpm with and without the extension (or any extension) I'll bet you will see a drop with the extension.
