exhaust diameter..

[jeffp477]

ok guys who knows the diameter on the oem exhaust for c5 2.7t... need it. pls..

[4ringAR]

i think it is 2.25" OD. but dont take my word on that.

[jeffp477]

i think it is 2.25" OD. but dont take my word on that.

that what it looks like, but i want to make sure... still trying to do research, very hard to find info on this.. thanks. though..

[2001A6]

the 2.8 is 2" OD.

[awtst3.a6]

i think it is 2.25" OD. but dont take my word on that.

ding ding +rep

I believe the s4 has 2.5 piping vs. the a6

[jeffp477]

ok so far the only thing i found.. oem a6 has a 50mm diameter which is about 2inches... well it is 1.97 and a bunch of numbers following that but ill stick with that which is considerable for a 2"... lol.. so the stock a6 is losing hp cause of flow, not like their brother s4 that has the same 2.7t engine which AWTST3.a6 mentioned that it has 2.5.. well that sucks..

[4ringAR]

that might be the diameter of the 2.8 exhaust. i will go out to my car in the next day or 2 and see what the circumfrance of the tubing actually is and then find the diameter.

[Mantis]

The S4 and A6 have the same diameter downpipes, the cat back exhaust is 2" ID not 2.25", I promise you

[awtst3.a6]

ok so far the only thing i found.. oem a6 has a 50mm diameter which is about 2inches... well it is 1.97 and a bunch of numbers following that but ill stick with that which is considerable for a 2"... lol.. so the stock a6 is losing hp cause of flow, not like their brother s4 that has the same 2.7t engine which AWTST3.a6 mentioned that it has 2.5.. well that sucks..

Ehhh, with 2.0" piping it doesn't limit what you can do and isn't always a disadvantage. Some people set cars up like this for back pressure (on a turbo'ed car). My guess is audi did research with the 2.5 before they looked at the 2.0". They prob sound out that there was a lack of back pressure with the amount of piping used in the a6 vs s4. Causing them to go with smaller piping which in this case for our car might be better. I understand higher flow = more horse power but that doesn't mean you will be boosting off the line :D.

[awtst3.a6]

The S4 and A6 have the same diameter downpipes, the cat back exhaust is 2" ID not 2.25", I promise you

it is 2.25" OD and 2.00" ID... I have messed with my exhaust 3-4 times. :D The s4 is 2.5 OD and prob 2.25 ID... Leaving a .25 inch difference which is huge in exhaust talk. Yes the cars do have different piping.

[mike's machine]

C5 2.7 2.25"
b5 s4 2.50"

[Mantis]

I deleted my mufflers, the exhaust tubing I had to buy to put in place was 2" ID, so either I got really screwed on my factory exhaust, or the A6 2.7t came with 2" exhaust, I also believe that the S has the same size exhaust, since I am running S downpipes to stock OEM straight pipe axle back

[mike's machine]

B5S4 has 2.5" OD tubing including the DP's.
so your 2" ID is the same as 2.25" OD...? and your S4 DP also is 2"...?...hmm

[Mantis]

Then read what I posted before commenting, I clearly stated ID, that is how you measure exhaust tubing, by the amount or space open inside the tube, not outside the tube

[mike's machine]

so whenever we talk about exhaust diameter, it's ID...?
but we always say we have 2.25" and S4's have 2.5"...which are OD...

[awtst3.a6]

so whenever we talk about exhaust diameter, it's ID...?
but we always say we have 2.25" and S4's have 2.5"...which are OD...

to nothing:

You say OD..... ID is a given. What are you going to bitch about next? HP vs WHP? Stop being so technical to make your self right.

[Mantis]

My experience is that Audi calls it by ID, so that's how I call it. It always sounds better to state the OD as it is bigger, sounds faster.

[awtst3.a6]

My experience is that Audi calls it by ID, so that's how I call it. It always sounds better to state the OD as it is bigger, sounds faster.

No.. it is just nice having your exhaust connect together vs all of the shit/clamps you would need to do to get a smaller OD exhaust to work (with the same ID)... If you didn't measure both OD/ID before ordering parts/piping... you aren't smart.. How else do you piece a exhaust system together.... annnnnd on the topic yahhh that is why they call them 3.0" exhaust for the s4's.... They sound bigger stronger(from a sales stand point)....What are they relating to when they say 3.0" exhaust? OD? not ID..... I don't think anybody here is claiming that 2.25 inches is big/bad/faster.... I think you just need to chill out.

[Mantis]

I am only trying to point the OP in the right direction, which I see he was alreday doing himself. I am very chill, I just dont want to see some poor guy order a bunch of tubing, only to find out it is not what he is looking for. I always stated that I was speaking in terms of ID, check my original post. I was not wrong, we apparently just have a different view of how to size exhausts.

[awtst3.a6]

Let me refresh you how this happened again....

i think it is 2.25" OD. but dont take my word on that.

I agree with 4ring_jelly "2.25 OD" as quoted...

Then you go along the lines saying.....

The S4 and A6 have the same diameter downpipes, the cat back exhaust is 2" ID not 2.25", I promise you

??? So stop being technical. You say 2.25" is wrongin the quote in relation to the previous post by 4ring and i? Yes or no. You then try to turn the tides with ID vs OD... Honestly just stop.

Now you have mislead the OP and he is confused and unable to get help from the forum. Congrats. Also I measured the ID/OD when I got my piping unlike you(car exhaust off). So how would u even know.




Notice how the apr 2.5 piping fits to the stock exhaust (2.25). It is just a piece of exhaust but you can see it needed a good bit of weld to fit.

[Mantis]

I am truly sorry that you feel I mislead, I just found that OTS 2.25" OD was a sloppy fit when I was putting my exhaust together. That is why when I ordered my parts, I ordered 2" ID. There is no need for name calling, I am aware that you and I have a history on another forum, but let's not bring that over here.

[wofman]

Jeff -

I assume you got all of the above. What are you thinking of doing?


wofman

[Mantis]

Thanks for the reality check Wofman, back to the OP, what are you thinking about doing?

[2001A6]

One last thing, we didnt get screwed on pipe size, remember the C5 has true duals, where ther S4 does not. pipe might be slightly smaller, but I bet the flow volume with duals and not is pretty similar.

Sam, thats how mine looks from stock to 2.25 inner.

x3 what is op plannign to do....

[4ringAR]

One last thing, we didnt get screwed on pipe size, remember the C5 has true duals, where ther S4 does not. pipe might be slightly smaller, but I bet the flow volume with duals and not is pretty similar.

THIS.


the math:
if the A6 has 2" ID x 2 pipes: pi*(ID/2)^2 = pi*(2/2)^2 = 3.14 x 2 = 6.28 sq inches

if the S4 has 2.25" ID x 1 pipe: pi*(2.25/2)^2 = 3.98 sq inches

[Mantis]

I was only being sarcastic about getting screwed on exhaust sizing, I did the same math that 4 Ring did, that is why I opted to stay with stock sizing on my muffler delete. I think that the flow is sufficient to sustain stage 3 power at the altitude that I am at. However, for depth of sound, I wish I had gone with 2.5" ID, the 2"ID tends to be slightly raspy at part throttle

[jeffp477]

Jeff -

I assume you got all of the above. What are you thinking of doing?


wofman

well thanks to all the help guys...

and yes wofman figured out what i'm planning to do... like nothing77 says, the 2 inch is ideal, but i think i'll be running 2.25 from the cats still debating to put x2 resonator or an x-pipe for the droning noise, no mufflers, just putting tips... so it wouldnt look ugly at the rear seeing stainless steel.

so what do you guys think about that setup?

favor on resonators or x-pipe..

[2001A6]

THIS.


the math:
if the A6 has 2" ID x 2 pipes: pi*(ID/2)^2 = pi*(2/2)^2 = 3.14 x 2 = 6.28 sq inches

if the S4 has 2.25" ID x 1 pipe: pi*(2.25/2)^2 = 3.98 sq inches

lols, it was late. I think the A6 has more restrictions in the system, S4 has 2 suitcase mufflers/resonators, and the A6 has the big res, the small res, and 2 mufflers.

Also, the S4 has duals up to the res, then its single, there fore it is alot closer than that figure.


I now have an x pipe. Kills the drone, but not sure on the sound. Inside the car its great, but is real raspy outside.

[jeffp477]

I now have an x pipe. Kills the drone, but not sure on the sound. Inside the car its great, but is real raspy outside.

i guess ill do the combination of both 14" resonator and x-pipe with no muffler just tips..

but how raspy does it sound? i need to hear it though...

[2001A6]

I have video footage, just need to load it onto youtube. I will post it for you.

[jeffp477]

I have video footage, just need to load it onto youtube. I will post it for you.

that is so cool... i know kievisky has a nice setup, but he running with no cats, and his running a full custom set up too..

thanks..

i'm adding you of my fl.. are you on the facebook acct that kievisky made for the c5's?

[2001A6]

yep, I am. and no problem, videos are up loading now.

Previous set up.. Remus mufflers, resonator delete, all cats, no x pipe. Droned like a bitch! but sounded amazing outside...

sound starts at 30secs, skip to that.
http://www.youtube.com/watch?v=8h42DObnBmM

[jeffp477]

yep, I am. and no problem, videos are up loading now.

Previous set up.. Remus mufflers, resonator delete, all cats, no x pipe. Droned like a bitch! but sounded amazing outside...

sound starts at 30secs, skip to that.
http://www.youtube.com/watch?v=8h42DObnBmM

cool.... thanks for the vid clip...

[2001A6]

And this is new setup.

http://www.audizine.com/forum/showthread.php?t=330617

[ccomengee86]

2" ID. At least on my allroad.

[wofman]

I opted for engineered catback system (Milltek -- used, fortunately for the purse) behind AWE DPs, so I didn't have any risk or uncertainty re sound/drone or with performance (clean and mean). Milltek uses resonators and mufflers -- no drone, no rasp. Not as aggressive as most folks here might want. More of a low, gentle growl.

[jeffp477]

I opted for engineered catback system (Milltek -- used, fortunately for the purse) behind AWE DPs, so I didn't have any risk or uncertainty re sound/drone or with performance (clean and mean). Milltek uses resonators and mufflers -- no drone, no rasp. Not as aggressive as most folks here might want. More of a low, gentle growl.

that sounds like a nice set up as well. im still quoting about putting cut offs on mine for the cats..

[khalimadeath]

I got the same problem ive been searching and came across this thread seemed logical to just add to this thread. what is the OD and ID on an 01 C5 4.2 cause i cant find that shiz anywhere

[pit viper]

I opted for engineered catback system (Milltek -- used, fortunately for the purse) behind AWE DPs, so I didn't have any risk or uncertainty re sound/drone or with performance (clean and mean). Milltek uses resonators and mufflers -- no drone, no rasp. Not as aggressive as most folks here might want. More of a low, gentle growl.

I had a cat go bad on those piggies, and ended up just getting them cut out for now. So, piggies with gutted pre-cats, straight pipes instead of the larger cats, and 2.5" pipes back to Magnaflow's. A little more aggressive than I want, but until I save up to get a good set of downpipes...