reducing drone

Nikon FM · 11-27-2009, 10:50 PM

Quote:

Originally Posted by Modshack

I think it's a litte more complex than that... Typically those chambers are called Helmholtz resonators. They are used to dampen resonances
but usually used in intakes. There is one on the Z in the drivers side intake accordion. You'll see them on many cars in various shapes, tuned to cancel out natural frequencies. I think it would take some smart acoustical engineer to come up with something for the exhaust that would work on your system..

Ark Performance - Type 2 Stainless Steel True-Dual Exhaust

"Here's my 2 cents:

Essentially the second set of pipes are Helmholtz resonators, this is purely acoustic in nature and not necessarily performance related. The performance related aspects of this system can be attributed to the less restrictive flow path compared to the OEM system (including the x-pipe). The design "engineers" need to speak up to a level of explanation that does not give away their tricks.

I like this system, I think I'll purchase it but will not move until we see comparative dynos."

The side branches most likely are targeting a limited RPM range where flow conditions set up the "drone". The ~2k rpm condition (where drone occurs) is probably the targeted design point for the resonators. Higher RPMs mean a different flow so this becomes an off condition for the resonator design and the side pipes are there for looks.....but I kind of like them anyway

Done with the book...