TeamRX8

iTrader: (25)

the problem with putting it out the center of the bumper cover rotary is that piece is integral to the whole rear bumper, not a separate piece, so once you cut it up that's it, no going back. Plus the exhaust puts out tremendous heat which will easily melt the bumper material, the exhaust system grows quite a bit and moves around when it's at max temp. You're better off either going out the factory exhaust exit points or just dumping it prior to the bumper cover as I, RB, and others have done. It seems like a neat thing to do, but in practice it doesn't really make sense.

carbonRX8

iTrader: (1)

Update on the custom single outlet exhaust I alluded to higher up in this thread:

Think Talladega, front row, right after turn three just at the begining of the long straight, and you forgot your ear protection. And I never got it up past 4k rpm. I was actually scared to go faster than 55mph. Thought that the secret service was going to bust me cause they thought a Mig 33 was on the way with the afterburners on! I startled myself going under overpasses (actually ducked.) The quality of the sound is great, but it is like an 8 engine, rotary powered 747 at take-off. The definition of too much of a good thing.



I have a B&B test pipe on now (with the obx header). going to try the two cats I have in the closet (one stock, one SR motorsports.)

sstricker

I haven't laughed that hard in a long time!!!! thanks carbon

carbonRX8

iTrader: (1)

WHAT??!?! I CAN'T HEAR YOU!

TeamRX8

iTrader: (25)

a lot of those oval turbo mufflers aren't going to cut it on a rotary, for starters most of them are designed to be noisy with a piston engine, which means they'll be louder still with a rotary, and then you better have stainless steel scrubble packing in there or the heat alone will fry any other type of sound batting, even at the very end of the exhaust system

Fanman

We tested a prototype 3" single exhaust on my car and it picked up +10 ft.-lbs. of tq on a Greddy turboed car. Surprised at the results. Still have my JIC Twin Titanium on my car now though, as it was a prototype/custom unit made by "super secret" company, and I like the way the duals look.

Nemesis8

iTrader: (3)

DITTO THAT!

I went around the block with the RB single, and drove right back to the shop to remove it. With the RP Supercat midpipe it was way too loud. I have the single in the trunk for now with my old RB connecting pipe. When I went to install the RB Single, I thought it would be nice to get the newer connecting pipe on, but now I wish I'd just left the older RB connecting pipe there. Now I have my older connecting pipe and a brand new RB single exhaust.

I should have recorded the sound for you guys - it was freakin awesome at high RPM, but just not for the street. I might travel with it to the track days and install it on the paddock. It would surely get some attention as I drove by at 8,500 RPM

carbonRX8

iTrader: (1)

So despite being rather ill, I could not help but go out and try to salvage my single outlet exhaust attempt. I put the stock cat back on (it has a large cat and a "glass-pack-like" silencer) and I have to say, the sound is quite reasonable. I dont sound like a 150 db race car anymore. To elaborate, I have the OBX header, stock cat, RB connector (will be replaced with stock soon) then a single magnaflow muffler 3'. I think I am quite pleased. Having to put the weight back on the car with the cat, should be MORE than offset by removing the weight at the rear.

Nemesis8

iTrader: (3)

Yes, any weight in front or behind the axles is bad.

TeamRX8

iTrader: (25)

You just need to put a good hi-flo cat and appropriate silencer in the midpipe, it will still probably be louder than the OE cat assy though

carbonRX8

iTrader: (1)

^^^^Agreed. Now to design.

carbonRX8

iTrader: (1)

So here’s the rub.

I have been running around with a catless midpipe. This is probably the only (yes, I said only. Flame me if you want but i dont care) aftermarket exhaust product that produces real, reproducible, feel-able hp gains on a na car. (Please read that twice before you respond) So now I go from RB's well made REV8 to an ok quality, but very small, single silencer to save mega weight in the rear. Problem is, I sound as if I have no silencer at all. So I replace the stock cat which has a large cat and a rather large silencer to get back down to a reasonable sound level (still rather loud. I can imagine some with less tolerance to aural peccadilloes would reject even this level of sound. There is some sympathetic buzzing going on with the plastic panels in the car.)

But now my car is slow!!! I can actually feel it. I would not say that it is slower than stock, just slower than with the midpipe. I can even tell that the car doesn’t rev as quick in neut. as it did with the mid pipe. Feels like I do right now; plugged up (I have a cold.)

On the plus side, the exhaust doesn't stink anymore. I was starting to get annoyed with that constant pig rich exhaust smell.

So what to do? I agree with Team in that I think the only way to go is get a true high-flow cat (all the common aftermarket cats have the same number of cells / unit measured as stock. I checked, Some here appear to have even bench tested the aftermarket cats and found that they did not flow as well as stock. Dynos proved the bench test.) and put this in line with a large straight through silencer (with steel scrubble as Team mentioned) just like the stock set-up. Hopefully this will get me back up to the level that I was getting with the mid pipe, yet allow me to dump weight in the rear.

Ironic ain’t it?

ddub

How about the B&B midpipe with a non-RB catback? Something that isn't extremely heavy?

For example, the weight quotes I've gotten from the rx8store catback are the SAME weight as the RB SINGLE. It is a fairly light dual catback, but not super light like titanium would be. I'd go something that route probably. Keep the midpipe, get a dual catback that is light but reasonably priced.

Fanman

carbonRX8,

When I dynoed my SR Motorsports w/ silencer installed I picked up 4-5 hp across the rev range. Unfortunately I sold it, as it was popping with the Greddy turbo unit. Went back to the stock cat, which helped. But then I swapped out my FMU later & would/should have kept the SR unit. Definitely not as much as the 8-9 hp that the midpipes that were tested but it was also much quieter than the current RP hi-flow cat that I have (which seems to flow a bit better than the SR unit, but is louder).

ULLLOSE

iTrader: (1)

Someone should have done a search:

This is an old post of my system: https://www.rx8club.com/showthread.p...single+exhaust

Here is a guy that used my setup: https://www.rx8club.com/showthread.p...single+exhaust *pics and video in this one

Single side exhaust...

--------------------------------------------------------------------------------

I have had a few inquires about my single exhaust so here is the info: Built it myself, borrowed a small portable wire feed welder, cut some bends and went to work. As you look at the pics be nice, I am not a great welder. It is possible that you could do this system with clamps if you do not have a welder, but you would most likely have some leaks as clamps never seal that good.

pics: http://www.cactus.org/~edj/rx8club/muffler/

I cut off the stock muffler about 6" down from the slip fit at the muffler. Then used the U bend to make a large curve, around 110', into the muffler the other end slips over the stock cat-back pipe. I have the muffler tilted up slightly as it goes from the center of the car out. Then cut the J bend at 90' to make your exit. Keep in mind you need to make the exit long enough that it clears the plastic area of the bumper. With the single exhaust there is A LOT of heat coming out of that one pipe and you can melt the plastic if you are not centered in the opening or you make it to short. For a tip I just cut the end of the pipe at about 30' and painted it black with high temp paint. For a hanger I used a piece of 5/16" round bar from Lowes. I bent a 90' on each end, making a squared off U shape, so that it would line up with the factory hangers on the passengers side then welded it to the top of my outlet pipe.
I do not have any HP/Tq info on this system. Due to the lack of credible dyno numbers, damn ECUs, I did not bother with dyno runs. I figured it was not important to worry about a few HP, as most after market systems make 2-3hp, I just look at it as saving 22lbs.
I do not have a DB reading. I can tell you at the San Diego Natl tour they were monitoring Dbs and I was no where near the 93db limit. There is another RX8 in SD with a single side system using the 12" long XR-1 and it has hit 93db once, may have been a fluke as it usually is under, and my car is significantly quieter. I know a few members were in SD and may have heard the system and could comment. Also while in AZ I had a couple of members ride in the car at an autoX and they might have sound/volume feedback as well.

All of my parts came from Summit Racing: All parts are 2 1/2" diameter.

Borla XR-1 16" long: PN# BOR-40942 $132.95
Summit U bend: PN# SUM-622003 $16.95
Summit J bend: PN# SUM-621008 $16.95

TeamRX8

iTrader: (25)

all that stuff is way too heavy though but oh so much cheaper

kw1k

I would also personally want a single exhaust, they obviously flow better. Weigh less.

I would be really interested though in a single exhaust unit.

Hi Flying 8

iTrader: (2)

I just had a single exhaust made for me by 3R Racing that weighs a total of 12 # for the whole cat back. I had it dynoed before and after and gained 7 HP and 5 ftlbs and this is at over 5000ft, so results should be much better at lower altitudes. 3R used their extensive racing design experience in creating a very smooth transitioning (from 2.5 to 3") and flowing exhaust. They have been racing in the SCCA World Challenge with Porsches, Vettes and last year, Vipers and this is the type of exhaust they build for those. They were the 2004 GT champs and last year's runnerups, so they have been very successful. Also, the designer was the 2004 EP SCCA Nat'l champion-Chris Dorsey. (Call him for info) You can see and hear the exhaust at:
3rauto.com[/EMAIL]

It sounds deeper in real life than it does on the website, but you can get a good idea.

Nemesis8

iTrader: (3)

Not bad. My single is sitting in my basement waiting for track days this summer. It's way too loud for a daily driver.

ddub

Got any pics Hi Flying 8?

EDIT:
Nevermind, found it on the site http://3rauto.com/gallery_folder/rx8...8_exhaust.html

That is a small *** muffler/resonator you used! No wonder it's so light. I'm surprised it's not louder too.

TeamRX8

iTrader: (25)

I just love it when people throw around Solo2 champion names like that makes some kind of difference or something try to remember that 3 months after winning they are officially ex-champions

https://www.rx8club.com/rx-8-racing-25/sweet-sounding-new-exhaust-12-a-81562/

Hi Flying 8

iTrader: (2)

Ex-Champ or Champ, they still won and that fact gives them credibility. It also guarantees that they are talking the same language as other autoxers and can more likely get you what you need than some hack shop down the street.

TeamRX8

iTrader: (25)

yeah, right .... that's why it weighs 12# instead of 8 or 9#

Hi Flying 8

iTrader: (2)

If the only way you judge the quality of workmanship is by weight, then you would be right. However, this exhaust was engineered to give max flow with the smoothest possible transitions and to avoid the need to be replaced next year. This is the way I want it in order to avoid having to worry about future problems and expenses. I wouldn't disparage someone's work because of three pounds, without knowing a little more info before making that kind of judgement.