S54 ---> Hellrot E36 328I

[TH3 Shifty]

Calculations are great, however they don't take into consideration the over all flow.

All the air in the tube does not flow at the same rate.
Example, look at a river, the center flows faster that the water on the shore, why? Drag, the water slows down due to the shore, sand, rocks.

Likewise in a exhaust tube, the air against the sides flows slower do to drag, causing a loss in velocity. the game is how to tune to exhaust size to reach terminal velocity. Over sizing can also have a negative effect where the gasss loose velocity and slow down do to too large an area that the air can not maintain a straighter path.. and air molecules start to wander and bang around.

since I switched to the euro exhaust system 60mm OD (which is actually 2.25 ID) my car picked up a lot of speed and power post 3500rpm

so so what I'm saying in short, calculations are great but real world testing proves slightly different in some cases

[PITT M3 RR]

I broke down and ordered SEC 1 from an E46 M3... $100, stainless and perfect fit. Looking for a sec 2 option at the moment.

Yiu guys are right, I don't know enough to make the time and effort effective. For Time / $ and return - this is best. Read even MORE and the oem stuff is pretty efficient apparently. I think gpeterson mentioned that earlier. One I have these, a nice short run a muffler and out the back can be fabricated. It'll save me a ton of time, and I can sell off the stromung.

Plus us I have this laying around!! 2.5" all around

[Bimmerman535i]

I broke down and ordered SEC 1 from an E46 M3... $100, stainless and perfect fit. Looking for a sec 2 option at the moment.

Yiu guys are right, I don't know enough to make the time and effort effective. For Time / $ and return - this is best. Read even MORE and the oem stuff is pretty efficient apparently. I think gpeterson mentioned that earlier. One I have these, a nice short run a muffler and out the back can be fabricated. It'll save me a ton of time, and I can sell off the stromung.

Plus us I have this laying around!! 2.5" all around

Not to belabor the point....

don't go dual 2.5 unless you are planning on doing ALL the bolt ons. I.e, airbox, cams, SS V1 or Epic headers. Othewise, the E46 M3 stock 60mm pipe is more than enough. If you're not tracking or racing extensively, stick with the stock diameter size. The gains from dual 2.5 don't show up unless you are moving an astonishingly large amount of air through the engine.

If you are going to be racing exclusively, just get the BimmerWorld 3.5" exhaust/tinnitus-er and pair it with SS or Epic headers. Don't do this on a street car unless you hate torque and hate your hearing.

point is...the S54 is extremely picky on exhaust, specifically on merge location. It can make crazy power with a free flowing exhaust, but to do so without gutting your torque is not a simple task. Stick with 60mm or thereabouts for now and follow the OE piping and crossovers. You can use stock Section 1 (or euro cats!) and stock section 2, then merge the sec2 with your choice of muffler...just don't do it crappily like I did.

[PITT M3 RR]

Ok cool. Here's what I'm doing

us headers > E46M sec 1 > E46M sec 2 > custom dual 2.5 muffler.

Will that work or should I do the oem size for a muffler too!? Damn confusing!!

oh and I like torque haha I have a 3:91 rear end

[FastAlpine]

I've got oem us headers, section 1, and section 2 if you're interested

[TH3 Shifty]

Eventually I'm going to the euro system, headers, section 2 and whatever I can build for section 3. The euro headers and section 2 apparently are worth 25-30hp over the US. It to get the engine in and running, I will using my US headers.

[PITT M3 RR]

Fast, PM'd

shifty - I heard that about. I have emission deleted so technically I could run headers and US sec 1, but I don't mind the cleaner emission. I had headers ordered, but the guy flaked and left me to use the ones I had.

[=BA=]

I used E46 M3 headers, but we modified the flanges on a SS E36 M3 decat section and put it on a stock E36 M3 muffler (euro E36 M3 exhaust system)

Seems to work just fine.

[Harvington]

You may not be looking for advice but just don't over think it. To those reading up and thinking for their future: The stock setup is good - the crossover is in the right spot and if you use stock piece you get yourself in a really good direction.

I used a set of Agency Power headers -> section 1 with two resonators welded in -> stock section 3 -> magnaflow 2-1 - no cats.

Sounds wonderful. No rasp. Decently loud, actually. I don't need to comply with emissions so it makes it all even more simple.

I have not seen a dyno just yet to see if I'm losing out but it's effective and CHEAP! You can find section 1 & 2 for free if you look or poke someone who you know that just got something fancy.

[PITT M3 RR]

Yup any advice welcome.

E46M Sec 1 and 2 on the way for use with US headers. I'll post my diy solution for SEC 3. With time etc...this is the easiest option...ship to door and install. It's a prooven system.

Guess the stromung is going up FS!! Sad day haha

[SneauxM3]

I have my kromerkraft stepped headers that merge into a 3" oval.

Plan is to size it down just a bit more as well, as I'm still curious to see how my output goes running 12.5:1 with E85. Just seems so mixed reading on conversions to single run exhaust compared to dual pipes.

Mr. Stickly, who made the KK headers...felt I would be just fine when emailed my parameters like a year or 2 ago now when planned this out.

[PITT M3 RR]

Sec 1 in today, sec 2 Friday - can't wait! I'm getting very anxious as I look for wheels and tires. Most likely 18X9.5 Et35 with a 245/35...the height should make the 3:91 alittle more friendly on the freeway. I don't see torque being an issue.

So those kromerkraft headers...apparently they're amazing. Maybe one day. Are you running cats in sec1? Or none? I'd like to have something because odor etc...

anyway, all I've read was single for weight, track and ease. Dual for street, sound and low end torque. You read the same?

[Bjazzy2]

You have a very nice build in progress; I recently completed the S54 swap in a e36 convertible. My build is probably 90% the same as yours with a few variants. I am running euro headers with Status Gruppe "rasp eliminator" pipe for section 1, and the front of section 2 merged to my muffler section. I to am running a Stromung muffler but will go back to my Corsa RSC36 muffler once my euro cats arrive. I live in Maryland and still must be emission legal for the next few years.
Guess my Stromung will be up for sale with yours...lol

[SneauxM3]

Exactly. Which my car will definitely be more street/DD use, so we've discuss changing the merge pipe to do dual 2.25"

I never thought I'd spend the money on a set until one of the guys on here who races, was swapping an S62 I think...had 2 sets of 288/280 cams brand new, and used KK headers that would now be of no use to him. I've never seen used prices even get close to the deal he gave me.

Im still trying to decide on the rest of exhaust. No hate, but in high school I originally built my Honda turbo, tossed the cat and did dual resonators to keep from that horrendous rasp sound of straight pipes. Everybody thought it was catted still, and it just smelled like trailing a turbo vehicle. Plus, my M is registered in southern CO as a "farm vehicle," so emissions are of no worry to me thankfully.

[PITT M3 RR]

Finally got a day to get over there.

Bolted up sec 1 and 2 and dropped the car. Pulled out and turned around fine. Ran / idled for an hour+. Temp perfect, no leaks and aux fan worked at it should. New shifter detents are AWESOME!!!!!

I mated that dual 2.5 OBX muffler right to sec 2 so it's all one piece. That required removing the rear most bracketry from sec 2, expanding the gap, trimming that piping AND the muffler. I also had to remove the middle hanger and will need to fab one at the E36 location. All in all, very happy with how it turned out. All I need is to make the rear and middle hangers tomorrow and to find 2 nice tips to have showing out the rear.

The stromung is 19" long in the body with 17" of "muffler". This OBX is 17" of "muffler" 22" over all length...I took it down to about 20.25". I could have gone with a shorter muffler, but I dont think that'd have been enough to dampen the S54...I actually think this may even be under sized, but we'll see. I haven't started it with the muffler on, it was late. I really don't want a roaring exhaust ALL the time. Open sec two was nasty loud haha cool for today.

Don't mind the unfinished-ness of the motor area, after the electric fan I'm securing the coolant hose and anything loose / hanging around. Upper right wiring is still needing run to the cluster. I'm still on the E36 unit for now.

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[PITT M3 RR]

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[PITT M3 RR]

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[TH3 Shifty]

We nice job

[PITT M3 RR]

Thanks bud,

today grabbed stainless steel tips from autoxone and cut them down make a perfect fit. Hangers are custom, mild steel. Welds covered with ceramic 1200 degree + paint and then high temp RTV on top. No rust here. Anything exposed is Stainless. 2 donut gaskets picked up as well and installed on headers to sec 1. All I need is the middle 3 bolt gaskets for sec 1 to 2.

Fitment came out GREAT! I staggered the tips to follow the valence curve. For a minute I though of quad tips like the E46 but I'm happy I did not. Upon starting I found the the muffler has done its job! The car has a low rumble now, very quiet compared to the open sec 2

vid isn't great, it's picking up engine noise and the leak at sec 1/2. Near the end you can get a small sense of the low tone.


before muffler


the good stuff...

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.z

[PITT M3 RR]

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[squashman702]

What's the model number of the muffler? May look in to something like that for my LS1 swap.

Also, why the RTV on the exhaust? The paint should be more than enough, could also use stainless wire to weld with if you're that worried about rust.

[PITT M3 RR]

I can post the exact model once I get to the garage again. It's still on the packing there. About the RTV, just one more level of protection I guess: it's temp rated so what the hell.

edit. Stainless wire for a gasless mig? Is that really a thing? I need to look into that

[squashman702]

I can post the exact model once I get to the garage again. It's still on the packing there. About the RTV, just one more level of protection I guess: it's temp rated so what the hell.

edit. Stainless wire for a gasless mig? Is that really a thing? I need to look into that

I'd be worried the RTV would actually seal moisture against the welds if it started to lift for whatever reason, or there were any sort of holes in it.

I didn't realize you had a flux core only welder, not sure stainless wire exists in a flux core application, guessing it doesn't.

[SneauxM3]

Looking real good

[PITT M3 RR]

Thanks man, very happy with it.

Forgot to add, under the E36 there's 3 mounting points for the muffler hangers. On the driver side are 2 of the sets, one unused. I moved the mount to the normally unused inner one to make this work. If you crawl under you can see what I mean. Maybe different points for different levels of trim?