NA FC Exhausts
 

Hoping someone can help me here.
I know it's a common topic, but so far in my searching I haven't found out what baffle material people use. A friend of mine is thinking of making his own exhaust, and can get the stainless parts for the mufflers, just not the baffles to deal with the heat.
Fibreglass and rotaries is just a no go we've found as the high heat melts the material. Anyone have any suggestions, or know what materials people use for rotary exhausts?

Many thanks

Mike

Stainless or aluminized steel pipe is fine. Magnaflow makes good mufflers packed with stainless. I would recommend running a single pipe to the rear with a Magnaflow muffler as a resonator and a "turbo style" muffler under the rear bumper.

I want to try and build a muffler with lava rocks normally used in gas grills.

pretty sure they use ceramic and stainless steel for packing.

I wonder how well that would work?

there are no stupid questions or answers, just stupid people.

It would probably rattle like crazy.

Also, considering the rocks not fitting tightly around each other, and the fact they will also not fit tightly around the baffled inner tube, it would probably flow worse than a blown out louvered glass pack.

Yeah, remove from head, install in muffler!

2 problems solved!:icon_tup:

LOL, you guys are brutal.
Now I'm definitely going to try it. :P

If you do it, there better be some damn video. :)

I'll do my best. ;)
Keep in mind, I might be looking for a different result than some of you. My car only has to be under the SCCA noise limit for autocross... Don't recall what that is right now, 100db @ 50 ft or something like that.
So if it rattles... don't really care. I doubt I'd hear it over all the other racket.

Pretty sure it's 93dB @50'. directly behind the car at a point on course where the car should be WOT. Which an inadequately muffled na rotary can easily blow past (we had a bridgeported one that was over 120dB show up a few years back - course workers would turn their backs and cover their ears until it was 200' away. Shocking loud.)

i just have the cat removed and replaced with a piece of generic steel exhaust pipe, kept the OEM mufflers. its a nicer sound without being overly harsh or loud.

So you're going for the exact same goal as me.

Yes, 100dB at 50' with the meter on slow.

You mean like the stupid people who don't know that many Mazda GT race cars use a Mazda Comp muffler that is packed with lava rock because it is more durable than stainless steel packing? ;)

and done...

http://www.youtube.com/watch?v=LEsLktGzNx8

Think the steel wool was going to be the route to take, but after seeing that vid.......
Has anyone on here used it as a silencer material?

Considering straight through designs don't really absorb much noise, hell you might as well run a 2.25 inch straight pipe. This is what I am going to do, and ditch these glass packs I have.

Straight through mufflers do a lot - it's just that their sound attenuation at high frequencies is good but the low frequency attenuation is not good.

A quality stainless-steel packed muffler after the cats works great to kill the high frequency rasp that NA rotaries have. A turbo-style muffler (these tend to be a few perforated tubes that the exhaust gases pass through radially) in the rear does a great job at attenuating the low frequencies.