rebuilding head with bigger cam. will i pass emissions test?

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  • cgk_iii
    Mod Crazy
    • Dec 2012
    • 616
    #1

    rebuilding head with bigger cam. will i pass emissions test?

    rebuilding my head right now and trying to decide on what cam to go with that will still keep me street legal. i did a little research and was thinking of going with the schrick 284/272 cam.

    I have custom headers/exhaust, adjustable cam gear, new rockers, and valve springs.

    Would messing with the cam gear and getting a performance chip and a tune help me with passing emissions? i dont wanna give up just yet so any suggestions would be greatly appreciated
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    • cgk_iii
      Mod Crazy
      • Dec 2012
      • 616
      #2
      *im trying to pass smog in California by the way*
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        • nando
          Moderator
          • Nov 2003
          • 34827
          #3
          284/272 is pushing it. You might have a chance using a stock e30 cat, stock dme and a 900rpm idle, with a fresh o2, no vac leaks, calibrated tps and functional afm.

          Cam gear wont help as you cant adjust overlap, and thats what will cause high hc's. Its also what makes more power...

          A 272 is definitely safer. You might find out what cams, if any, are known to pass.
          Build thread

          Bimmerlabs

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            • cgk_iii
              Mod Crazy
              • Dec 2012
              • 616
              #4
              Originally posted by nando
              284/272 is pushing it. You might have a chance using a stock e30 cat, stock dme and a 900rpm idle, with a fresh o2, no vac leaks, calibrated tps and functional afm.

              Cam gear wont help as you cant adjust overlap, and thats what will cause high hc's. Its also what makes more power...

              A 272 is definitely safer. You might find out what cams, if any, are known to pass.
              How would the stock dme work out with a hotter cam tho will it adjust? I replaced all hoses (vacuum/coolant) and still have stock cat. I read that the 272 camshaft is about the same as the stock cam anyways so whats the difference between the two? I want POWER but i also would love to cruise the streets.. Anyways wish me luck i guess..
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                • bmwman91
                  No R3VLimiter
                  • Oct 2004
                  • 3128
                  #5
                  You cannot legally install an OEM E30 cat in CA anymore. It has to be a certified CA-legal one.

                  A fresh cat and a proper dyno tune should be ok. Hot cams can increase NOx emissions which definitely requires a fully functioning 3-way cat to handle.

                  Transaction Feedback: LINK

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                    • MR 325
                      Moderator
                      • Oct 2003
                      • 37824
                      #6
                      Originally posted by bmwman91
                      You cannot legally install an OEM E30 cat in CA anymore. It has to be a certified CA-legal one.

                      A fresh cat and a proper dyno tune should be ok. Hot cams can increase NOx emissions which definitely requires a fully functioning 3-way cat to handle.
                      You can use an original E30 cat though, that's not an issue. Regardless of that no smog shop would know WHEN a cat was installed if it were aftermarket. It could have been done before the new laws. I have seen E30s do a better job at passing smog with a stock cat from 1989 than a brand new replacement.
                      BimmerHeads
                      Classic BMW Specialists
                      Santa Clarita, CA
                      www.BimmerHeads.com

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                        • bmwman91
                          No R3VLimiter
                          • Oct 2004
                          • 3128
                          #7
                          Originally posted by MR 325
                          You can use an original E30 cat though, that's not an issue. Regardless of that no smog shop would know WHEN a cat was installed if it were aftermarket. It could have been done before the new laws. I have seen E30s do a better job at passing smog with a stock cat from 1989 than a brand new replacement.
                          I'd definitely believe that a stock E30 cat would be better..they have waaaaaay bigger cores than the after market ones.

                          Transaction Feedback: LINK

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                            • reelizmpro
                              R3V OG
                              • Dec 2003
                              • 9437
                              #8
                              Yes, it should pass. Emissions are more about the tuning than anything. As long as it's all dialed in and the cat is good, you should have no problems passing.
                              "I'd probably take the E30 M3 in this case just because I love that little car, and how tanky that inline 6 is." - thecj

                              85 323i M TECH 1 S52 - ALPINEWEISS/SCHWARZE
                              88 M3 - LACHSSILBER/SCHWARZE
                              89 M3 - ALPINEWEISS II/M TECH CLOTH-ALCANTARA
                              91 M TECHNIC CABRIO TURBO - MACAOBLAU/M TECH CLOTH-LEATHER

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                                • cgk_iii
                                  Mod Crazy
                                  • Dec 2012
                                  • 616
                                  #9
                                  Whatever cat i have now passed just fine with everything stock so may as well re use the same cat and hope for the Best.

                                  Anyone know where to go for a good tune in the Bay Area?
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