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E30 to E46 Muffler conversion. 85 318i

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    E30 to E46 Muffler conversion. 85 318i

    I recently received a few questions on an exhaust project I had planned, and since my bavauto header arrived a few days ago, I thought I would document the process.

    I am restoring an 85 318i, along with some misc. custom work; much of which has yet to be done. At this point, I have worked most of the kinks out of a horribly abused engine. (included wrong oil used for years) The Exhaust was shot. muffler had holes / separation, Cat was clogged (O² sensor bad) and the increased backpressure blew out the welds on my downpipe. I paid $500 for the car total.

    SO, I purchased a Bavauto ceramic / sterling coated header ($445), and was lucky to find a beautiful AC Schnitzer muffler for an e46 318, relatively cheap. ($365) I paid around $150 total in shipping for both.

    I knew I would have to move some hangers around, and / or get some custom pipework done. Exhausts shops can usually fit any muffler to any car. Depending on size, and space available, of course. If you aren't relatively proficient with a welder, ask a local exhaust professional, they are usually pretty helpful.

    I used an inner shield MIG welder, so the welds are a little sloppy / splattery, but they work =) not bad for a portable welder with hand tools done in my driveway tho =)

    I DID have to get a piece of midpipe bent by an exhaust shop for me, because I took the opportunity to increase the size to 2". The Header came with a midpipe that reached as far as a stock cat would. (I have no cat... I may put one in later if my O² sensor isn't getting enough heat to function properly) My muffler pipe was about 2' short of where the midpipe ended. Also, the stock pipe had a factory "crush" in it so it wouldn't contact the Rear diff, or drivelines. Instead of having the shop do this, I just had them make the bend closest to the muffler at a slightly different angle, with a slight increase to the bend. note slight... around 1-2°.

    Well enough History, I will end this post and repost with pictures in the next few minutes.

    #2
    OK. First Pic. 100_0145.jpg

    A good Before shot. Stock hangers, heat shield. all needing to be modified.

    100_0154.jpg

    100_0157.jpg

    More Before shots.

    100_0161.jpg

    Header after installation, simple bolt on. I did have to "modify" the heatshield on the Pass side firewall, since it contacted the header. The modification included blunt objects, and a rubber mallet. Note: at this point, I have not mounted the midpipe that accompanied the header.

    100_0166.jpg


    Since 5 pics is the cap, I will make a repost in a couple more mins =)
    Attached Files

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      #3
      Midpipe Hanging from some wire. 100_0178.jpg

      100_0181.jpg

      100_0184.jpg

      You can see the muffler and other midpipe hanging in their relative positions here. Since I have rudimentary tools, and don't install exhausts for a living, and since this is not a bolt on job, I wanted as much layout as possible. Note the tight clearances in the next shot. 100_0189.jpg

      Since I wanted my tip to show, I needed to move the mounts further to the rear of the car. Note that with my current diving board bumper, I cannot move the muffler far enough back. Since I planned on adding a plastic bumper in the very near future; however, I planned for this and moved it roughly far enough back to show the AC Schnitzer logo =) I will fine tune if I need to later.

      Here is a shot on the driver side of the heat shield, where I needed to remove some material.

      100_0193.jpg

      Next 5 coming up in a minute.
      Attached Files
      Last edited by Thames; 08-11-2008, 10:39 PM.

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        #4
        These pics are after I plotted the mounting points for the hangers, and welded them on. I got a few shots from different angles.

        100_0205.jpg
        100_0206.jpg10
        0_0209.jpg

        After the hangers, I replaced all the components on their temp. hanging wires, and tack welded them where they should go. I pulled out the long section, and welded around all the seams. This is the result.

        100_0220.jpg

        Finished product in the next post!
        Attached Files

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          #5
          OK. Finally finished the installation, this is the next day. (today)

          In this pic 100_0226.jpg you can see how I reused the stock hanger, and can also clearly see the increased bend / angle on my shop bent pipe. Yes, this lowers my ground clearance. *shrug* I plan on keeping my stock height, or maybe take a 1" drop... depending on shocks. if I need to later, I can hack it out and replace it... or more likely have an exhaust shop do it =-)

          Final clearance with the spare tire well. Still tight.
          100_0238.jpg

          I meant to get a shot of the opposite hanger, it was even tighter. I may knock in the trunk panel there a bit if I hear it contacting in corners. I may also drill a hole there, and put a rubber plug in; to keep the trunk watertight, and give it more clearance.

          100_0240.jpg

          Nice shot of the end result.

          I wanted to note that the mounting point on the rear tirewell, with the muffler installed, wants to dimple below the hanger mount slightly. The shape prevents it from denting, but this will no doubt lead to increased noise with the metal vibration. I will stiffen the structure below and to the sides of the hanger with some folded sheet metal, possibly as thick as 1/8"; in the near future.

          I also plan to drop the system and the heat shield before I paint, and install some dynamat on the body side, then reinstall everything. I will also do a full dynamatting of the interior, among a long list of other things down the line.

          Also, on another note. Since this is an 85 manufactured in 11/84, it has an 84 O² sensor. These were mounted in the manifold on 84's, and in 12/85 a different O² sensor, mounted in the downpipe (and $80 more) was used. Since the O² senor on the header is mounted in the collector, I may need to change to the later sensor =-(.

          Also, no cat affects O² sensors in a big way, since they need backpressure / temp to function properly. Since the header is ceramic / sterling coated, my temperature / exhaust velocity has been increased... not sure what affect this will have on the sensor... makes for very complex troubleshooting down the line... but oh well.

          Also, for those thinking of doing this... I noticed the header heats up / sheds heat faster. (heat transference) That being said, the engine bay is a bit hotter around the header area... I may install some ducting and 12v 80 / 120mm fans in the near future... only problem is where to port it to. I thought about dumping it out a fender vent... we'll see.

          Anyway, I hope this helps anyone thinking of doing something similar...

          -Thames
          Attached Files

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            #6
            that pipping hangs so low

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              #7
              Great project and write up, show us pics of the tips side shots etc.
              sigpic
              WTB-Strut Bar

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                #8
                So what's under the hood to warrant this exhaust work?
                Mtech1 v8 build thread - https://www.r3vlimited.com/board/sho...d.php?t=413205



                OEM v8 manual chip or dme - https://www.r3vlimited.com/board/sho....php?p=4938827

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                  #9
                  Originally posted by e30s52 View Post
                  that pipping hangs so low
                  Yeah, its a good 2" lower than stock. I may redo it later on, but until then it will work =)

                  Originally posted by Jean View Post
                  So what's under the hood to warrant this exhaust work?
                  Just a lowly m10 =-) I needed a new exhaust system from the manifold back anyway, and this cost a few hundred more than stock, so I figgured what the hell.

                  Also, I intend to gut the interior, drop the engine, do a full repaint, inside and out. Interlagos blue with an 8" lachsilber stripe down each side, with rivets / bolts down the length, and a pinup girl on the fender and / or door =)

                  I will add some e46 heated memory seats up front, or perhaps some heated e36. I will get black interior panels (instead of tan) and make a fiberglass roof panel, and center console. I have also toyed with the idea of an e36 console... we'll see..

                  And painting comes after doing a plastic bumper swap, with an mtech body kit =)

                  Alot of work for an m10, when most people do an engine swap with 318's... This will be my work car though. and since I'm a custom painter, it should reflect my work =) So basically this will be for gas milage, and I will get an e46 m3 for a play car once I finish.. .. .. sometime next year probably.

                  Long answer for a short question I know... aside from the fact that most will think me crazy =S

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