nickduncs84 Posted November 25, 2015 Share Posted November 25, 2015 Backstory is that I recently had a crack in one of the two resonators of my io390 exhaust system. The builder had an auto resonator on one side and what looked to be a more light weight aviation specific muffler on the other which was old and is what failed. I just read the article in kitplanes which mentions the issue of back pressure created by mufflers. So my question is, are automotive resonators ok to use or are their potential issues?? 1 Link to comment Share on other sites More sharing options...
bexrbetter Posted November 25, 2015 Share Posted November 25, 2015 Mate at 2800 rpm or so it's not really a big issue which type of muffler you use and do you want a noisy, tiring trip for the sake of maybe 1 hp? You can gain a bit though with a decent, tuned length extractor system, but only if you need to replace your whole exhaust as the cost won't be paid back in fuel savings for a long time. Look up Power Flow Systems in America who's prices are insane and if you like the idea give me a yell and I'll find you someone local prob at 1/4 the price. http://www.powerflowsystems.com/index.php 1 Link to comment Share on other sites More sharing options...
facthunter Posted November 26, 2015 Share Posted November 26, 2015 Some baffles have been known to part burn out and move and restrict flow causing loss of power and overheating. Other issues are CO poisoning with the cabin heater muffs getting exhaust leaks. Light weight non cracking and good fit are the things you want and the whole thing should hang off the engine, unless you use a flexible section. Nev. 1 Link to comment Share on other sites More sharing options...
nickduncs84 Posted November 26, 2015 Author Share Posted November 26, 2015 Excellent thanks bex that's the answer I was after. Not worried about losing a couple of hp. It was more the comments about the other side affects of back pressure that was worrying. I think the exhaust system is a powerflo one. And as for price, yes I agree and it's the reason why I went for experimental category vs say a Maule. Quote for the muffler from an aviation company was over $1000. Paid $40 from a local exhaust store. 1 Link to comment Share on other sites More sharing options...
nickduncs84 Posted November 26, 2015 Author Share Posted November 26, 2015 Some baffles have been known to part burn out and move and restrict flow causing loss of power and overheating. Other issues are CO poisoning with the cabin heater muffs getting exhaust leaks. Light weight non cracking and good fit are the things you want and the whole thing should hang off the engine, unless you use a flexible section. Nev. Yes there were a few issues that came up during all of this. There was a hole in the cabin heat cuff which was no good. Given what I'm using this plane for, I don't need heat and so just removed that completely. The weight of the resonators is also a factor and as such we installed a couple of braces to support the weight. It's not the ideal setup I'm sure. The weight of the resonators alone is probably a good 7 or 8kg. But it's a lot cheaper than the alternative and seems to do the job.... Link to comment Share on other sites More sharing options...
facthunter Posted November 26, 2015 Share Posted November 26, 2015 With a flat six you can have one each side. I don't like back pressure. There's advantages in sticking with original if it's a common system for that engine. Just order the part and fit wherever you are. No guesswork. Nev Link to comment Share on other sites More sharing options...
nickduncs84 Posted November 26, 2015 Author Share Posted November 26, 2015 yeah that was part of the problem. it's an io-390 with what I believe is a powerflo exhaust system but no one could find the part and there was already a resonator on the other side. It was going to be expensive and a long wait to sort out so whacked a resonator on and it doesn't seem to have effected anything.....the builder was an auto mechanic and had been running it with a resonator, so i assume he didn't think it was an issue. A bit hard to get definitive answers as to whether it's ok or not. All I know is it seems to be working fine. no abnormal readings since install... ?? but what would I know Link to comment Share on other sites More sharing options...
jakej Posted November 26, 2015 Share Posted November 26, 2015 Nick Can you call me please ? Link to comment Share on other sites More sharing options...
nickduncs84 Posted November 26, 2015 Author Share Posted November 26, 2015 I just wanted to clarify for the avoidance of doubt that I am not the builder and that the work was done by a licensed LAME in accordance with the rules! The LAME was the one that tracked down the exhaust parts but in the end derided the resonator was the best option. Link to comment Share on other sites More sharing options...
bexrbetter Posted November 26, 2015 Share Posted November 26, 2015 NickCan you call me please ? What did you want him to call you? Nick because the 390 is injected, it may pay to contact Ross Farnham (member here as rv6ejguy) just to check that side of it won't be effected. Very clever and helpful guy, and very approachable. http://sdsefi.com/ Link to comment Share on other sites More sharing options...
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