exhaust options

[mtlbloodshot]

So does anyone know if M52 headers with AKG mounts will cause problems?

[expelled]

Yes sorry!

I am on Revshift mounts and the headers do not hit the subframe. I will try to fit an X-pipe in there for good measure!

[7pilot]

I tried a set of long tube Ebay headers. They sat on the subframe.
There is an earlier post in this thread suggesting that you only have to switch the rear mount of the lower control arms to the compact Treehouse or bimmerworld items.
I can say that it helps to mention what engine mounts you are using and whether you plan to shim the offside of the engine to raise it.
AKG swap mounts appear to be shorter than factory mounts, so expect heavy contact header to subframe.
Adding an xor H pipe aids in cylinder scavenging.
I find that the rasp is more influenced by the type of and number of mufflers used.
My system is rasp free with a S52 extractors into a VSR Twin cat mid section(H pipe) and SuperSprint Tail box.

m

[expelled]

Well I'll be the one to bring this back from the dead.

I'm running the longer ebay headers on my s52 swap.. my plan is to fab up the OBD2 midpipes and the e36 M3 catback..

-How much custom work will I need to do on the front end of the midpipes since these are the long headers?

-Should I still try to fit an X-pipe in there to eliminate rasp or will the stock midpipes and exhaust be enough?

Thanks!

[N2MYE30]

I didnt think that there was need to make a new thread so maybe we can keep some of the exhaust topics here...bump.

This is my current situation. I am going to the exhaust shop soon and wondering how members are mating up their previous exhaust, such as mine below...


...to their 24V manifolds.


I have the e36 downpipe with the o2 sensor already but of course, i have no clearance. I do not plan on getting any sort of headers for this project.

Any members have pix on how they have their exhaust fabed up? BTW, I have a NVM50.

[So Live]

Yeah, basically thats what went down. I had the front 3 feet or so of e34 exhaust. I cut em up and tacked them together and thats what fit.

I guess its fine for a stock M50. but technically the e30 pipes are about 1.75" iirc. just cross sectionally speaking it should flow plenty. dual 1.75 = ~4.8 sq inch. single 3" = 7.07 single 2.5 = 4.9. A few people here were reccomending single 2.25" exhaust for these motors.

Its not my favorite way to go about it. Im sure it could flow a lot better. It is cheap and fairly simple if you can weld. Why not?

[hoveringuy]

So you just modified the e-30 cat to fit the new downpipe?

That's what's what I was wondering about. How do you like it?

[So Live]

Hoveringuy, this is what my set up is but with a e30 325i bb triflo cat back. Seems to work fine.

It was pretty "custom" 4 welds per pipe so 8 total. And yes, I know im a shitty welder. Everything clears with about 1/2 inch clearance everywhere (subframe/sway bar + CAB).

[matt]

It's possible. I wouldn't bother.

Easiest option is probably THR Eyeball Arms and a stock e36 exhaust.

[hoveringuy]

This will be clear to someone that has done the swap but not to me (yet)...

can an m50 manifold and downpipe be used with the stock e30 cat? I am looking at swapping and am looking for the easiest exhaust option until I get it running and can devote the time into a proper exhaust.

What would be involved in mating it?

Steve

[static]

Alright, so the ecu's will compensate enough for a really free flowing exhaust to not harm it right? The loss is just in torque but youd likely gain up top. Can you go too big? Whats an acceptable size for a dual exhaust on a M/S5x motor?

please re-read point #3 in my prev post :) .

yes, you can easily go too big on a NA car. With NA car you need reasonable exhaust gas velocity (and not just for scavenging). With going too big with pipes, the velocity goes down, gases cool off before they exist the exhaust creating a restriction (it's harder to push out cold gases than hot gases due to increased density). Big pipes also create more turbulence, which further harms the flow (laminar vs turbulent flow)
And finally, bigger pipes create drone (which is the sound of "bad" kind of pipe resonance :) ), which i personally hate.

[e30polak]

just think back the the days of the eta.

small intake, small exhaust, tons of low-range torque.

an eta...and tons of torque

[bimerok]

just think back the the days of the eta.

small intake, small exhaust, tons of low-range torque.

eta had 166lb of torque, which is about ~92.5% less then a ton of torque.:D



Just messing with you :pimp:

[87-325ic]

just think back the the days of the eta.

small intake, small exhaust, tons of low-range torque.

[So Live]

Static, thank you for the information. Thanks matt for enlightening me...

Alright, so the ecu's will compensate enough for a really free flowing exhaust to not harm it right? The loss is just in torque but youd likely gain up top. Can you go too big? Whats an acceptable size for a dual exhaust on a M/S5x motor?