New custom exhaust system fabrication

[Lane]

Over time, my stock muffler has been getting louder and raspier - so much so, in fact, that I can't hear the supercharger whine under WOT from the driver's seat.  I finally did something about it recently and found race fabrication shop that was nearby willing to tackle the job.  My goals were a 3" diameter piping, from-the-factory (smooth & understated) look with routing & mounting, no interference with roll bar or wing mount (both of which may end up on fabrication list in the future), and ability to swap mufflers quickly.  Plus, it had to fit within the confines of the rear frame area.

A close inspection of the stock header showed it to be in good health, and the tubing diam looked pretty well-matched to the head exhaust port size so I chose not to mess with it other than adapting/enlarging it to the new flange & puttng on a new O2 bung.  Pic just after fabrication was completed:



After I painted the system and did the preliminary buff job on the muffler:



I'm not quite finished buffing the muffler so excuse the haze on it for now. 

There are quite a few more picture in high-resolution and a video clip showing what it sounds like in my website's gallery here.

Overall, I couldn't be happier with how it turned out.  Some of the clearances are tight, and I plan adding a bit more heat-resistant wire shielding where appropriate just to be safe, but there ended up being sufficient clearance between all powdercoated frame tubes.  In retrospect, I doubt the flex section I chose to use was even necessary for anything other than to ease installation.  The Borla muffler on it now isn't the quietest but sounds very good under accel, and it has a burble under decel reminescent of a V8 that just sounds outstanding.  The cost of all the parts and labor was quite reasonable.  Since the aftermarket system I've seen offered in other threads didn't quite suit my needs (even though it is listed as offering more features/benefits), I'm glad I went this route.  Heck, if I compare the two, this custom job turned out to be a bargain although it's probably not something a non-DIY'er Atom owner would want to do since it did require planning, separately sourcing parts, finding a capable & reputable shop, disassembly & painting, buffing, etc.  But for someone who is hands-on, the reward was worth the effort.

If anyone would like info on the shop in central WI that did the fabrication work, send me a private message and I'll put you in touch.

[Wmcmanus]

Looks great, Lane.  As you say, for someone who is not DIY-capable, it's probably not an option.  Otherwise, I'd be all over it.  I'm still thinking about what to do with my exhaust, and will probably go with one of the more turnkey options.

[1965Cobra427]

Looks really clean and nicely fabricated. I'm looking forward to hearing your experience with it over time on the track and on the road. The Borla has tobe a big improvement over the OEM muffler in terms of durability. I like it!

[silver]

Looks really good....if you end up need to replace the headers, you might have them do a new design, here are the following issues with the design of the stock header

1:  the header primaries don't actually line up with the exhaust ports, therefore even though they are roughly the same size, the air coming out of the exhaust manifold is actually blowing into the header flange rather then completely in the primary tube.
2:  the header bend radius are all too tight and therefore do not pass heat through efficiently
3:  The o2 sensor is too close to the the exhasust ports and it's  getting too hot and doesn't accurately send information to the ECU.  This causes the car to run rich and wastes fuel.

It's too late now to make these changes since your exhaust system is complete....but if you ever want to change the header, these are the recommended changes to be made to improve on factory.

[Wmcmanus]

[quote="silver"]
Looks really good....if you end up need to replace the headers, you might have them do a new design, here are the following issues with the design of the stock header

1:  the header primaries don't actually line up with the exhaust ports, therefore even though they are roughly the same size, the air coming out of the exhaust manifold is actually blowing into the header flange rather then completely in the primary tube.
2:  the header bend radius are all too tight and therefore do not pass heat through efficiently
3:  The o2 sensor is too close to the the exhasust ports and it's  getting too hot and doesn't accurately send information to the ECU.  This causes the car to run rich and wastes fuel.

It's too late now to make these changes since your exhaust system is complete....but if you ever want to change the header, these are the recommended changes to be made to improve on factory.


[/quote]

Were these considerations taken into account in the Shinoo/Hytech exhaust design?  That's the one that has my attention at this point, although it's starting to seem expensive now that I'm losing multiples of their asking price every single day in these terrible market conditions.

[silver]

Personally I don't know but we took these into consideration when making the fortress exhaust....I'm sure the hytech exhaust fixed most if not all of these issues. But hytech didn't use a 3" exhaust. Just in case that matters to you

[Wmcmanus]

[quote="silver"]
Personally I don't know but we took these into consideration when making the fortress exhaust....I'm sure the hytech exhaust fixed most if not all of these issues. But hytech didn't use a 3" exhaust. Just in case that matters to you
[/quote]

Ok, gotcha.  Fortress is the other one I've been reading about.  None of it makes much sense to me, so having a 3" exhaust isn't an absolute must.  Guess I'll just have to keep reading and try to make a good decision one day.  Obviously, we'll all eventually have to replace our Brammo Atom 2 Ecotec exhausts.  I'd prefer a roll bar and rear wing friendly solution that won't break the bank, will perform flawlessly (as in won't blow out in short order, not as in something that enhances dyno results) and looks at least decent. 

[silver]

I don't know if you can even buy a fortress one at this point.....no one has mentioned it in a while but last I heard folks were having difficulty communicating with him.

I can tell you this...most people were not that pleased with the look of the welds on the fortress exhaust...but for me, I could care less. it works and it's bullet proof...at least so far.  It uses 100% 13mm bolts there's no need for a wobble extension anyone can install / remove the exhaust with a standard 13mm socket, it solved every single performance issue with the stock system, and was designed to work with the wings and roll bar.

The only 2 parts Ray didn't do himself was make the muffler which was handbuilt by another company, and the ceramic coating....which has discolored or peeled off on a few systems.  I really think he could have made prettier welds but since he has a full time job I think there just wasn't enough time in the day for a project that size.

Making one exhaust for 1 car isn't so labor intensive but when you make a design that solves every single issue it takes many many attempts before you get it right.

[bolus]

looks good.  I'm surprised you stuffed a 3" one in there.  Definitely get some gold fail or some of the stuff DP used to protect his fuel tank from the exhaust.

I think the idea of using a repackable exhaust should always be considered.  since the muffler on pretty much any solution is eventually going to get destroyed on our cars, a cheep fix would be a good one.  Look at Darth, he has that giant high flow muffler on his 3" exhaust and it is already blow completely out. 

[silver]

Or get a muffler with no packing and only 18 gauge metal baffles inside....that way there's nothing to wear out!

[positron]

Looks nice Lane..

Nothing wrong with a 3" exhaust >20 track days with this one... I'd go bigger if they could bend it. I was so put off with the flex(s) I decided no flex... I tried 2.5" and was still too small for track use and too loud for Laguna Seca..

However, my unintended trade was.. no room for a wing mount.... so Huzzah for you.. It will mellow out some after it settles in.

[Lane]

[quote="silver"]
1:  the header primaries don't actually line up with the exhaust ports, therefore even though they are roughly the same size, the air coming out of the exhaust manifold is actually blowing into the header flange rather then completely in the primary tube.
[/quote]

Mine looked OK in this regard - at least when comparing the header ports to the gasket.



[quote="silver"]
2:  the header bend radius are all too tight and therefore do not pass heat through efficiently
[/quote]

Good to know.  Is this theory, or has someone done some temperature measurements between the stock header and something other?

[quote="silver"]
3:  The o2 sensor is too close to the the exhasust ports and it's  getting too hot and doesn't accurately send information to the ECU.  This causes the car to run rich and wastes fuel.
[/quote]

Wouldn't the original ECU tune compensate (assuming they tuned a/f with the sensor in that position)?  Or is it suspected that the sensor reading goes totally screwy?

[quote="bolus"]
I think the idea of using a repackable exhaust should always be considered.  since the muffler on pretty much any solution is eventually going to get destroyed on our cars, a cheep fix would be a good one.[/quote]

Borla does have the million-mile warranty on their stuff.  Might just be high enough quality to last... we'll see.  Positron's still being together with 20 track days is good news.

[quote="silver"]
Or get a muffler with no packing and only 18 gauge metal baffles inside....that way there's nothing to wear out! [/quote]

It'd be nice to hear a muffler of that design on our cars, as I wonder if it would effectively suppress the hi-freq rasp.

[McFred]

[quote="silver"]
Or get a muffler with no packing and only 18 gauge metal baffles inside....that way there's nothing to wear out!
[/quote]

In one of the other threads on this I think someone said that the aae mufflers have no packing:

[silver]

if you look really closely you can see where they welded in a straight piipe instead of the flexible section at the bottom HAHA

[atomaker]

AAE cars use a slip-joint (without spring retention) vs. a lower flex coupling.  By comparison, Atom 3s will use only spring retention slip-joint downstream of test pipe/muffler combo; no flex couplings.

AAE re-packable SS mufflers are from Coast Fabrication.  Can be re-packed with either glass mat, or SS shavings (longer lasting), but both are loud.  Zero exhaust system failures since changeover. 

In WOT drive-by (@ 50'), a typical 245 HP AAE car records up to 108 dB (used muffler packing).  New packing = - 3 to -5 dB.  Under the same conditions a new, stock 300 HP Atom 3 just recorded under 90 dB, with +/- changes in dB having exponential effect.