Exhaust Dilemma - Want Quiet as Stock

[Longboarder]

Originally Posted by Visceral

I've decided to run the Akra X-pipe, but match it with the Dinan rear section.

The Dinan seems reasonable and the Akra seems like it will take a lot of abuse.

What I hear from you though is that this setup would still be too loud for your 0.0% tolerance.

For me it sounds good enough, doesnt stop local cows from giving milk, and withstands track session that should light the car on fire.

For "reference" comparison, I had the Sharkwerks and BBi on my TTS and thought both were intolerably loud. Now on a Kline inconel setup with Kline inconel equal length headers. I don't like loud. I like good.

Thx brother. How much louder would you say that combo is than stock? And does it rasp at all? I want to avoid rasp.

[SYT_Shadow]

Originally Posted by Longboarder

If I remember correctly that's what SYT_Shadow had on his car when the cat collapsed/clogged to cause engine failure. It wasnt the stock primary cats.

Correct, it wasn't the stock primary cats. The car was also tracked a whole hour at a time which goes far beyond typical parameters.

Just in case though I won't track a stock catted car at that level again

[Adrian g.]

Originally Posted by Longboarder

If I remember correctly that's what SYT_Shadow had on his car when the cat collapsed/clogged to cause engine failure. It wasnt the stock primary cats.

If I recall correctly he had a number of motor related "issues" as well around that time, so the root cause of only one of his cats failing is still unknown as far as I'm concerned. Furthermore, I do not know what brand/spec/quality are the cats he was using. Lastly, there are plenty of stick-ish P-cars running hard on tracks with their factory cats and not failing.

[wheresthetrail]

Maybe the question is better posed as: who makes the quietest catted x-pipe?

There's only a handful of x-pipes with HFCs available, but it's hard to tell which one is quietest from all the exhaust clips out there.

Any idea who makes the quietest catted x-pipe?

[L4ces]

Originally Posted by wheresthetrail

Maybe the question is better posed as: who makes the quietest catted x-pipe?

There's only a handful of x-pipes with HFCs available, but it's hard to tell which one is quietest from all the exhaust clips out there.

Any idea who makes the quietest catted x-pipe?

Do you intend to run it hard with valves closed? Would there be potential for engine damage with increased back pressure with valves closed in the case that you don't want it blazingly loud?

I ask these questions because of a recent conversation where one said stay under 4K with valves closed.

[Bomiz]

Originally Posted by wheresthetrail

Maybe the question is better posed as: who makes the quietest catted x-pipe?

There's only a handful of x-pipes with HFCs available, but it's hard to tell which one is quietest from all the exhaust clips out there.

Any idea who makes the quietest catted x-pipe?

I would say get a resonated + 200cell HFC x pipe.

Or just run test pipes. It's not that loud

[Mvy]

Originally Posted by M3ANMACHINE

Agreed. V Band clamps for the front cats and test pipes would be your best option.

Heres a pic of the welded band set up. I have the version you dont need the doughnut at the header. You get a little leak from time to time and have to be careful if you move the bands at all as the metal epoxy you use to seal it up can crack once it gets messed with. Otherwise its a really great way to switch from HFC to test pipes on track days!



https://drive.google.com/open?id=1zv...oNbCv-BS__0liY

Custom exhausts are so much fun but they add some extra headaches too. You can see how there is not much room in there for anything else diverter wise. Its hard enough to add HFCs and not have it buzz away at the heat shields under some conditions. And a word to the wise, HFCs hang lower than factory cats as they are usually football shaped instead of pancake, and if you have not done motor mounts in a while do that first before you mess with the cats. It can throw things off about half an inch if they are smushed and later changed out causing you to have to revisit the length of your exhaust.

[SYT_Shadow]

Originally Posted by Adrian g.

If I recall correctly he had a number of motor related "issues" as well around that time, so the root cause of only one of his cats failing is still unknown as far as I'm concerned. Furthermore, I do not know what brand/spec/quality are the cats he was using. Lastly, there are plenty of stick-ish P-cars running hard on tracks with their factory cats and not failing.

True root cause analysis is tough to do in the real world. It is very likely it was that, it explains destroying my valve stem seals so quickly

I ran the ESS HFCs. Don't know what brand they are, but they took over 100 track days before breaking. HJS is likely better than the ESS ones but they are also only warrantied for two years so they might have suffered the same fate. Who knows? Do you have comparable use cases where the X-branded cat survived? I don't. So I hesitate to blame the ESS cats.

I challenge your assumption of P-cars running hard on tracks.
First of all they are not running double-duty by two instructors.
Secondly, it is rare to see a Porsche car that is driven hard vs the car's capabilities.

[Visceral]

Originally Posted by Longboarder

Thx brother. How much louder would you say that combo is than stock? And does it rasp at all? I want to avoid rasp.

Let me get it installed and I'll get back to you. It's not on the car yet.

[M3 Number 86]

https://www.m3post.com/forums/showthread.php?t=1535236

[Longboarder]

Originally Posted by M3 Number 86

https://www.m3post.com/forums/showthread.php?t=1535236

I'm in bro. I guess that means we doing ACS on Sunday instead.

[M3 Number 86]

Originally Posted by Longboarder

I'm in bro. I guess that means we doing ACS on Sunday instead.

haven't seen you in a while!

[Visceral]

Originally Posted by Longboarder

Thx brother. How much louder would you say that combo is than stock? And does it rasp at all? I want to avoid rasp.

Now that it's on (Thanks Alex @ Alpine for Stage 2), I would estimate it is about double the volume of complete stock (3dB increase). This isn't trivial to me... if this was an everyday commuter car, I'm too old for quite this much. This is a track car for me, however, and I'm confident it will pass noise around here at tracks. There is no rasp. It doesn't sound un-refined. And it makes less noise than you can hear over tire noise at a steady highway cruise.

When I get on it, the only sound that is a little over-the-top (to me) is around 300-600hz. Like a low midrange. Something a 4-inch driver would be great at. I wouldn't doubt that this is what four cats prevents (instead of the Akra's 2 cats and two resonators) No drone (it's doesn't sound resonant), just more than I'd spend an hour a day with.

Fortunately for me, this car serves only two purposes. My wife likes to drive a nervous loud European car on sunny days. The i8 was too much of a combination of smooth and difficult to charge every direction of her commute if she wanted to stay full electric (which was specifically important to her). The E63 wagon was loud enough for her, but too big. She loves the 991TS but knows we don't want too many miles on it, so we save it for non-commute drives.

The other purpose is as a track and autoX car, and with my helmet on, this should sound great and make great power