potential exhaust restriction

[silver]

I also have the philosophy to drive it hard right out of the gate.....but mine dyno'd at 220hp at 500 miles.

do you mind sharing what your dyno numbers came in at before and after the exhaust rather than just the difference the exhaust made.  oh yeah...Congrats on making such a marked improvement too that's quite impressive.

[positron]

Mine was a VERY disappointing 210hp at 93*F ambient stock. Plugs and pipe very black.

With 2.5" 222hp at 108.9*F with 91 octane
224hp at 105.4*F with 100. (same day)(is 100 worth it? IMHO no.. especially with current conservative timing map. But if we can get it to stay in hi octane map.. well see)
*temps taken from dyno sheet. Plugs and pipe clean. Switching to copper electrodes this weekend.

I'm hoping with the 3" and cooler ambient temps and now with AFR's at a more appropriate level it'll start to shine. I'm trying to stay with my original stage 3 kit as long as possible. I believe the upper level timing is much too conservative.

[silver]

GULP.  geebus,

well more questions, did you just have an exhaust shop fab up a new exhaust for a couple hundred bucks (2.5") or was it more involved?

[positron]

Point of clarification, I dyno'd on the same dyno at the same track about mid-day during multiple track events, which may validated "pooping out" at the end of the track day/session. However, the second had a much hotter ambient temp, so I would expect the "pooping out" to be more pronounced. Conversely I have not dyno'd out of the box when everything is cold. Which to me is irrelevant except for forum racing. I intentionally tested during a track event because this is where I solely operate the vehicle as that is it's sole mission. Also at hand I am/was intently interested in getting this car down below 92dB so that I can run at Laguna Seca.

I was fortunate enough to be considered by Borla's R&D department to test various configurations, which I am quick to point out I am no way affiliated. If appropriate and if there is some interest I could post the email contact in the clubroom so they could gauge interest in providing a product to the group.

[silver]

AND.......next question, is the exhaust mandrel bent or just standard bent.  Basically what I'm getting at is that the local muffler shop will make an exhaust for a car for around $200 bucks but they don't have a mandrel bender, therefore, I want to know if the gains you've seen were from Borla simply making an exhaust at 2.5" or if it was because Borla spent mega bucks designing a purpose built mandrel bent "badass" exhaust.
 
Obviously I'm hoping for an answer that would support me going down to the local muffler shop and having them make an inexpensive exhaust to be used on the car that will allow it to breath properly without costing a lot of money.

[positron]

I'd like to think it was all of the above.. I think we already got the "inexpensive" one.

Mandrel, I'd be surprised if local muffler shop is able to bend large pipe these tight radii. Now that said, any increase in wind flow no matter who makes it will/should yield some improvement over the shiny can AND my quest to run this car at Laguna Seca (without getting black flagged and sent home and/or getting the $1,000 per lap penalty if ignored.) To me, the potential cost of losing my $300/day entry fee plus transportation fees etc etc gives me some seed money potential to make better/make quiet(er).

[Myerfire48]

Pos-

Is that photo of the 2.5 or 3"?  And did Borla fab the entire system?  Were you able to utilize the Brammo 'goat head' header or did you build from the exhaust ports back?  I'm thinking the exhaust is too small as well since I'm constantly blowing flex couplers as a result of (I believe) overheating due to the 2.25 constricting the exhaust.  If Borla is currently developing a 3" system it would sure save me a ton of fab work and I'd be in for one immediately.  Please pass that info along and if something does develop let me know.  This car needs at least 2.5 Im thinking 3" could only be better.  Opening up the exhaust should lower the heat soak in the charge as well contributing to the late session 'pooping out'.  Darth and Bolus are talking about water injection in the charge which is a good idea but I think the problem is more attached to the exhaust creating additional heat as a result of being undersized.  Anyone developing a 3" system with a muffler can count me in for one.  Under 92db is just a bonus.

[Terry Kennedy]

[quote="Myerfire48"]
I'm thinking the exhaust is too small as well since I'm constantly blowing flex couplers as a result of (I believe) overheating due to the 2.25 constricting the exhaust.[/quote]

I have an early Brammo Atom with the single-flex exhaust, and I asked Brammo if it needed to be replaced with the upgraded one. They said I had an early one that didn't have the problem of the flex separating. I have 10,000+ miles on the car w/ no exhaust problems.

[Kempo]

How many of the 10,000 miles are from track use? I never had a problem with mine until my first track day.

[quote="Terry Kennedy"]
[quote="Myerfire48"]
I'm thinking the exhaust is too small as well since I'm constantly blowing flex couplers as a result of (I believe) overheating due to the 2.25 constricting the exhaust.[/quote]

I have an early Brammo Atom with the single-flex exhaust, and I asked Brammo if it needed to be replaced with the upgraded one. They said I had an early one that didn't have the problem of the flex separating. I have 10,000+ miles on the car w/ no exhaust problems.
[/quote]

[bolus]

no problems with mine (except flaking cermaic) after 3 track days

[positron]

Terry, 10k holy smokes on multiple levels.. You have the good "one", I'd stand pat. I blew out the flex coupling and flange gasket at my second event in the first 200 (track) miles. After 400 or so miles I blew out the guts of the shiny can, but not ever taking it off I don't know if it even had any as when I did remove it sounded empty with only some rattling sound as if some slag was caught inside. Which means my car had a high proportion of WFO applications early in it's life.

Disclaimer - I'm not a exhaust engineer nor do I profess to have any knowledge of any sort.
I don't agree with the attachment points of the stock system, it's contrary to conventional wisdom. The flex (which is meant for misalignment not flexing) is retained between two rigid points on the motor, the flange and a lower bracket on the motor. The shiny can is held rigid (depending on the tightness of the bolts) to the frame. I see no accommodation for movement or normal flexing, all be it minor. My desire was to allow some motion of the assembly separate from the rigid chassis. This was accomplished by using neoprene mounts to the frame. This system has no braided alignment couplings, the neoprene hangers isolate from rigid frame.

Myerfire, This thread pic is the 3" which is the second iteration. Both iterations where down pipe on.

The first iteration was 2.5" to use the existing header collector and flange. However I found that I still was blowing out flange gaskets. I believe the gaskets to be burning out and then blowing out. During my pretrack inspection I noticed that the gasket was white ashy, which then blew completely out relatively soon while on track. I was ready to place an all copper gasket in it's stead but during reevaluation with Borla I suggested a 3" diameter pipe to further reduce back pressure and a ball/sleeve connection which will eliminate the gasket. This required cutting off the collector and rewelding a 3" ball sleeve assy. Since my coating was pretty nappy looking anyway I figured no harm to cut and weld.

I'm thinking the market needs to bring a 2.5" to mount up without weldment and a 3"+ "done right" affair. I figured the cat supplied was crap, (which may not be cat's fault given crap tune and small pipe) so none was provisioned for as my car is solely a track car.

I'm not sure what dB at 50' is yet, I'm hoping to collect some readings at Spring Mt next weekend.

I don't care for meth/water injection, it seems appropriate for intermittent use ie the drag strip, which will still need and appropriate tune to make best use of it, but for full on track use if you run out of juice with an appropriate tune bad things can happen. I'm sure many will disagree but this was explored with the supercharged Z06 LS6 CTS-V group (which I have over 40 track days on). Which I also chose not to install.

[maverick1]

My lower flex pipe went after my second track day. I just hope the fix Brammo sent me does the trick, however I would definitely be interested in a 3" exhaust that is a little quieter.
Bolus, you need to push your car a little more on your next track day in order to blow out your flex pipe...LOL LOL
I was told that all the Atoms from the AAE all blew out their exhausts, probably due to being thrashed on the track daily. The new fix was first tested on the AAE Atoms and proved to hold up so then Brammo started sending these new exhausts to it's customers.
Cheersâ?¢

[bolus]

well, I also had brammo dyno my car with umptine dyno pulls and the exhaust is still fine. 

[maverick1]

[quote="bolus"]
well, I also had brammo dyno my car with umptine dyno pulls and the exhaust is still fine. 
[/quote]
Bud, I know you drive your car hard on the track....I'm pulling your leg. I'm just really surprised that your Atom and Terry's Atom's exhausts has held up so far. Are you interested in the 3" exhaust?
Cheersâ?¢

[Bruce Fielding]

My braided one lasted a very long time (three years) before it went this year...