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07-08-2010, 01:40 AM | #1 |
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Decat the Z4M..
What happens when I decat my Z4M? Any loss hp? More sound? I want more than my Hayward&Scott back boxes...
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07-08-2010, 01:54 AM | #3 |
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07-08-2010, 03:51 PM | #4 |
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The US-spec cars have two pairs of catalytic converters. One in the header section. One in the s-pipe section. Removing the cats in the s-pipe section (aka section 1) results in no warning lights (since there are no sensors in there) and is a good modification. It deepens the exhaust note a bit and probably adds a pair of horses. Nothing major. Removal of the cats from the header section, however, will require you to address some check engine lights since there are O2 sensors before and after.
Not sure how the Euro-spec car is setup, but I believe they only have the cats in the header section and thus removal will cause a check engine light.
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07-08-2010, 04:34 PM | #5 |
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I think you got it backwards... the euro-spec only have the second set of cats with the 02 sensor behind them. This is why euro headers only have 1 o2 sensor bung.
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07-09-2010, 05:02 AM | #6 |
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Thanks for all for your kind comments..
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Z4MC_Black Sapphire/Imola-_-DMS ECU ll H&S cat-back ll H&R coilovers ll CF Lip ll Lamin-X ll Matte black kidneys ll Afe drop in ll Afe intake elbow ll RPi scoop ll LeatherZ imola shift boot ll ZHP knob...
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07-09-2010, 05:22 AM | #7 |
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Do it! Then we can compare sounds, RPI vs H&S with no catalytic converters!
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08-02-2010, 02:33 AM | #8 |
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Are you decat your Z4M?
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08-02-2010, 02:46 AM | #9 |
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Not planning to at the moment. My O2 sensors already failed once and i think they're starting to go again so i dont want to make the situation worse! Do you have any problems with yours?
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08-02-2010, 04:06 AM | #11 |
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Yea i do. I changed them a few months ago and i'm already starting to get sporadic error messages about them... Probably because it's a UK car running on rubbish Cyprus petrol.
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08-02-2010, 04:25 AM | #12 | |
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If you can see north sides petrols you can thanks for your petrol stations.. I buy the petrol from south for my cars... |
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08-02-2010, 08:09 AM | #13 |
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You will increase your emissions drastically for a mere 10-20hp that you won't even feel and a louder exhaust that you can probably achieve through other means.
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08-02-2010, 05:55 PM | #15 |
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Although I do agree you are increasing emissions it is for sure a gain you can feel. When I dynoed my car I put out 306whp and that same day two e46 m3s with only cat back exhausts on them out out only 278-280whp. Thats a soild 26 wheel horsepower gain over a stock s54! You can def feel that! I also still have the secondary cats in place so I am still controlling emissions a bit. Now my question is do you run cats on your e30 m3 race car?
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08-02-2010, 08:07 PM | #16 | |
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However, the extra 5%-10% power bump would actually matter in a race whereas it is very close to meaningless on the street. Like all trade-offs, one has to consider what one is trying to accomplish when considering the costs/benefits. Anyway, we can debate how well you can feel the 5%-10% bump in power. The majority of M owners wouldn't be able to tell in a blind test. The point is, even if you are the kind of person who can feel it, it will be rather subtle and pretty much pointless on the street. And, you wouldn't be increasing emissions by 5%-10% in return. It is way worse than that. Hard to pin that down as it depends on the specifics of the engine and its operation, but we are talking about orders of magnitude worse. Removing the cats is a horrible trade-off for street driving. Not to mention that it is illegal in most states.
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08-03-2010, 12:18 AM | #18 |
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My race car had cats right before the mufflers with 100 cell and my exhaust has always being wrapped to keep the speed flow and enough heat so the cat would work. with high temperature exhaust a 100 cell cat can perform very close to a 200 cell's one in terms of emissions and still give you high performance.
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