mikeb

changing the exhaust shouldn't cause any problems. I know I'm gonna change mine. I'm in ca and I do have to worry but mainly just about cops if my exhaust is too loud.

dcfc3s

First off, there are a few components to the exhaust. There's the catalytic converter, or cat, that's closest to the engine. Then, there's the "cat-back" section, which is literally from the cat back to the tailpipe.

Legally, you can change out the cat-back section of the exhaust. By law, you can't do anything with the cat, but in many states it's kind of a grey area - it's illegal, but so is taping movies off HBO. No one really checks up on it.

There's also the exhaust manifold - this is a cast iron hunk bolted right to the engine, and the cat is bolted to it.

When designing the exhaust system, Mazda (as most car manufacturers do) had a number of objectives -

- It had to be quiet.
- It had to not rust out before the warranty expires
- It had to be relatively inexpensive
- It has to pass VERY strict federal emissions standards
- It has to be easy to install on the assembly line

ALL THOSE factors are looked at BEFORE performance.

With that said, Mazda has traditionally made VERY restrictive mufflers on the RX-7's. Rotaries are VERY loud, and as I'm sure you know your car is VERY quiet. The only way to accomplish this is with a massive, restrictive muffler.

The cat does quite a bit of sound muffling as well. Even if you had no cat-back on the car at all or just straight pipe, the car wouldn't be THAT loud. It would be loud, though .

Aftermarket exhausts typically are better built and of higher quality components than stock, and one of their first objectives is making more power. They will be louder than stock, but with just a cat-back, a good exhaust will have a nice, deep, sporty sound, but not loud and obnoxious.

Aftermarket parts to replace the cat are typically called midpipes or straight pipes. Again, grey area, and you can't pass an emissions test with one, but power can be gained there.

The stock exhaust manifold is replaced with headers, which typically is a tubular manifold that keeps the exhaust pulses separate for more power. Many headers are legal - they bolt to the engine, and the cat bolts to the headers.

Right now, there isn't much out there exhaust-wise. In a year, you're gonna see TONS of options - rotary powered vehicles have always attracted enthusiasts, and enthusiasts like modifying cars.

Changing the exhaust should not lead to any reliability problems - just more power and a better sound.

Dale

mikeb

why doesn't anyone want everyone to hear them coming

david borla

Yes, there are aftermarket exhausts that do not increase the decible level of your exhaust. However, the tonal quality will be different than stock.

In our case, the Borla exhaust for the RX8 has a deeper, throatier exhaust note than stock without it being louder. There is no resonance inside of the cabin, we worked very hard on this.

wakeech

in a word, yes. a traditional muffler absorbs the pressure waves of the gasses coming out of the tailpipe, to eliminate the pressure waves which would then come out of the tail pipe and hit our ears as sound. you can't remove energy from the exhaust without hindering its egress from the engine.

there are other muffling techniques, like resonators, or high-tech mic-and-speaker theoretical systems (like an electronic dynamic resonator) which would just modulate the pressure in the tail pipe in complement to the pressure waves in the exhaust to neutralize any fluctuation, but resonating baffle units aren't necessarily more effective at reducing sound or allowing exhaust to flow unimpeded, and the high-tech solution is as rediculous as it sounds.

edit: actually, not quite. if you have two systems (one a straight through, perforated core muffler and the other a contorted dual-outlet glass pack) which have the ability to reduce noise emissions equally, one exhaust path will inherently have less back pressure than the other. if though, you're comparing two identical exhaust paths, with one absorbing more sound than the other, the louder one will be more effective.

also, the tone of the exhaust note can be changed with the size of the tip you put on the end, not to mention the volume of the resonating chamber and other thingies too...

RotorMotor

Because it's annoying as hell and I respect my neighbors....

mikeb

are you serious

RotorMotor

Naw, just joshin ya bro...

Of course I'm serious. I hate those punks that wind out their cars with that annoying rice sound down residential streets at 2AM (a la one ricer at the end of my street), let alone over-blown bass that people install for everybody else's "enjoyment".

Besides flossin' with your car is for people who have nothing else to offer the world. Don't get me wrong, I'm proud of my car, but, no I don't need half the city hearing me coming a mile away....

mikeb

I already have the bass (2 12 inch subs) in my 8 and I can't wait to get a mazdaspeed or greddy exhaust. When I do maybe we can meet or I'll see you in San Diego buddy, so you can check it out

rxtreme

iTrader: (1)

What about the twinloop design used by Mugen? I've heard good things about that design (good power gains with a good sound--not too loud). I'm not even quite sure how it works. Maybe Wakeech or Mr. Borla can elaborate.

Also, Mr. Borla, if you could elaborate on your exhaust system for the RX-8 a little more that would be great.

panda

im guna remove my cats(just 1) tomorrow, just to see what it sounds like :-)



andrew

RX22

I agree!!!

Section 8

Tell me if there are 1, 2 or 3 cats then, I think I'm leading the masses astray..I can't find any supporting evidence of my previous statement. Maybe I was drunk or something at the time...

Efini 8

I will be bringing my car into the shop for custom exhaust. Only problem is the small outlet that cannot fit canisters rather just smaller tips. also I will be dynoing the performance gains also. hopefully getting a titanium system. BTW: This is all gunna be legal, so no $1000 fines for me

mikeb

post info and pics- who is doing your work on the 8

david borla

Will it be a cat-back? How much will it cost for just the materials (titanium)? What do you anticipate the weight savings of titanium will be over stainless? What will the labor costs be? Who is doing the labor? Will they be welding with titanium? Will the flanges be titanium? Whose mufflers will you be buying? Will they be titanium as well? How long will your vehicle be out of commision?

This is a very exciting project. Please keep us posted.

djmano

since im all about attention grabbing (duh, i drive an rx8!) , i want to know what kinda flames people are spitting with their aftermarket exhausts. ive heard the borla can yield some good ones at high rpms, but what about any of the other aftermarket exhausts? any pics, vid clips, etc?

i was hanging out with a friend of mine who happens to own a FD....he was making me have flame throwing envy :o

KC_RX-8

djmano, just be prepared to be "flamed". Not by me, but all of those "rice-haters" in the world.

zoom44

just get a plug and tap it into you exhaust. run power to it with a switch in your dash. whenever you want to shoot flames flick the switch. in some cars you would have to enrich the AF ratio but in this car you won't have to.

bureau13

If the guy had a catless FD it doesn't need any "cheating" with plugs in the exhaust. Now, my FD still has its cat, and I've never seen it shoot flames. I'm surprised the RX-8 is doing that with just a cat-back...

jds

zoom44

who's cheating? he wants to shoot flames i gave him the quickest and cheapest way to do it. learned it from my dad and uncles who used to do it to hot rods in the 1950's and i'm sure it was done before that.

red_rx8_red_int

I agree. Not rice. A nice effect. At the perils of being accused of rice myself. My teenager is really pressing me to put red neon undercarriage lights on, and I'm seriously considering it. I think it would make the car look more sweet/badass at night. Tonight we saw two cars with them, one with blue lighting and one with green, they both looked great.

On a related note, I've had comments that the car is Sweet and "what a badass car". Badass a little more than sweet. Is the 8:

Sweet;

Badass; or

Sweet and Badass.

I think it's both at once!

Dugless

What the hell, flames???!!!!!

This is my first rotary, do they spit fire?????

djmano

there is something about the rotarys engine that naturally lets it spit flames. im not really sure what the mecahnics are behind it, maybe someone else on the board can give us a good explanation.

btw.....although attention grabbing gimmicks are usually known as rice i believe that natural bursts of flame out of the tailpipes is not only one of the coolest things you can see, but one of the most indimidating.

deadrx7conv

Catalytics do everything possible to prevent flames. They take care of all that unburned fuel. As long as they are working, you won't get decent flames(if any at all).

Get rid of the cat and you'll have flames with almost any exhaust. That means you'll need a SESeliminator(02 tricker).