Author Topic: Lets talk about exhausts...  (Read 1352 times)

0 Members and 1 Guest are viewing this topic.

Offline fidelity101

  • Sr. Member
  • ****
  • Posts: 462
  • Karma: 4
Lets talk about exhausts...
« on: February 06, 2012, 02:02:33 PM »
The FC is more of a race car than a road car anyways and the more modular it is the better, ease of service is key.

The twin exhaust looks good and sounds good, aside from it never sitting square in the bumper cut outs...

So I'm thinking of going to a single exhaust so I can deal with it easier but with this engine setup I through a cat-back on (when I still used a RB pre-silencer) and put on my friends ebay 3" to fart can SSautochrome exhaust and it was WAAAAAAY to loud. I put videos up on my youtube,

You are not allowed to view links. Register or Login

(for reference)

but now I;m thinking of sticking with my 2.5" header back to a muffler with 3" outlet.
I'm thinking a borla possibly either oval or round. For rotarded sake (and roughly same price) the racing beat furai triangle muffler looks good.. You are not allowed to view links. Register or Login but I would just to 2.5" all the way back which would be good for my application because I would get great velocity and torque for my midrange which is ideal for rallycross.


Anyone got suggestions or tips?

I'm thinking magnaflow or a glasspack will be too cheap and either rust or be WAY to loud.
« Last Edit: February 06, 2012, 02:06:13 PM by fidelity101 »

Offline ~Groll69~

  • Administrator
  • Rotary God!!
  • *****
  • Posts: 1235
  • Karma: 1
  • Gender: Male
    • Elegant Lady Bridal and Tuxedo
Re: Lets talk about exhausts...
« Reply #1 on: February 07, 2012, 09:57:31 AM »
I dont have enough knowledge on exhuasts to be able to give a proper opinion.  I personally prefer to keep the dual exhuast look and the convertible we have does not have a cat on it.  It also blows out the seal next to the stock exuhuast header.  Any ideas of how to keep it sealed properly there would be great.
"Long Live Rotary"

An RX-7 is like having a slut as a gf! She will love you, but she will also screw around with the guy at the parts store, most of the local cops, your insurance agent, your apex seals, your bank account and your credit card!!!

Offline fidelity101

  • Sr. Member
  • ****
  • Posts: 462
  • Karma: 4
Re: Lets talk about exhausts...
« Reply #2 on: February 07, 2012, 03:06:45 PM »
its the stock exhaust manifold? metal is probably all pitted/rusted/old so it never really seals all the way for a very long time

Offline ITSWILL

  • Rotary God!!
  • ******
  • Posts: I am a geek!!
  • Karma: 9
  • Gender: Male
Re: Lets talk about exhausts...
« Reply #3 on: February 08, 2012, 07:22:05 PM »
A chambered oval exhaust will sound better and be quieter in most cases.  I think the best fc exhaust is the racing beat setup.  I have had that and a 3 in straight pipe with a cart can, I'm sure it it obvious which was quieter and sounded better.  How much power are you planning? I have to imagine unless you are going to be over 300hp you would be fine with a 2.5 in which will have higher exhaust velocity and produce more low and mid range torque than a 3in.
86 Base LS1 w/100 shot
88 TII 20B T70 turbo

Offline fidelity101

  • Sr. Member
  • ****
  • Posts: 462
  • Karma: 4
Re: Lets talk about exhausts...
« Reply #4 on: February 09, 2012, 01:18:23 PM »
You are not allowed to view links. Register or Login
A chambered oval exhaust will sound better and be quieter in most cases.  I think the best fc exhaust is the racing beat setup.  I have had that and a 3 in straight pipe with a cart can, I'm sure it it obvious which was quieter and sounded better.  How much power are you planning? I have to imagine unless you are going to be over 300hp you would be fine with a 2.5 in which will have higher exhaust velocity and produce more low and mid range torque than a 3in.

its a rallycross/rally car so anything 2wd above 250-300hp is useless you just eat tires and loose traction. right now I have the RB street header to a 2.5" midpipe 304 stainless to the RB street NA twin muffler exhaust.

When I get some free time/money I'm gonna swap it over and make a single but I'm just going to have to pick a muffler...

the less weight would be nice and ease of instillation.

Offline bruceman

  • Jr. Member
  • **
  • Posts: 10
  • Karma: 0
Re: Lets talk about exhausts...
« Reply #5 on: February 10, 2012, 09:00:34 AM »
On my autocross S5 FC I have a neader, one cat which is 2.5" diameter inlet/exit, and a Magnaflow single exit on the back.  The magnaflow, also 2.5" in/out, is the longest and largest diameter I could get to fit in that location.
I think the dual exhaust is nice if you want a quieter stock looking exhaust but to me it is just useless extra weight.
Kevin with your ported engine you could install another small resonator/muffler between the cat and rear muffler to quiet it down.  I have thought about doing this but everyone tells me the car is not too noisy so I leave it alone.  If you're not running a cat then a straight through muffler in that location is very necessary. 
When it comes to noise reduction I have found reducing the lengths of straight pipe by installing extra muffler/resonators and using mufflers of the largest volume works well.

Offline ITSWILL

  • Rotary God!!
  • ******
  • Posts: I am a geek!!
  • Karma: 9
  • Gender: Male
Re: Lets talk about exhausts...
« Reply #6 on: February 10, 2012, 06:42:57 PM »
Based on my calculations a 2.5" pipe will flow enough to support ~260 hp.  Any larger and you will begin to loose mid-range power and torque with no significant power gains.

Just run a 2.5" single with presilencer and a muffler. Magnaflow makes some decent stainless components that I would recommend.

Any how sounds like already have this all figured out, post some videos when you get it done!
86 Base LS1 w/100 shot
88 TII 20B T70 turbo

Offline fidelity101

  • Sr. Member
  • ****
  • Posts: 462
  • Karma: 4
Re: Lets talk about exhausts...
« Reply #7 on: February 13, 2012, 07:08:31 AM »
I've been running without a pre-silencer for about a year now, but with a single exhaust, may be a good idea...

then again I don't drive it enough

Offline fidelity101

  • Sr. Member
  • ****
  • Posts: 462
  • Karma: 4
Re: Lets talk about exhausts...
« Reply #8 on: February 17, 2012, 09:18:31 AM »
You are not allowed to view links. Register or Login
On my autocross S5 FC I have a neader, one cat which is 2.5" diameter inlet/exit, and a Magnaflow single exit on the back.  The magnaflow, also 2.5" in/out, is the longest and largest diameter I could get to fit in that location.
I think the dual exhaust is nice if you want a quieter stock looking exhaust but to me it is just useless extra weight.
Kevin with your ported engine you could install another small resonator/muffler between the cat and rear muffler to quiet it down.  I have thought about doing this but everyone tells me the car is not too noisy so I leave it alone.  If you're not running a cat then a straight through muffler in that location is very necessary. 
When it comes to noise reduction I have found reducing the lengths of straight pipe by installing extra muffler/resonators and using mufflers of the largest volume works well.

I thought you had the RB triangle muffler, or is that on your subaru, errr rotaru? :P