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Smog Stuff - Long pathway to exhaust

Discussion in 'Technical Q&A' started by 2dinos, Nov 9, 2009.

  1. 2dinos

    2dinos F1 Rookie

    Jan 13, 2007
    2,525
    The old 320 BMW has a fairly long pathway from the exhaust valve to the cat. It appears roughly to be the same as BB's. Also, it has an "old" un-heated O2 sensor and NO Air-Injection-System. Yet somehow, it is CA certified.

    I've noticed most of the CARB door stickers on BBi's do not call for AIS.

    Questions:
    1. How in the world does that cat light fast enough to pass the CA certification test?? Where the cat must start to light in ~20 seconds, and be fully glowing in 70 seconds. This is after sitting 24 hours. This is the CA SMOG reqm't for Boxers. None of this drive around the block hard stuff.

    2. Any folks have a header / catalytic converter wrap they "like"? Ideally great insulation properties that's clean and simple to work with. No fiber lint mess that's hard to handle etc.

    I know this is REAL as I've seen my CO emission go from 12 gr/mile (got a chance) to over 70 gr/mile (no way in h@!!) just by testing on warm afternoon vs a cold morning.


    Thank you for any help.
     
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  3. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    20,295
    Texas
    Full Name:
    Steve Magnusson
    Are you comparing a 2L K-Jet with Lambda BMW 320 to a 5L K-Jet without Lambda 512BBi? Or has the 512BBi also had some sort of Lambda control added?

    One difference is that on a "grams/mile" basis, the BMW 320 will have a ~2.5X advantage just based on the relative displacements.
     
  4. 2dinos

    2dinos F1 Rookie

    Jan 13, 2007
    2,525
    512BBi K-jet with (lambda controls, via freq valve, heated O2s and Bosch lambda ECU) X2


    Ok. That makes perfect sense, and initally scared me that the bigger motor is going to have a "smog handicap" of sorts; but, there are many larger displacement (>2liters) engines that pass the 7gr/mi standard. And looking at this from the other direction (small motors), I understand that motorcycles are just as tough with a whole compliment of challenges to pass this standard. That said, it makes sense that generally speaking, the less fuel burned per mile the better.

    I did a kwik calc and came up with 10 mi/gal equates to ~280 gr/mi of fuel and given that after the fun with chemistry you end up with some amount of CO/mi for a given engine efficiency (better would be less CO and more CO2). Anyway, the more fuel it burns to begin with, the more you need to clean up. Is this sort of what you are saying?

    So how have these BBi's passed this test without AIS? I'm looking into header wrap as the way to save the day.


    Thanks for the response.
     
  5. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    20,295
    Texas
    Full Name:
    Steve Magnusson
    I'm not that familiar with the aftermarket ECUs, but I don't think any Lambda system can be up and working within the "20~70 second after cold start-up" test you mentioned. When you talk of "my CO emission go from 12 gr/mile (got a chance) to over 70 gr/mile (no way in h@!!) just by testing on warm afternoon vs a cold morning" is that 70 seconds after a cold start-up or during fully warm engine conditions?

    Yes, but not sure if they adjust the gram/mile limits based on displacement/model to even things out a little bit. On the older "CO percentage/HC PPM" based tests, there was no penalty at all for more displacement (which was maybe a little unfair the other way ;)).

    Are you sure that they have? The CARB might not require an AIS, but might be that you'll never pass those limits without one. Even the later (and much more sophisticated during cold-running) KE-Jet with Lambda TR systems still had an AIS (and I'd wager that the emission limits then were, at worst, the same as you're trying to hit). I have a vague recollection of a Boxer Owner reporting success using an aftermarket electrically-driven air pump.
     
  6. 2dinos

    2dinos F1 Rookie

    Jan 13, 2007
    2,525
    It's a stock Bosch ECU from a BMW 320i. All the testing is done from stone cold. The ECU's do respond easily in that time frame as a function of the heated O2 sensors giving a signal. I've timed the response, and it's about 10 seconds with a newer designed 4-wire NTK sensor.


    It is what it is. There's no grace for size etc.


    I'm not sure- - - But now comes the interesting part - there are 512BBi's that have the CARB sticker without AIS, and even if that seems impossible, then what about the VW rabbits and BMW 320i which has lambda control with an un-heated O2 sensor. and no AIS in place. These machines have a long primaries going from the exhaust valve to the front of the cat brick.
     
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