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    Over heating cats?

    I run OEM headers and cats at the track. Can they overheat and get the ECU to cut power?

    thanks!

    #2
    I ran that for about 5 years in the Midwest where we saw track days in the mid to upper 80’s frequently. If the ECU ever reduced power I did not notice nor were any messages reported from the ECU when scanning.


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      #3
      I'd say that's rare. I run catless headers and section 1 in Texas and I run in 100 deg weather with no power cut.
      2018 Grigio Telesto F80 M3 DCT | :: Bone Stock ::
      2004 Titanium Silver E46 M3 6 Speed | :: Track Car ::

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        #4
        Yes.

        The ECU adds extra fuel when it detects the cats are getting hot enough to damage them, which does cool them-- and hurts power. No codes/errors are thrown. If you can feel it... depends on the person.

        They also don't hold up super well to lots of track use. My stock cats failed at 70,000 miles, almost certainly due to track use (as the powertrain of the car was 100% stock, including tune). Happily they were covered under the factory emissions warranty.

        2005 IR/IR M3 Coupe
        2001 LMB/Black M5 Sedan
        2017 i3 Hatchback
        2008 Black/Black M5 Sedan

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          #5
          I had the stock cats for awhile. I would recommend headers or removing the secondary cats for a track car

          The catalyst was coming apart to the point you couldn’t stand behind the car because it would shoot out pieces of the cat.

          If I had secondary cats I’d probably have a blockage which may cause more serious issues.


          Sent from my iPhone using Tapatalk

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            #6
            There also are actual race cats, that can take the heat. I’ve put 10,000+ track miles on my SuperSprint HJS’s and they’re still totally fine. Plus putting them in section 1 should mean they run a little cooler.

            related: I asked an engineer at HJS what temperature I should set the ecu’s cat protection enrichment to, and he said with their cats it was better to disable it completely.

            2005 IR/IR M3 Coupe
            2001 LMB/Black M5 Sedan
            2017 i3 Hatchback
            2008 Black/Black M5 Sedan

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              #7
              Originally posted by Obioban View Post
              There also are actual race cats, that can take the heat. I’ve put 10,000+ track miles on my SuperSprint HJS’s and they’re still totally fine. Plus putting them in section 1 should mean they run a little cooler.

              related: I asked an engineer at HJS what temperature I should set the ecu’s cat protection enrichment to, and he said with their cats it was better to disable it completely.
              Sorry to resurrect this one, but after recently coming across the topic of disabling enrichment as it relates to the HJS cats on my SSV1 system I'm going to install, I want to make sure I'm doing things properly so as not to damage the cats and/or get codes. My car is 100% stock currently (no coding/tuning) and will get the full SSV1 race system with catted Sec1, all new O2s and EGT sensor. Per Supersprint website, the HJS cats are 100CPI but other posts suggest actually 200? Further research suggests to keep the SAP system in place with these as well, really only deleting SAP if running cat-less.

              Thank you!

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                #8
                The SAP introduces fresh air into the exhaust during cold starts. This speeds up the exothermic reaction in the cats resulting in lower emissions and hence less smell. It is designed around the stock cats and their location but likely still offers some benefit with aftermarket cats. It is not intended to protect the cats in any way and is only used on cold starts.

                During extended high load operation, the system will run richer, which results in lower exhaust gas temps. This is done to control the temps of the exhaust components, including the cats, to keep them within their design limits. Backpressure in the exhaust also contributes to higher exhaust temps. Using higher flow cats and placing them further from the heat source are both directionally correct for reducing temps of the cats. With that being said, understand that you don’t stand to gain much by eliminating the enrichment.

                There is only an approximately 3-5% different in power on most engines between the lambda (~.9) that provides optimum power and the lambda (~.7) which is as rich as you can possibly go without misfiring. I would probably suggest to set it up to still provide a bit of enrichment. Somewhere in the range of .8 to .85 lambda will barely impact power and will still provide some cooling.

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