Dyno with two mufflers?

[Scooter]

Has anyone dyno'ed their RX-7 with the TWO mufflers installed that are necessary to meet a 92db sound limit?

Cuz I just did. Let's compare.

[VinnyV81]

I wasn't aware that two mufflers were required? It would be interesting to know what a stock 6 port motor will dyno though...

[lateapex911]

I don't think he's saying that they are required by rules, I think he's saying that he tried two less restrictive mufflers in an attempt to get under sound regs rather than one more restrictive, (but quieter) muffler.

The cost vs benefit ratio is weight vs hp.

So, what are the conclusions?

[racingralph]

the 2 mufflers isn't just to be quieter.the 1st one, after the header,is really an explansion chamber (kinda like a 2 cycle). the 2nd muffler tones the sound down.the right combo....makes more horse power. contact mike at isc , the guys at speed source or steve e. these guys can build/sell this exhaust systems. hope this helps. ralph

[mustanghammer]

I'd check with Mazdatrix. I have seen their EP RX7's at the Runoffs with two mufflers so that they could meet sound at their home tracks. They were fast with and without the extra mufflers

www.mazdatrix.com

[Scooter]

So I have a full-dual exhaust that runs two pipes all the way out with two mufflers, one at each end. (And an expansion chamber in the middle of each pipe.)

It's quiet enough to be under 92db at the track. (The quietest limit so far around here.) Plus, since the mufflers are at the ends and they only service one rotor apiece, they don't seem to die.

A lot of people run a single, 3" pipe setup with a muffler in the middle instead of an expansion chamber, and with another muffler at the end. These systems seem to be quite enough for 92db, I think, but they also eat mufflers from heat.

If you don't run a second muffler in the middle of the exhaust, you will probably run about 98-100 db from what I understand. But I would love to hear from someone who dyno'ed a single pipe exhaust with both mufflers in place. A single-muffler exhaust making 100db does me NO good since I can't race like that at my home tracks.