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-   -   Is dual exhaust possible on 1998 323ic? (http://www.bimmerfest.com/forums/showthread.php?t=676417)

agoliver2 02-14-2013 09:12 PM

Is dual exhaust possible on 1998 323ic?
 
HI i recently put a new exhaust on my bmw and i just wanted to know if anyone knew if there was a way that i could duplicate this on the other side. Ive seen some e36s on youtube do it but i looked underneath the car myself and found little room due to the gas tank. But people seem to somehow make it work:dunno: I just wanted to know if anyones done this before i go buy myself another exhaust online! i have a dual ram air setup headers and exhaust so i was looking to make a dual exhaust. Any ideas or suggestions i would greatly appreciate thanks :)

ReillyM3 02-14-2013 09:36 PM

In my opinion the rewards are greatly outnumbered by the drawbacks and needed effort. However, its not my car and "different strokes". To do a dual exit you will need to (just by looking under my car) cut into your spare well, alter or switch rear bumper, have a shop mandrel bend and weld the piping, fabricate hangers and drill holes. I havent done it on an e36 but have on my old porsche... You would be better off doing cams as far as performance but once again its your canvas so paint as you must.

ZeGerman 02-14-2013 10:04 PM

The 328 and M3 have totally dual exhaust until it meets way back at the muffler. Unfortunately, the 323 bottlenecks the exhaust ahead of the catalytic converter and then runs a single pipe all the way back to the muffler. There are actually significant power gains to be had with a 323 if you upgrade to the 328 or M3 midpipe with a 328 or M3 cat-back. That's the route I would recommend for this application. As far as having separate dual mufflers, etc., I wouldn't do that. There really isn't room to do it easily due to the spare tire well and it looks silly almost all of the time when people try to do it. Almost universally looks ghetto rigged.

Hectorml07 02-15-2013 08:48 AM

Dual exhaust belongs in cars that come equipped with it already such as the M5, OR E90 M3. Just by looking at them you can tell deserve dual exhaust! I have seen some e36s with dual exhaust though, just not my cup of tea. It makes me giggle lol. It reminds me of guys that I have seen in their tricked civics with large dual exhaust systems in a little 1.8 four banger sounding terrible to me, but I guess it sounds powerful to them.

All in all its up to you and what you do to your car since you are the owner.

B1MM3R 02-15-2013 08:58 AM

Karl nailed it about the 323 exhaust. If you decide to go the route he stated, I have a 328 catback in great shape for $50 if you want it. And also a straight pipe midsection.

granlund 02-15-2013 11:15 AM

Since the 323 only has one O2 sensor, wouldn't an OBD1 325/M3 midpipe be a better choice?
http://www.realoem.com/bmw/showparts...09&hg=32&fg=30
http://www.realoem.com/bmw/showparts...77&hg=18&fg=10

B1MM3R 02-15-2013 11:20 AM

the straight mid pipe I have is obd1 that comes with the 328i catback.

HakenTT 02-15-2013 12:01 PM

323ic single exhaust is not restrictive for 2.5L engine. It goes down to 2 1/4 inch in front of the converter, after the converter it goes to 2.5 inch wide pipe. 190 horsepower has no problem with 2 inch exhaust pipe.

328i and M3 mid section is worse. Right after converters the two small resonators, the pipe is only 1.5 inch wide inside on each side

hornhospital 02-15-2013 01:01 PM

I'll be damned. He's right (if his pipe size figures are right).

323 exhaust before cat= 3.976 sq. in. cross section
323 exhaust after cat= 4.908 sq. in. cross section
M3/328 exhaust after cat each= 1.767 x 2= 3.534 sq.in. cross section total of two pipes.

ZeGerman 02-15-2013 01:19 PM

There has to be more to it than that. There is no way BMW would use a more restrictive exhaust on the 328 and M3 than on the 323. Virtually everyone (except Hawken) has said that the 328 and M3 exhausts flow much better than the 323 exhaust. Perhaps overall diameter isn't the whole story, and that by having a larger overall diameter in the 323 exhaust, scavenging and velocity is hampered, thereby reducing power. Everyone says that a 328 or M3 exhaust on a 323 is the single best performance modification in terms of gaining power.

If the 323 exhaust was superior, we'd all be putting 323 exhausts on our cars... Besides, if the 323 exhaust is 2.5 from the cat back, and the 328 has two 1.5" pipes, that's a half-inch more total from the cat back compared to the 323. Am I having problems with my maths? The 323 most definitely does not have a nearly 5" single pipe from the cat to the muffler.

hornhospital 02-15-2013 04:49 PM

You figure it up. 2.25"/2 (radius)= 1.125" X 1.125" (squared)= 1.265265 X 3.1416 (pi)= 3.976 sq. in area cross section

2.5"/2 (radius)= 1.25" X 1.25" (squared)=1.5625 X 3.1416 (pi)= 4.90875 sq. in. cross section. (NOT diameter).

1.5/2 (radius)= 0.75" X 0.75" (squared)= 0.5625" X 3.1416 (pi) = 1.76715 sq. in. cross section X 2 (two pipes)= 3.5343 sq. in. cross section total.

I really wonder if that 1.5" twin pipe figure is correct.....

southpark11235 02-15-2013 05:12 PM

5 Attachment(s)
While HakenTT seems to be right about the size of the 323 pipe, the 328 pipe is half an inch bigger than he suggest.

hornhospital 02-15-2013 05:17 PM

The real question is what size are the twin pipes coming out of the cats? Or is that one of them? That makes a HUGE difference. That would make the outlet cross section 6.283 sq. in. total , not 3.543

southpark11235 02-15-2013 05:25 PM

The second picture is the 328 pipe after the cat with no bulge.

hornhospital 02-15-2013 05:27 PM

:thumbup: Then the cross section (and flow rate) are WAY higher on a 328 exhaust pipe set. Thanks!

ZeGerman 02-15-2013 05:31 PM

Yeah, it doesn't make sense. Everybody reports power gains with the 328/M3 mid-pipes and cat backs over the 323 units. Haken is literally the only person I've ever heard say that the 323 exhaust is better. His claim doesn't add up, nor should it. BMW would never put a more restrictive exhaust on their higher performing models.

Also, how is cross section different than area? I'm assuming that the terms are not synonyms, but when I calculated the are using Pi*radius squared, it produced the same numbers as your cross section figures. Sorry for being dense...

EDIT: That makes much more sense! Haken said the 328 pipes were 1.5" each, but those photos are showing that they're much bigger than that. I think he was suggesting that they're double-walled, and that the inner pipe is only 1.5" in diameter, but that's not what we're seeing in the photos.

agoliver2 02-15-2013 05:45 PM

hey guys. I would like to thank you guys for the responses as the threads got many. I guess a dual exhaust setup is really not worth it for the mods that need to be made. I was looking and just don't seem to see the clearance for the full exhaust. My 323i is restricted like crazy. they restricted my whole exhaust system my headers my air box my computer my intake manifold & im sure other crap as well. I've changed my headers and they actually close off the outlet with a little indentation in the headers themselves to restrict air flow. I've changed my headers exhaust and made a dual ram air setup & it does 0-60 in around 5.6 which is the best time I've got so . (and it is an automatic)As for the 328-m3 exhaust swap im not really sure if I can put dual pipes all the way from the headers back to my exhaust. I just have a single cat & no resonator. I don't think it will fit but I guess you don't know until you try. I don't understand why they also detuned my car from the factory. The 325 has the same motor & I believe less restrictive. I believe the 328-m3 exhaust will be much better even though form this thread you guys say its smaller. I just don't know how 2 cats are going to fit under my car. But I could be wrong I don't know if anyone's ever done this before? or even m50 intake manifold swap for more power? and my car is a OBD2 not OBD1 to whoever stated above. thanks

ZeGerman 02-15-2013 06:02 PM

Uh oh....

ZeGerman 02-15-2013 06:10 PM

Quote:

Originally Posted by agoliver2 (Post 7383904)
My 323i is restricted like crazy. they restricted my whole exhaust system my headers my air box my computer my intake manifold & im sure other crap as well.

Oh grasshoppa, you have much to learn. The headers, air box, and intake manifold on your 323 are the same units as found on the M3 and are not restrictive.

Quote:

Originally Posted by agoliver2 (Post 7383904)
I've changed my headers and they actually close off the outlet with a little indentation in the headers themselves to restrict air flow.

:confused:

Quote:

Originally Posted by agoliver2 (Post 7383904)
I've changed my headers exhaust and made a dual ram air setup & it does 0-60 in around 5.6 which is the best time I've got so . (and it is an automatic)

Tell me more... You must have bought yourself a magic E36 323 auto which is somehow as fast as a 240hp M3! Don't ever sell it!

Quote:

Originally Posted by agoliver2 (Post 7383904)
As for the 328-m3 exhaust swap im not really sure if I can put dual pipes all the way from the headers back to my exhaust. I just have a single cat & no resonator. I don't think it will fit but I guess you don't know until you try.

Remember all that talk about mid-pipes above???

Quote:

Originally Posted by agoliver2 (Post 7383904)
I believe the 328-m3 exhaust will be much better even though form this thread you guys say its smaller.

Time to re-read this thread.

Quote:

Originally Posted by agoliver2 (Post 7383904)
I just don't know how 2 cats are going to fit under my car

I have no idea, either. :tsk:

Quote:

Originally Posted by agoliver2 (Post 7383904)
But I could be wrong I don't know if anyone's ever done this before?

Nope, this has never been done. You will be the first.

agoliver2 02-15-2013 06:26 PM

well i have read the thread and i have the 0-60 video to back me up! ITs true it does that to 60 if i can find a way to post the video i will, Regardless from the research that i havre done on my car over the years, ive found all this infomation about it being so restrictive. if you would read online, you will see that it is. I have taken my car apart myself and they must obviouslt be restrictive because once ive changes all the parts off my car it went alot faster. If you do some reseach on the 323i you will see that it is . you were saying that the seperate pipes on the 328 were 1.5 incehes each as well so techenecally smaller than a single pipe on my 323i & i meant having dual pipes back to my exhaust in which you would need to have a cat.

Joe__Sterling 02-15-2013 07:42 PM

did you happen to put a different set of wheels/tires on your car from stock? :angel:

jonesin 02-15-2013 07:58 PM

Quote:

Originally Posted by agoliver2 (Post 7383963)
well i have read the thread and i have the 0-60 video to back me up! ITs true it does that to 60 if i can find a way to post the video i will, Regardless from the research that i havre done on my car over the years, ive found all this infomation about it being so restrictive. if you would read online, you will see that it is. I have taken my car apart myself and they must obviouslt be restrictive because once ive changes all the parts off my car it went alot faster. If you do some reseach on the 323i you will see that it is . you were saying that the seperate pipes on the 328 were 1.5 incehes each as well so techenecally smaller than a single pipe on my 323i & i meant having dual pipes back to my exhaust in which you would need to have a cat.

One person said that, then several other people corrected him. Including one guy who posted pictures showing that the first guy was wrong.


Reading retention fail.

agoliver2 02-15-2013 08:02 PM

no they are stock rims with bridgestone potenza tires. ? :dunno:

jonesin 02-15-2013 08:09 PM

Joe asked so that you'd have the benefit of doubt. With larger circumference tires your speedometer would show a faster speed than you're actually travelling because it would show the speed based on the rotation of smaller circumference stock wheels, which is what your speedometer is calibrated for.

Make sense?

agoliver2 02-15-2013 08:12 PM

yes that would make sense but they are stock i dont understand the doubtfulness of my car i will find a way to put on the video if i can figure out how. stock rims just headers dual ram air custom setup and exhaust. pretty quick i believe for a 2.5. thats why i wanted a dual exhaust but it seems not to be possible with the clearance


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