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Engine basics => Engine set up tips => Topic started by: DanielGelinas on August 24, 2011, 12:17:26 PM
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Hello all!
Do any of you run tongue mufflers on the OS LA series or do you just run the stock muffler with or without muffler pressure?
I have .25, .40 and .46 engines I would like to run with tongue muffles, if I can, just to save a little nose weight.
If so, what a your setups with the tongue mufflers?
Thanks for your recommendations! H^^
-Danny
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I have used the Randy Smith CNC tube muffler with muffler pressure and like the sound a lot. A bit heavier than a tongue muffler, but nowhere near as heavy as the stocker. I drilled & tapped a hole for a DuBro pressure tap, 6-32, I think. You need to put it on the area that's double wall thickness, and that's not all that easy to determine, because the fit & finish is so nice. They sound good, but need a "rubber ducky" to blow some of the exhaust away from the model.
Tongue mufflers have a fairly harsh bark on 'em. A quieter muffler actually lets you relax and fly better, because it just sounds slower. Funny how the brain works. H^^ Steve
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I have tried tounge mufflers on the LA engines, never was totally happy with them. Especially on the 46. Not sure why since I am not really an engine guy. I too use the Randy Smith CNC tube muffler, its only about a 1/2 ounce heavier than a tongue muffler and while delivering a pleasant tone, it also delivers good performance. Personally I am not a fan of tongue mufflers, even if you need to balance out the extra half ounce for the RS tube, it only takes a 1/4 ounce or so in the tail to accomplish this .
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Thanks fo the reply.
So I assume moste people run with the stock muffler with or without muffler pressure OR a pipe?
Thanks,
-Danny
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Few run tuned pipes on the LA series of engines. Some run the stock muffler but it is heavy and not real attractive. Most prefer after market tube mufflers. Is your airplane nose heavy?, if not don't worry about the few extra grams of weight a tube muffler will add. Tongue mufflers can work but I have found that the LA-46 in particular runs better on a tube muffler. Muffler pressure or not?...I prefer "not" but some engines run better with it. Try it both ways and then decide. My current LA-46 set-up is a Randy Smith tube muffler on muffler pressure. 8)
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If noise isn't a particular concern, then tongue mufflers are OK. The main idea is to get exhaust goo out and away from the fuselage. So why don't they make tongue mufflers long enough to accomplish that? I quit using them only because they are useless in directing exhaust away. I'm much happier with my RE engines, where I can add an extension to exit about 2" below the fuselage bottom.
Floyd
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I have an LA 46 and have used a tongue muffler. My observation is that the tongue muffler may be too restrictive and cause the engine to run hotter.
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If noise isn't a particular concern, then tongue mufflers are OK. The main idea is to get exhaust goo out and away from the fuselage. So why don't they make tongue mufflers long enough to accomplish that? I quit using them only because they are useless in directing exhaust away. I'm much happier with my RE engines, where I can add an extension to exit about 2" below the fuselage bottom.
Floyd
The guiding reason behind the use of a minimalistic and short tongue muffler is weight. The less of the better but .............. they can indeed be made quieter with a longer body and this in turn gets the "goo out and away from the fuselage. "
But I too hate the design unless it approaches at least 6 times the swept volume of the engine - this enlarged volume allows the hot exhaust gases enough room to expand and cool thereby getting the heat away from the engine.
Rear exhaust has to be the ultimate, I agree!
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Is this what your looking for?
http://shop.dubro.com/products/productdetail/6%22+Exhaust+Extension+Stock+%28QTY/PKG%3A+1+%29/part_number=213/101.0.1.1.5161.5189.0.0.0?pp=12&
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The dubro extension is what i use to make most of my OS tongue mufflers. I can make 2 or 3 , depending on length i need from one $6 extension. Very easy to do by drilling a hole through each side to fit and make an aluminum end cap. Use 2 1/2 or 3 inch bolts with locknuts. As they come the width fits the la 46. I also cut them in half to remove a little metal and JB weld back together to fit the la 25. Tap for a pressure fitting if needed.
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I have an LA 46 and have used a tongue muffler. My observation is that the tongue muffler may be too restrictive and cause the engine to run hotter.
Just curious how many holes do you have on these tongue muffler? and what size holes? It does makes quite a bit of difference.
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There is a new MACs controline muffler for the 46LA and others. Claims to weigh less tha 1.5 ounces.
ttp://www.macspro.com/onepiece.asp#CL
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Thanks Guys,
I'm no engine expert. THe main reason behind the tongue muffler for me in improved engine performance and weight.
I have ordered a tongue muffler from RSM and I'll give it a try. From what I have read so far, they should give better performance than the stock muffler.
I'll try it as is and if need be I may put a few extra holes in it.
Thanks,
-d H^^
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Randy has some really nice tongue mufflers. Matter of fact, they are the favorites out at our field. You
won't go wrong with his products and he is down right amazing in his engine knowledge!
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Hi Daniel,
I hate tongue mufflers because they simply don't muffle. I think they are an apology for getting around the silencer rule! A thin wall tube muffler is by far and away the better solution. A good one approaches the weight of a tongue muffler and they have a much more mellow tone and did I say that they do muffle!
Regards,
Andrew.
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IMHO....what Steve Helmick said !
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I find the tongue muffler are not too bad if you're running it at around 8000rpm (4-4 style run). anywhere near 9000rpm or higher, and it gets pretty loud. H^^
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There is a new MACs controline muffler for the 46LA and others. Claims to weigh less tha 1.5 ounces.
ttp://www.macspro.com/onepiece.asp#CL
http://www.macspro.com/onepiece.asp#CL (http://www.macspro.com/onepiece.asp#CL)
The MACS Mufflers are not a bad way to go. I have run them, as has Scott Riese. They do not always fit well with upright or inverted engine installs (tend to interfere with the wing) and often don't fit well on profiles with side mount engines (tending to interfere with the LG legs, unless wing gear or trike).
They also need to hit their tuned rpm, which is probably still 10,200 rpm for the .40/.46. The 11.5 x 4 APC works well for this setup on the .46LA. I would try the 12.25 x 3.75 APC or 12-4 APC on an R/C ST G.51 or Magnum/APC . 46, .53 or .52. The bigger engines may have a lower rpm tuning, but I would call Mac and ask him. Do NOT add a rubber ducky to one of these. They are a 1/4 wave tuned pipe. If they are at the right rpm, they will sound rather like the wheels are going to fall off. H^^ Steve
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Can those of you using tongue mufflers with the LA 46 tell me how many holes and what diameter?
I have tongues from Randy and Big Art and the total outlet areas of the two are very different.