OEM ///M mufflers gutted

[Kgolf31]

Originally Posted by v3.2mc

76mm is the largest that will fit on the OE mufflers due to the outlets being too close together. i do not want to modify that aspect as that would be a lot of work that i'm not comfortable with doing myself.

i guess i could find tips of different sizes and set it up as an homage to RPI...?

Look into C6 Tips or similar.

Something double-walled would look sexy.

[v3.2mc]

Originally Posted by Kgolf31

Look into C6 Tips or similar.

i haven't been able to find any that are not slash-cut, and i think they only come in single outlet with a Y to the tips...? if you've found some, i'd love to have a link.

[Kgolf31]

Originally Posted by v3.2mc

i haven't been able to find any that are not slash-cut, and i think they only come in single outlet with a Y to the tips...? if you've found some, i'd love to have a link.

I know it's a Y to the tips on the C6.

I'll go searching. What I was thinking was the Rogue IKON tips. I had that system on my E46 and they were awesome.

[v3.2mc]

Originally Posted by Kgolf31

...Rogue IKON tips.

those do look good! i like how long they are. i'll have to add those into my search, but i think i'm still partial to a straight-cut tip.

the other project i'm working on in tandem with this i have doubts about the slash-cut style looking right. i don't want to say too much about it, because i don't know if it's going to work, and i also don't want to be the guy who says "it's absolutely going to happen" and then it doesn't.

i do really like the c6 tips though, so if i can find that style, straight-cut, double-wall, 72-76 mm... that'd do nicely!

[dubsesd]

how about these?



http://www.magnaflow.com/02product/s...=main&id=10760

[v3.2mc]

Originally Posted by dubsesd

how about these?

http://www.magnaflow.com/02product/s...=main&id=10760

i the look of them, but they are 89mm... way too big for the OE outlets.

basically, 76mm = 2.99" is the largest that can possibly fit on this setup. the problem i see with moving the outlets is that both of them have to move equally, else they will not be centered in the stock bumper relief. i've considered a double elbow extension for each outlet, but then most of the tip will stick out from the bumper.

ugh!... choices!

i've also considered the 3.0si tips as they are larger than the ///m's. while the size difference isn't huge, it's still a drastic change in appearance.

[dubsesd]

just dont center the tips on the outlets in the muffler. put them tight together and place them offset to the oulets. those big tips would look awesome

[v3.2mc]

crappy cell pic of the mock-up before welding...

[XMetal]

Are you duplicating RPi's straight through design? It looks like that will be LOUD

[v3.2mc]

Originally Posted by XMetal

Are you duplicating RPi's straight through design? It looks like that will be LOUD

absolutely looking to do a straight-through design. while the RPi's are quite loud, i believe much of that is due to the overall shape of the muffler they use. retaining the OE cans should, in theory, produce a lower and quieter tone with much less drone. we'll see if my thoughts are true once they're back on the car.

[Punko]

Any update on this? Thanks.

[ZStig]

cool idea.

[v3.2mc]

Originally Posted by Punko

Any update on this? Thanks.

the passenger's side is packed and welded. after talking with the guy who did the welding, he had some requests to make the next one easier for him. mainly the 6 spot welds on the "lid" (actually the bottom of the muffler itself). instead of cutting out each individual weld, i'll be cutting long strips that are the length of all three spot welds in a row per inner baffle. using filler strips, he'll then just make two clean and pretty welds instead of surface patching like what was required for the first muffler. so, although the two will have identical innards, the bottoms will look slightly different. i plan on painting the cans black anyway... soooo... whoopdeedoo... no one will ever see it unless they're under the car.

after i get back from holiday traveling i'll be gutting the second muffler. once it's back from the welder's, it'll be time for paint, choosing tips, install, and then finally... testing! some of that schedule may be weather dependant, but rest assured... there is absolutely forward progress on this.

when testing does come, i plan to recreate the tests done for ExhaustFest 2012. i already have the dB meter from good 'ol RadioShack. obviously location and ambient air temp will be different (damn you, Cali, and your perfect weather!), but the rest i hope will be up to par.

- eric

[i2ichal2dZ4M]

update?

[Twisted Six]

Originally Posted by v3.2mc

the passenger's side is packed and welded. after talking with the guy who did the welding, he had some requests to make the next one easier for him. mainly the 6 spot welds on the "lid" (actually the bottom of the muffler itself). instead of cutting out each individual weld, i'll be cutting long strips that are the length of all three spot welds in a row per inner baffle. using filler strips, he'll then just make two clean and pretty welds instead of surface patching like what was required for the first muffler. so, although the two will have identical innards, the bottoms will look slightly different. i plan on painting the cans black anyway... soooo... whoopdeedoo... no one will ever see it unless they're under the car.

after i get back from holiday traveling i'll be gutting the second muffler. once it's back from the welder's, it'll be time for paint, choosing tips, install, and then finally... testing! some of that schedule may be weather dependant, but rest assured... there is absolutely forward progress on this.

when testing does come, i plan to recreate the tests done for ExhaustFest 2012. i already have the dB meter from good 'ol RadioShack. obviously location and ambient air temp will be different (damn you, Cali, and your perfect weather!), but the rest i hope will be up to par.

- eric

Cool, looking forward to your findings. By the way...it was 37* here in Laguna Beach-(SoCal) last night.
However nothing like the sub freeze temps I know all to well from Missouri winters,lol.

[v3.2mc]

yeah... the entire state of Iowa is snowed in after a blizzard today.
I measured 12.5" out in the front yard this morning.

as an update: i have both mufflers welded up. currently searching for paint for them.

[Twisted Six]

Originally Posted by v3.2mc

yeah... the entire state of Iowa is snowed in after a blizzard today.
I measured 12.5" out in the front yard this morning.

as an update: i have both mufflers welded up. currently searching for paint for them.

If your not going to Powder coat them, just get the aerosol BBQ blk. high heat paint and make life easy.

[exdos]

Originally Posted by v3.2mc

I think that your configuration will be very loud because the tips are connected to the inlet pipe.

I've modded lots of Z3MC silencers and about 6 months ago, I modded a pair of silencers on my Z4MC, but I didn't go about it in the same way that you've done.

I opened the silencers from the upper surface so that the surgery couldn't be seen when the silencers are mounted on the car.




I removed all the pipe work in the central section and the "U" bends at both ends of the silencers. I then welded blanking plates over the holes into the end chambers so that the flow of exhaust is now "straight through" in the middle chamber. I welded the windows back to make the silencers leak-proof.








The result of my modding is that the silencers are a bit louder than OEM, particularly at WOT. There is is slight droning at 1700-2000rpm. I did my mod to attempt to improve performance rather than just for loudness.

[XMetal]

Exdos,
Are you saying that you have no piping in the middle section? If so, wouldn't that cause a lot of turbulence and therefore reduce flow? It's not really a "straight through" design if you don't "channel" it.

[exdos]

Originally Posted by XMetal

Exdos,
Are you saying that you have no piping in the middle section? If so, wouldn't that cause a lot of turbulence and therefore reduce flow? It's not really a "straight through" design if you don't "channel" it.

My last photo shows the present internal layout and there is no piping in the middle section. The exhaust gas leaves the inlet pipe in the middle section and it finds its own way to the outlet pipes.

As I said, I've done a lot of silencer modding on the Z3MC and have used an ECU datalogger to monitor the changes that occur from producing various different internal configurations, and I've learned what works and what doesn't by trial and error. This is the first pair of silencers that I've done for the Z4MC, and coupled with air-intake mods on the same car, I've obtained some increase in torque and bhp, as measured by datalogging. Now that I've been able to assess my silencer mod for the Z4MC, I might reopen them and slightly reconfigure them to overcome the slight drone.

Here are the before and after graphs produced from the data recorded with my DashDyno SPD datalogger, see: http://www.auterraweb.com/dashdynoseries.html


Before:



After:

[v3.2mc]

i'm digging that more people are searching their own solutions on this. it'd be cool to see at least one more attempt in a different fashion so there's a good data set to pull from for other forum members.

@exdos - i see where you're going with your build. your drone is absolutely being created by the two parallel surfaces left to create standing waves. if you do open them up again, that's the area to focus on. i chose to remove them entirely exactly for this reason.

@all - another solution i came up with after i had already welded these back up is using the perf. tubing source that the e36 m3 guys use that is longer than the piece already inside the muffler. it'd be installed from the inlet and sent directly to one of the tip outlets. the other outlet would get an elbow with a perf. cap on it. fill the assy back up with the acoustic matting, and bango!... a high-flow muffler with potentially excellent anti-vibrational qualities. the down side to this is that you're buying items for the build, which kind of negates the whole recyling thing i'm going for.

[exdos]

Originally Posted by v3.2mc

@exdos - i see where you're going with your build. your drone is absolutely being created by the two parallel surfaces left to create standing waves. if you do open them up again, that's the area to focus on.

You're right. Since my prime objective is to improve performance, I wanted my first attempt at modding the Z4MC's silencers to be as conservative as possible, yet at the same time, be sufficiently radical to make a measurable difference to performance when monitored with my datalogger. I do all the "surgery" and welding myself, so it's no big deal for me to have to open them up again to fine tune them. Before I did this, I'd never seen the internal layout of the Z4MC's silencers, like you've shown in one of your earlier photographs, so I made my opening "windows" based on my understanding of the construction method used by BMW and thought I'd have sufficient room to work to gut them (which I had). Although you can't see from my photographs, I've actually removed all the tubing at the inlet end, except the inlet pipe into the central chamber, and the "U" bend at the outlet end too, and I've packed those voids with some of the fibreglass material.

I have a very radical mod for the silencers for the Z3MC which works extremely well and with no droning, which is not altogether dissimilar to what I've done in the Z4MC's silencers, so I will probably replicate that if I reopen my silencers.

Originally Posted by v3.2mc

@all -the down side to this is that you're buying items for the build, which kind of negates the whole recyling thing i'm going for.

We're on the same page here: I like analysing the function of the OEM parts and then modifying them at little or no cost.