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Thread: Header / mid / cat advice for my DD

  1. #1
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    Header / mid / cat advice for my DD

    OK, so here's the situation:

    My cats are starting to fail - I've gotten a couple check engine codes for cats below threshold in the last 5 months or so.

    Also, we have an M54 going into the race car in the next 6-9 months, and I'm going to use my stock headers on it (it didn't come with the factory headers and the E36 M3 headers are an easy stock-looking upgrade for the M54).

    So I've planned to get Racelands, but now I need cats too, and everyone seems to plumb the Racelands into a 3" single - which I don't like. I had planned on having a shop weld a 2-bolt flange on the stock midpipe, but now that I need cats I'd just prefer to find a mid section with cats that will bolt up all the way.

    This is not a track car. I have 245k miles and add about 10k every year. I'm not deleting the cats, not getting a track pipe.

    I just want some ideas of midpipes with cats that will bolt up to the Racelands and to the factory muffler.

    If there's nothing out there, I'll stick with my plan and have the cats replaced when I have the flanges welded on the mid pipes.

    -Josh: 1998 S54 E36 M3/4/6 with most of the easy stuff and most of the hard stuff. At least twice. 271k miles. 1994 E32 740il with nothing but some MPars. 93k miles.

  2. #2
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    I think a company or two makes a replacement catted midpipe. Bimmerworld might sell it. Could be made by magnaflo.

  3. #3
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    Header / mid / cat advice for my DD

    DEC produces an after market mid-pipe that contains cats.
    BimmerWorld sells them, as do others.

    The periodic code you are getting could be due to failing Bank 1 and Back 2 O2 sensors.


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    Last edited by bluptgm3; 01-13-2020 at 09:15 AM.

  4. #4
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    RRSperry is offline Senior Moment Member BMW E36 M3 Expert
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    Any competent shop should be able to fab that together, You could even have them use V-band clamps, and a flex pipe section to make it look good too.
    No matter where you go, there you are...

  5. #5
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    Quote Originally Posted by bluptgm3 View Post
    DEC produces an after market mid-pipe that contains cats.
    BimmerWorld sells them, as do others.

    The periodic code you are getting could be due to failing Bank 1 and Back 2 O2 sensors.


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    I have thought about that. And I'm running pretty cool lately, too, since my thermostat is dead but I live in Austin and don't really need a thermostat.

    My rear O2s are new ish, but they may be older than I'm thinking (and maybe I'm mis-remembering and it was the fronts I changed last time. Or maybe it was the Escalade. Maybe I need to go look at my records. Man, getting old here).

    I'm really looking for a bolt-on cat + midpipe solution that will work with the Racelands, though even then it may just be easier to have a local exhaust shop weld it all together. Which would let me delay the cat replacement until I'm sure it's the cats and not the O2s.

    I also remain leery of aftermarket cats that only last a few years, so finding an OE cat on a midpipe that bolts up to the Racelands may leave me with the Euro cat + midpipe, which is cool but far more expensive than just going the fabrication route.
    Last edited by blckstrm; 01-13-2020 at 01:56 PM. Reason: Spelling

    -Josh: 1998 S54 E36 M3/4/6 with most of the easy stuff and most of the hard stuff. At least twice. 271k miles. 1994 E32 740il with nothing but some MPars. 93k miles.

  6. #6
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    Header / mid / cat advice for my DD

    Quote Originally Posted by blckstrm View Post
    I have thought about that. And I'm running pretty cool lately, too, since my thermostat is dead but I live in Austin and don't really need a thermostat.
    An engine that is not at a stable temperature is not going to run correctly, potentially running rich do to under cooling, causing the engine management system to be ineffective in managing fuel properly.

    Quote Originally Posted by blckstrm View Post
    My rear O2s are new ish, but they may be older than I'm thinking (and maybe I'm mis-remembering and it was the fronts I changed last time.
    It was the head pipe/pre-catalytic converter sensors (that I referred to above) causing an over rich condition that causes the post-catalytic converter sensors to report ‘cat’ failing.


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    Last edited by bluptgm3; 01-14-2020 at 09:02 AM.

  7. #7
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    Quote Originally Posted by bluptgm3 View Post
    An engine that is not at a stable temperature is not going to run correctly, potentially running rich do to under cooling, causing the engine management system to be ineffective in managing fuel properly.


    It was the head pipe/pre-catalytic converter sensors (that I referred to above) causing an over rich condition that causes the post-catalytic converter sensors to report ‘cat’ failing.


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    Yeah, all things I've thought about. At my mileage... I tend to wait until something is really dead before replacing it. Running all summer without a cat CEL would pretty much certify it's the running cool that's doing it.

    The only reason I even asked is I need to move forward with the headers and wanted to just take care of everything at once. But without a good midpipe solution it makes a lot more sense to just do the headers, have the midpipe cut and welded, and just wait on everything else.

    Man, I hate letting anyone else work on my car, even if it's just the exhaust.

    -Josh: 1998 S54 E36 M3/4/6 with most of the easy stuff and most of the hard stuff. At least twice. 271k miles. 1994 E32 740il with nothing but some MPars. 93k miles.

  8. #8
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    Quote Originally Posted by blckstrm View Post

    The only reason I even asked is I need to move forward with the headers and wanted to just take care of everything at once. But without a good midpipe solution it makes a lot more sense to just do the headers, have the midpipe cut and welded, and just wait on everything else.

    Man, I hate letting anyone else work on my car, even if it's just the exhaust.
    Get a full SuperSprint set-up...headers, mid-pipe, and cat back exhaust.



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  9. #9
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    Quote Originally Posted by bluptgm3 View Post
    Get a full SuperSprint set-up...headers, mid-pipe, and cat back exhaust.
    That would cost a lot of money. Too much actually in my opinion.

  10. #10
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    You could always do Some shorty headers and then just bolt up a factory midpipe from someone that has them just laying around. I know I've got an extra and I doubt I'm even close to the only one. Just as a data point i've got shorty headers and really like them more than my old racelands. Just my 2 cents

  11. #11
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    This is all good feedback.

    gsanvi - yeah, a bit much for me too. I have no problem spending money on the car, but I'm less excited to spend money when I'm unsure whether I'll be happy I did it. And not that I've haven't spent three to four times what I originally paid for the car on parts over the years, but that whole SS setup would be nearly what I paid for the car all by itself.

    I've had the car ten years now, and have done a lot of work to it - but I just got a strut brace last week. What's been reported at times as dubious benefit completely turned me off, and despite ease of installation and relatively low cost I've just avoided it. I stumbled upon an aluminum Mason race brace for a song on BMW CCA classifieds a couple weeks ago and finally pulled the trigger. And now I'm kicking myself - why did I listen to the people who said it did nothing (or conversely, how bad is my car that it made THAT much difference when other people can't feel any difference)?

    Headers falls in a similar bucket for me, but with the race car needing my stock headers and with a 3.5" intake / injector package coming up in the next year, I'm likely in a place I can actually make use of it. It'll be gain no matter what - this question of which makes the most (Turner shortys or Racelands) - either will do better than stock. The Racelands retain the O2 bungs, the Turners retain the factory midpipe, so I'd be having welding work done either way. The Racelands likely will give a little more top end once cams finally happen vs the Turners, though either will likely give me more than factory headers once the intake/MAF/injector install is completed. And I am very much a do-it-once type of guy. And for the cost of the Turners - that just seems a bit much when I'd likely want to trade them out for some long tubes at some future date.

    I guess that's clarity and a decision made.

    Thanks for the discussion guys!

    -Josh: 1998 S54 E36 M3/4/6 with most of the easy stuff and most of the hard stuff. At least twice. 271k miles. 1994 E32 740il with nothing but some MPars. 93k miles.

  12. #12
    NeilM is offline Member BMW E36 M3 Expert
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    Quote Originally Posted by blckstrm View Post
    Headers falls in a similar bucket for me, but with the race car needing my stock headers and with a 3.5" intake / injector package coming up in the next year, I'm likely in a place I can actually make use of it. It'll be gain no matter what - this question of which makes the most (Turner shortys or Racelands) - either will do better than stock. The Racelands retain the O2 bungs, the Turners retain the factory midpipe, so I'd be having welding work done either way. The Racelands likely will give a little more top end once cams finally happen vs the Turners, though either will likely give me more than factory headers once the intake/MAF/injector install is completed. And I am very much a do-it-once type of guy. And for the cost of the Turners - that just seems a bit much when I'd likely want to trade them out for some long tubes at some future date.
    There's another, practical, consideration when choosing between shorty headers and anything else: the shorties are very difficult to install to the head. I know (experienced) people who prefer to at least partially lift the engine out of the car rather than struggle with access to the studs/nuts. I installed my shorties to the head while it was out of the car for a head gasket job, and even that wasn't as straightforward as you'd think. You won't face that particular problem with the Racelands.

    Neil

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    Quote Originally Posted by NeilM View Post
    There's another, practical, consideration when choosing between shorty headers and anything else: the shorties are very difficult to install to the head. I know (experienced) people who prefer to at least partially lift the engine out of the car rather than struggle with access to the studs/nuts. I installed my shorties to the head while it was out of the car for a head gasket job, and even that wasn't as straightforward as you'd think. You won't face that particular problem with the Racelands.

    Neil
    Thank you - this is a great point. I didn't want to complain too much, but yeah - I've read that shorties are a major pain to install and I'll be happy to avoid that extra layer of trouble. After all, this is still my DD and having it down for a week just to install headers seems a little extreme.

    -Josh: 1998 S54 E36 M3/4/6 with most of the easy stuff and most of the hard stuff. At least twice. 271k miles. 1994 E32 740il with nothing but some MPars. 93k miles.

  14. #14
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    Why not just out the cats and have the exhaust shop weld in a couple 300 cell cats in its place? Definitely the cheapest option.
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  15. #15
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    Quote Originally Posted by blckstrm View Post
    Thank you - this is a great point. I didn't want to complain too much, but yeah - I've read that shorties are a major pain to install and I'll be happy to avoid that extra layer of trouble. After all, this is still my DD and having it down for a week just to install headers seems a little extreme.
    Shorties do suck to put in, no question there. Took me and some small handed helpers about 8 hours to install start to finish while the engine was in the car. With the engine out on a stand is was less than 30 minutes but that's not an option for everyone haha. I was just offering a different solution. They definitely aren't the solution for everyone but they were worth the effort for me. It helps I got a used set off the forums so It wasn't much more than the racelands and allowed me to run stock mid pipes un modified and then go to off the shelf race exhaust solutions. Mine did have the appropriate O2 Bungs as well. Helped with mid-range as well to boot. Good luck with your solution keeping a high mileage daily running properly is a fun project.

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