02-11-2020, 10:34 AM | #23 | |
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Also passing emissions specifications isn't that difficult, but it is very expensive and takes time. So having the certification doesn't mean it's higher quality, just that the manufacturer went through the legwork to get it. Generally most won't go for the cert because it has a marginal increase in sales and profits. It also doesn't cover everything. Like in the US, meeting national EPA standards doesn't mean that you meet all emissions laws, especially in states like California. So it all depends on the manufacturer, what they think is worth it and their marketing strategy. It also goes to note that most OEM catalytic converters aren't immediately after the cylinder head/turbo like on BMWs. The more I think about it, the more I'm settling on the fact that it's a design flaw in the exhaust. You don't hear about this on VW, Honda, etc. even with cheaper systems. I know many people with 400+hp Big turbo kits that have aftermarket catalytic converters in place. |
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02-11-2020, 12:06 PM | #25 | |||
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The high quality catted DPs from respected manufacturers maintain the emission standard of the vehicle (e.g. EU6), which is the whole point. Hence each CC is subjected to regular emission tests by authorised facilities. The compliance is achieved and maintained by using higher quality / higher purity materials (i.e. precious metals). This is what drives the cost up, not the simple metal pipe and not the one-time certification. Quote:
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Last edited by Skyhigh; 02-11-2020 at 12:24 PM.. |
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02-16-2020, 01:43 PM | #26 |
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This only happens when you get "clever" and crank the burbles to max.
For those that do not understand what cat's actually do, they get hot and start glowing orange. Their purpose so ignite any unburnt hyro-carbons (aka fuel) so that the exhaust leaving the car is has no unburnt fuel. When you ask for the "burbles" to you sending larger quantities of raw fuel into the cat, it ignites, and you get a pop. If that cat starts to melt (it was never designed for actual combustion), then it you gets this perpetual "hammering" effect from the burbles which would result in what the OP has seen. If it's popping in the cat, pressure will go backwards and hits the turbo, which would technically want to drive it backwards. No different than what happens during pre-ignition inside the cylinder. |
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02-16-2020, 02:25 PM | #27 |
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What you are saying is partially true, but are you saying "no cat, no pops" (since you are saying you need a cat to ignite the unburned fuel)?
Because that is not the case, as we all read around here And what you describe is not exactly how a cat works it is the chemical reaction that improves the exhaust gases, not any combustion that happens in it but yes - it only works efficiently when up to temperature (which is why we have cat pre-heating phase when we start the engine).
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02-18-2020, 06:36 AM | #28 |
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Another one bites the dust.
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12-15-2020, 05:59 AM | #29 |
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I know this is an old thread but I just encountered a very similar cat failure on my N55 M2.
https://f87.bimmerpost.com/forums/sh...0#post27017700 A bit less advanced but very similar looking shape of shrinking. |
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