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  1. #1
    Join Date
    Feb 2014
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    Boosted and Legally catless

    This thread is for entertainment purposes only we do not condone removal of emission control equipment.

    With the disclaimer out of the way, I was recently thinking about the common problem many boosted cars have of blowing out the cats especially once the boost pressure is increased. This has even occurred on some NA cars so this thread will also apply if you are thinking about meeting emissions and wanting a big camshaft in your NA car.

    It's all too common to have cat failures even aftermarket 100-200cell cats, reason being; fueling, tune, heat, HP, pressure whatever the reason boosted cars and cats can be problematic.

    This happens:



    It's all too common where you read about guys blowing them out and then removing them entirely, or swapping to 100-200cells blowing them out eventually and then removing them entirely.

    Now when you remove the cats the car stinks, it's highly obvious as you can smell it.

    A possible solution:
    Which "could" work is installing an exhaust cutout in the straight pipe section of the exhaust and just before the cut out a diversion pipe which goes through a factory/aftermarket cat and then back into the exhaust after the exhaust cutout.

    You could even wire this up to, boost pressure control, TPS or RPM control or even a simple on/off switch.

    Whenever you are cruising or need/wanting to meet emissions shut the cutout all of exhaust gases will then go through the cats and then when needed open the cutout and you will have a straight through exhaust again.

    Emissions testing:
    4/5 gas analyzers that the EPA, RMS etc use are usually on a controlled dyno where rpm generally doesn't exceed 1500-2500rpm so you could "possibly" pass the test if the cats are in the right location to work correctly and is the appropriate cat....obviously also with a camshaft that would be more favorable to meeting emissions.

    I have heard of some heavily boosted cars or cars with big naturally aspirated camshafts in the past running multiple sets of cats and getting cars past on emissions tests for engineering purposes and then removing them after passing the test and going catless again so this could certainly be a possible way of doing that, whilst also giving you the confidence of not blowing the cats out with high levels of boost/heat etc.


    How is this legal?
    It could be very possible to have a very high powered car that meets emission requirements think of it like the bimodal exhaust systems they meet noise decibel meter testing which is at 3 meters 45 degree angle at 3500rpm or whatever it is and then at 4000rpm boom the bimodal opens and it's loud HSV and Holden do it so do other car manufacturers it's 100% legal and they are passing the requirements of the testing parameters, this is very similar to that but based on exhaust gasses, as long as you meet the testing requirements and the car meets emissions standards it could pass.


    How to test if it works:
    RMS and other places do provide free and some paid emissions testing and it is anonymous, so if you do something like this and want to see if you pass you can get it checked over and if you fail you wont get your name or rego recorded etc, they do this as they view it as you trying to meet the test and then go away and further alter the vehicle to pass the test....which you can and probably will do if you try this.

    Summary:
    This was just something that I was thinking about and thought might help some of you guys out who are considering your options when cranking up the boost pressure or throwing a big camshaft into your naturally aspirated car. I google searched to see if it had been thought of or discussed before but seems nobody has thought of it, or those doing it are not talking about it.

    Either way I think it's a good way to try and meet emissions testing which makes the car 100% legal when you pass the testing.

    2014 HSV GenF-GTS fitted with a Forced Induction Interchiller
    http://www.facebook.com/ForcedInductionInterchillers
    Australia's outright Fastest VF GTS & Fastest 6.2L 1900LSA with a stock bottom end
    9.700 @145.22mph 21/June/2017
    V-Box Results 0-100km/h in 2.47sec

    Looking for colder IAT's? we have achieved 11c IAT2 on a 41c day and -8c during winter.
    We have proven cabin AC vent temps are better than GM spec, both IAT2's and vent temps are all on video with nothing to hide.

  2. #2
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    Jan 2004
    Location
    Perth, WA
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    So you hypothetically rock up to a 5 gas test for whatever reason and you think at no stage during the process (engineering approval would be most likely) is the engineer going to look under the car at the exhaust system?

    It won't get engineered so it could only be a temporary thing...may as well put 100cpi's or straight pipe in as either option would have to be removed if you get defected.

  3. #3
    Join Date
    Feb 2014
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    Quote Originally Posted by white_lie View Post
    So you hypothetically rock up to a 5 gas test for whatever reason and you think at no stage during the process (engineering approval would be most likely) is the engineer going to look under the car at the exhaust system?
    As said a bimodal exhaust is exactly the same isn't it?
    If a bi-modal exhaust is open during testing in the rpm range of that test then it will fail the test for noise testing. The same applies here to exhaust gases.

    Hell who is to say the likes of Bugatti, Lamborghini, Ferrari dont already do something like this, especially the veyron they pump out loads of exhaust heat but the emissions testing is at xxxx-rpm as long as you pass that you are fine.

    A veyron could very well be catless and it's controlled in the tune to open up above 3000rpm or x psi of boost.

    Quote Originally Posted by white_lie View Post
    It won't get engineered so it could only be a temporary thing...may as well put 100cpi's or straight pipe in as either option would have to be removed if you get defected.
    There is also no law saying that you cannot do this, and you are meeting/passing the testing requirements if it is setup correctly. If you meet the parameters of the test eg say you have it hooked up to only operate above the testing rpm's then an engineer cannot fail it as you have successfully meet the requirements of the tests.

    If you further wanted 100 cell cats on the straight section you still could have that too.
    Last edited by GenF-GTS; 23-11-2016 at 11:53 PM.

    2014 HSV GenF-GTS fitted with a Forced Induction Interchiller
    http://www.facebook.com/ForcedInductionInterchillers
    Australia's outright Fastest VF GTS & Fastest 6.2L 1900LSA with a stock bottom end
    9.700 @145.22mph 21/June/2017
    V-Box Results 0-100km/h in 2.47sec

    Looking for colder IAT's? we have achieved 11c IAT2 on a 41c day and -8c during winter.
    We have proven cabin AC vent temps are better than GM spec, both IAT2's and vent temps are all on video with nothing to hide.

  4. #4
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    Jun 2013
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    Sth West Syd ��
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    Spot on with Bugatti, they are owned by VW so something dodgy with emissions guaranteed

  5. #5
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    Jan 2004
    Location
    Perth, WA
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    The Euro3/4/5/whatever test that a manufacturer has to undergo is completely different to a simple 5 gas test. They would have to meet the standard urban driving requirements, heavy accelerration, cold start etc etc
    I believe most of the testing is based on achieving a desired speed rather than engine RPM.

    You'd be looking at similar results to the VW 'scandal' if you rigged up such a system...its that simple for them to fudge it thru the ECU, why would a manufacturer bother with a mechanical contraption that draws so much attention?

    They even tried bringing in IM240 testing in WA a few years back until too many cars failed

  6. #6
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    Feb 2014
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    4,491
    900-1000hp in these Supercars will generate a lot of heat and you're saying they have cats that can withstand that heat yet we can have a 500-600hp car that can chew through cats like breakfast cereal and there really has been no proven cat that we all look to and use?

    An example would be name any car making big HP similar to these Supercars that meets emissions.
    If these many Supercars had a special cat that worked it would be available and copied for the aftermarket.

    2014 HSV GenF-GTS fitted with a Forced Induction Interchiller
    http://www.facebook.com/ForcedInductionInterchillers
    Australia's outright Fastest VF GTS & Fastest 6.2L 1900LSA with a stock bottom end
    9.700 @145.22mph 21/June/2017
    V-Box Results 0-100km/h in 2.47sec

    Looking for colder IAT's? we have achieved 11c IAT2 on a 41c day and -8c during winter.
    We have proven cabin AC vent temps are better than GM spec, both IAT2's and vent temps are all on video with nothing to hide.

  7. #7
    Join Date
    Mar 2011
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    VIC
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    my metal cats are still looking brand new after 2+ years of boost alot of wot runs and even some issues with lean events, the exit of the cats go into a angle and that is always white from the heat paint just wont last on it so they do get damn hot

  8. #8
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    Jan 2004
    Location
    Perth, WA
    Posts
    6,752
    I don't think its heat that kills them. They don't work if they're not hot.

    How many hours/days/weeks go in to fine tuning a supercar engine to not only perform but meet worldwide emission requirements? Then how long goes in to tuning the average modified car with little to no regard for emissions?

    My cats are also fine, sure I'm not running crazy power but its been boosted for a few years, numerous runs on the dyno, track etc....seen plenty of cars blow them out in a month or two.

  9. #9
    Join Date
    Feb 2014
    Posts
    4,491
    But white lie and 07GTS your cats are not meeting emissions are they?
    If you got tested you would fail.

    2014 HSV GenF-GTS fitted with a Forced Induction Interchiller
    http://www.facebook.com/ForcedInductionInterchillers
    Australia's outright Fastest VF GTS & Fastest 6.2L 1900LSA with a stock bottom end
    9.700 @145.22mph 21/June/2017
    V-Box Results 0-100km/h in 2.47sec

    Looking for colder IAT's? we have achieved 11c IAT2 on a 41c day and -8c during winter.
    We have proven cabin AC vent temps are better than GM spec, both IAT2's and vent temps are all on video with nothing to hide.

  10. #10
    Join Date
    Mar 2011
    Location
    VIC
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    mine are i think 200 cell cats not sure if they would pass or not but here in vic i think it's a bit easier hope i don't have to find out, also E85 will prob help with emissions so it may even out







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