Megaphones

[Gaanja]

Can someone please tell me how megaphones work in a exhaust system??

[Gaanja]

Can someone please tell me how megaphones work in a exhaust system??

[exFSAE]

Have you tried emailing Burns Stainless?

[Gaanja]

yes i did. I did not get a reply

[samphlett]

Maybe they don't know. Just accumulated years of trial and error?

[Gaanja]

Hmm... not commenting about that.. But if someone knows the logic could you please tell me??

[Damon Pipenberg]

A megaphone is a type of acoustic horn, so if you find a book on acoustics you can learn how it works. Basically the horn optimizes the transfer of sound waves from in the exhaust pipe to free air. This will make the exhaust sound louder and more directional.

[frenzy]

don't they work like a diffusor?
i've seen pipes like that on an old porsche 914 and the owner said, he measured a small increase in bhp in comparison to straight pipes..

[PatClarke]

Frenzy,
back in the days when noise wasn't an issue, megaphone exhausts were commonplace. When 500cc singles ruled the world of motorcycle racing, megaphones or 'Meggas' were universally used. Google a picture of a Manx Norton and you will see what I mean.

They worked with exhaust extraction at specific RPMs and so led to expressions like 'On the megga' or 'On the pipe' when the harmonics tuned in.

Most of the guys who raced with this kind of exhaust are deaf as posts these days. I suspect it would be extremely difficult to get a megaphone exhaust past the noise test at FSAE.

Cheers
Pat

[TorqueWrench]

UB had a megaphone into a muffler design last year on our V-Twin. It got past sound, but just barely...

The idea behind it was to increase the tuning effect at a specific RPM more than simply a tuned pipe could achieve. While this may not be seen as much of a benefit to a sequential transmission because you pass very quickly over this point, a CVT can actually make good use of it by setting the holding RPM of the clutches to the megaphone's tuned RPM.

[Wesley]

One of UTA's cars has a converging/diverging "megaphone" that I would imagine acts in a similar manner. It's also pretty loud.