custom-vince Posted October 25, 2012 Share Posted October 25, 2012 im still looking at ways to reduce engine noise. wrapping expansion chamber, extending muffler... The TOP80 and Nirvana Exhaust that gets fitted to their Simonini. Neither of which resemble the scooter style expansion chamber, and tubular muffler that is common. BUT both of those engine sound sweeter (lower tone) and their exhaust systems are lighter weight. How does it work without the tuned shape of an expansion chamber to give the correct back pressure? What is in them? any silencer wadding, divider baffles Why is that style not used on other machines? polini, vitorazzi, h&e, cisco, corsair, sky-engines, fly engines, technofly, simonini, etc top80 exhaust Nirvana Simonini I was never fully into scooters or 2 stroke bikes. I had an RG500 but that has 4 tiny pipes and made a huge load of noise which was fun at the time. Quote Link to comment Share on other sites More sharing options...
skybound Posted October 25, 2012 Share Posted October 25, 2012 Because the tuning shape is inside masked by the outside. Quote Link to comment Share on other sites More sharing options...
custom-vince Posted October 25, 2012 Author Share Posted October 25, 2012 Is that it, it still has and needs the cone shape to reverberate the pulse wave back towards the combustion chamber to crest the nessersary back pressure. A simple square ended tube can't do that? I read adding 5" to the muffler can reduce noise by a further 5db Wrapping the expansion chamber again reduces noise. Quote Link to comment Share on other sites More sharing options...
bigpapa Posted October 26, 2012 Share Posted October 26, 2012 I guess the shape of the cone reflects the range of the 'powerband'. The cone reflects the pressure wave progressively so the pulse returns to the exhaust port at the correct time to keep the fuel mix in the head. A shallow cone would give a wider but weaker powerband. A steep/flat cone would give a very good return pulse, but because it is so narrow it will only work for a small rpm range. Quote Link to comment Share on other sites More sharing options...
skybound Posted October 29, 2012 Share Posted October 29, 2012 Is that it, it still has and needs the cone shape to reverberate the pulse wave back towards the combustion chamber to crest the nessersary back pressure. A simple square ended tube can't do that?I read adding 5" to the muffler can reduce noise by a further 5db Wrapping the expansion chamber again reduces noise. Vince, There are cones inside just not in the conventional way. If you cut one open you will understand. Quote Link to comment Share on other sites More sharing options...
custom-vince Posted November 11, 2012 Author Share Posted November 11, 2012 Ok. That makes sense. I'm currently now looking at a prop with flip tips to reduce noise. Interested how much quieter I can make a paramotor. Quote Link to comment Share on other sites More sharing options...
craigthompson Posted January 18, 2013 Share Posted January 18, 2013 Ok. That makes sense. I'm currently now looking at a prop with flip tips to reduce noise. Interested how much quieter I can make a paramotor. I pinched this link from an unanswered post. It may help: http://www.thedbsnorkel.com/ Quote Link to comment Share on other sites More sharing options...
pete_b Posted January 18, 2013 Share Posted January 18, 2013 Ok. That makes sense. I'm currently now looking at a prop with flip tips to reduce noise. Interested how much quieter I can make a paramotor. Not a lot tried them. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.