JoeNoble

iTrader: (6)

when I had my last rx-7 somebody told me that you cant use a universal flow through muffler because rotaries have to have a certain amount of back pressure. Is this true?

mazdaverx713b

iTrader: (91)

sure, it just depends on how long you expect that el-cheapo muffler to last..a week, a month, a couple months at max...

and a quote from the 2nd gen FAQ:
"Can I use a Cherry Bomb/ Glass Pack Muffler?
The rotary engines exhaust temperature is very high, and often will melt the contents of cheaper mufflers that use fiberglass or glass packing. This (depending on quality) can happen in a month or two or in some cases in a few hours."

JoeNoble

iTrader: (6)

So what do the contents of a rotary muffler consist of? If I was to gut the cat would that help dissipate the heat?

JoeNoble

iTrader: (6)

yeah I used a cherry bomb on my last rx7 and it seamed to work fine though it was really loud cuz I had no converter.

Kentetsu

1. Rotaries do not require back pressure.
2. They require a muffler that can take the heat, which usually means stainless steel or ceramic filler.

jgrewe

iTrader: (1)

The motorsports mufflers have lava rock instead of fiberglass packing in them to give you an idea of what they have to deal with.

1979mazdarx7

is there any low-cost mufflers that can take the heat to last a while?

JoeNoble

iTrader: (6)

yeah what he said. is there? Im looking for something with some sound to it.

trochoid

iTrader: (6)

You either spend good money buying 1 muffler or nickel and dime buying many. Find a Borla on eBay.

Rx-7Doctor

iTrader: (13)

Just a small correction.

Gsl-SE models that want to still have the use of their 6 port actuators need to have back pressure in the exhaust to actuate the 6 port system.

1979mazdarx7

http://cgi.ebay.com/ebaymotors/Borla...spagenameZWDVW

how's that? its under $100 without shipping, and it appears to be somthing that doesnt make it sound like a ricer but does sound good.

rotornoob

iTrader: (2)

my el cheapo special canister went to crap about a week after i got it. that thing got so hot that the chrome and even the black body turned gold it registered 117 db with the silencer in.

Dr Rx

Do you have the link to the write up that allows owners to still run all ports off of the air pump. I ask this because i have an exhaust on my gsl-se and i don't know if the air pump conversion has been done or not.

Also i thought it was lack of exhaust velocity not backpressure that disabled the ports from opening.

orion84gsl

iTrader: (5)

https://www.rx7club.com/1st-generation-specific-1979-1985-18/borla-vs-backfire-backfire-wins-borla-shreaded-up-my-surprise-fg-778499/ Read through this and see what skimping on a muffler can do. Save some cash and buy an RB muffler. It'll save you some headaches later.

1979mazdarx7

so what is everyone running, other than stock?

1979mazdarx7

http://www.car-stuff.com/store/?N=11...667+11920+9164

how are these?

trochoid

iTrader: (6)

In a 2-1/4 or 2-1/2" inlet/outlet, not a 3"

lx_machado

iTrader: (13)

magnaflow, but im not liking it too much.

FirebirdSlayer666

iTrader: (3)

Single RB power pulse muffler. I love it, it's nice and quiet thru town and then screams when the secondaries open up. Also, a properly built exhaust will yield better power and torque than no back pressure or open header. I ran open header for about 3 weeks. It was too painfull to take above 4000RPMs and it went nowhere in a hurry

tallbozo

iTrader: (5)

magnaflow polished stainless. Im currently running it without cats so its pretty loud when you get on it, but its deep down low. 3 years and no issues!

Jaime Enriquez

http://racingbeat.com/FRmazda1.htm

scroll to the "hi-performance exhaust systems", go down to the SE Streetport system....nuff said.

Spyride

mmm, open header = head ache at any rpm

trochoid

iTrader: (6)

Sam wasn't skimping when he bought that muffler, even though when I bought the pair of them they were at a good price. I still have the mate to it that will eventually go on the REPU. This is the first Borla I've seen explode like that but not the first muffler on a rotary that has done that. I've seen pics of both oem and Racing Beat mufflers that have exploded due to too much vapor build up which is what I suspect happened to Sam's. Since Borla is sending Sam near what I paid for both mufflers together, I'd say he came out quite well.