Questions about exhaust sizing (GENERIC!!!)

JeffM · Post by **JeffM** » Mon Feb 08, 2010 12:40 pm

First off: I DRIVE AN AUDI!

Alright, so this isn't specifically Neon related but, in general, it's an exhaust question that I'm sure most of you can figure out.

I'm planning on going 2.5" piping all the way back from the cats to the muffler. However, Magnaflow only offers mufflers in 2.25" and 3" inlet sizes. If I were to slap on a 2.25" muffler (since they look better than the 3") wouldn't that defeat the purpose of the 2.5" piping? I've always thought 'A chain is only as good as it's weakest link.' So, would it be more beneficial to go 2.25" piping then?

Post by **racer12306** » Mon Feb 08, 2010 1:02 pm

It probably would be more beneficial to keep it the same size, or look at a different muffler.

excon · Post by **excon** » Mon Feb 08, 2010 7:16 pm

trubendz offers a nice kit at 2.5 inches and a magnaflow muffler. I wish I had seen this after they dropped the price!!

http://www.mandrelexhaustsystems.com/se ... UST/Detail

OB · Post by OB » Mon Feb 08, 2010 7:22 pm

This has been discussed at least 24375 times, but we can do it again I suppose.

Unless you are flowing a ridiculously large volume of exhaust, there is NO NEED to get larger piping. It has been proven to actually hurt performance in many different cars on the dyno. Believe it or not, the 2.25" exhaust is already probably larger than needed for this small engine. Even with a mild engine build, the stock diameter is more than enough.

You mention the muffler as being a possible bottleneck. Take a look at the exhaust ports in the head...

Post by **racer12306** » Mon Feb 08, 2010 7:26 pm

Guys, he has an Audi. This is generic question about maintaining the size of the piping throughout the entire system.

This is not an exhaust size question.

Post by **occasional demons** » Mon Feb 08, 2010 11:12 pm

A smaller exit may not hurt. It depends on how long the gases have to travel. If they cool, the smaller pipe size will help maintain velocity.

A huge exit also lets the same atmospheric pressure that forces air into your intake, push better into the exhaust. You have to think of it as a column of air just lying on it's side. The column = mass. It takes energy to move that mass. When the velocity of said mass slows down, it becomes a "restriction" in that it is taking more power to push it along the tube. You just need to find a happy medium between the needs of normal driving vs WOT driving.

esteinmaier · Post by **esteinmaier** » Mon Feb 08, 2010 11:25 pm

I say open runner like a big block on nitromethane. It will be faster.

excon · Post by **excon** » Wed Feb 10, 2010 11:44 am

I see that you have an '01 SE. To address OB's comment, yes, the exhaust ports on the head are smaller than on an r/t. If you purchased an r/t exhaust manifold it would help. However, you are correct in that a major bottleneck on the exhaust track is the muffler. I'm not sure about the piping sizes between 00-02 because it's been discussed so many times i've stopped paying attention.

Something about going to 2" at the rear axle...

Post by **racer12306** » Wed Feb 10, 2010 11:57 am

Jeff doesn't have a Neon.

He has an Audi.

neonslg09 · Post by **neonslg09** » Wed Feb 10, 2010 12:28 pm

racer12306 wrote:Jeff doesn't have a Neon.

He has an Audi.

I think we need to hear it one more time Frank.

Post by **racer12306** » Wed Feb 10, 2010 12:30 pm

JEFF DRIVES AN AUDI

Post by **occasional demons** » Wed Feb 10, 2010 12:35 pm

And just for good measure....

racer12306 wrote:Guys, he has an Audi.

racer12306 wrote:Jeff doesn't have a Neon.

He has an Audi.

racer12306 wrote:JEFF DRIVES AN AUDI

Donkeypuncher · Post by **Donkeypuncher** » Wed Feb 10, 2010 1:07 pm

The camaro/firebird muffler is 2.5" inlet with 2x 2.25" outlet, but I guess that only works if you want dual outlets. As long as you use the 5x8 style muffler, they have anywhere from 2.25" up to 3" inlet mufflers.

Post by **racer12306** » Wed Feb 10, 2010 1:10 pm

neonslg09 · Post by **neonslg09** » Wed Feb 10, 2010 1:12 pm

Donkeypuncher wrote:The camaro/firebird muffler is 2.5" inlet with 2x 2.25" outlet, but I guess that only works if you want dual outlets. As long as you use the 5x8 style muffler, they have anywhere from 2.25" up to 3" inlet mufflers.

OMFG

Did you respond on purposed? If you didn't, your 2gn's royal dumbass.

JeffM · Post by **JeffM** » Wed Feb 10, 2010 1:12 pm

I guess having a signature with my Audi in it doesn't make it obvious enough.

Thanks to everyone who tried. I figured I'd ask here, instead of over on the Audi forums, because people here know a lot more about cars than most Audi people.

OB · Post by OB » Wed Feb 10, 2010 7:07 pm

Not to be a dick, but I'm gonna recommend that you keep the tech questions over on the Audi boards. People are going to get way too confused over here (yes, including myself).

This should technically be in OT, since it isn't Neon related. I'll leave it for now though, since most of the info/replies ARE neon related lol.

blueneo03 · Post by **blueneo03** » Wed Feb 10, 2010 11:02 pm

what a4 do u have? my buddy had a 1.8t and the exhaust was like 1.5 inches so i think anything would be an improvement over the stock. even with a 1/4 inch bottleneck i don't think it would hurt it too much if ur gaining that much diameter.

Donkeypuncher · Post by **Donkeypuncher** » Thu Feb 11, 2010 2:16 am

neonslg09 wrote:
Did you respond on purposed? If you didn't, your 2gn's royal dumbass.

I answered the question that he asked, which was about magnaflow not having a 2.5" muffler, which they actually do have one. Don't be a douchebag. We know he has an audi, and I answered his question.

Also, learn how to spell.

Mat00ES · Post by **Mat00ES** » Thu Feb 11, 2010 7:34 am

I thought you got rid of your neon?

JeffM · Post by **JeffM** » Thu Feb 11, 2010 9:23 am

blueneo03 wrote:what a4 do u have? my buddy had a 1.8t and the exhaust was like 1.5 inches so i think anything would be an improvement over the stock. even with a 1/4 inch bottleneck i don't think it would hurt it too much if ur gaining that much diameter.

I have the 3.0L. I know for a fact that there is a bottle-neck in the stock resonators that bring it down to something like 1.5 or less. So anything over that would be a great improvement. Thanks for the input.

Donkeypuncher wrote:I answered the question that he asked, which was about magnaflow not having a 2.5" muffler, which they actually do have one. Don't be a douchebag. We know he has an audi, and I answered his question.

Also, learn how to spell.

Don't worry, I caught what you were saying. I'd rather not buy just a tipless muffler but, if it comes to that, I might have to. Thanks,

Mat00ES wrote:I thought you got rid of your neon?

He Hate Me · Post by **He Hate Me** » Thu Feb 11, 2010 9:51 am

Orrrrr I have a QTP electronic cutout that you can weld in to your exhaust (somewhere of your choice), preferbly right after the cat, than you can open it when you want

I orginally bought it for my Passat, but I'm selling that. It's brand new. $150. I paid over $220. Comes with a switch, wiring, y pipe, and the electronic cutout

It's for 2.25" piping, which I believe yours is, because as we know, Passats and A4's are essentially the same cars as we both know

B5s.

neonslg09 · Post by **neonslg09** » Thu Feb 11, 2010 3:21 pm

Eye-i kant wealy spill two weall.