05-23-2022, 02:54 PM | #1 |
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Hello all - I purchased a '21 M2C which came with an AA non resonated single midpipe. When in sport or sport+ and upshifting, there is that single loud raspy pop during throttle lift in lower (2500-4000) RPM.
(I am not referring to the burbles, I tuned that out with bimmerlink) Any idea how to tone this down? I was thinking about buying the resonated connecting pipes. Does anyone think that might help? Any suggestions otherwise? I didn't want to do any BM3 or ECU tuning and I don't want to drive it in comfort lol! Thanks
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05-23-2022, 06:08 PM | #2 | |
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05-23-2022, 07:37 PM | #6 |
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Yeah that's what I understand but I don't want to go back to stock.. so I am thinking run resonated connecting pipes to the stock muffler from my AA single midpipe
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05-23-2022, 08:46 PM | #7 |
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Is this the brrraaap sound?
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05-23-2022, 09:39 PM | #9 |
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Ident exhaust set-up. DCT. Same brrrap/pop…on it hard to say 4k and quick let off. I like it…especially arousing in a tunnel or parking garage.
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05-24-2022, 08:34 AM | #10 |
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Dislike that sound too, the more open / free flowing the exhaust the more pronounced. Its it just diverted air going into the exhaust (left over boost)?
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05-24-2022, 11:10 AM | #11 |
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Yeah good point. To clarify, it's not the "braap" sound on throttle lift but instead the "POP" that happens after the braap sound
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05-24-2022, 11:07 PM | #12 |
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The braaap is fast acting ignition timing pull (fast ignition retard) to force the engine revs down. It isn't there for the sound as much as it is there to perform its function. I guess the leftover pops are just more fuel in the fast decel phase. Only tuning would be able to reduce that. Or just put in a quieter exhaust.
The first time I heard such a sound was with the Ferrari 360 F1 transmission cars on upshift. It's there to drop the rpm fast. Too bad it doesn't sound like this.
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-2019 M2 Competition MT, Alpine White. Self-tuned 560hp -2016 Mini Cooper S, MT. Many plans. Others: -E36 328is. 2000 Z3 Roady. 2003 VW Jetta TDI Manual. Estoril Z3M Coupe. Last edited by Enabled; 05-24-2022 at 11:18 PM.. |
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05-25-2022, 07:36 AM | #13 | |
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Glad to know I can tune out the burbles and keep the BARK!
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05-26-2022, 04:33 PM | #14 |
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You want to remove the anti-lag pop when changing gears?
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05-26-2022, 05:19 PM | #15 |
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My understanding is that it's just leftover boost going through the engine. Our cars do not have a blowoff valve. I think BMW just opens up the valves and lets the pressure wave blow through the cylinders with no added fuel. The pressure wave then hits the exhaust side of the turbo and keeps it spooled.
(Normally, you'd need a blowoff valve as there is pressurized air after the turbo that has nowhere to go when the throttle body is suddenly closed. BOV's vent to atmosphere or back to the intake on the non-pressurized side of the turbo. Without one, that pressurized air would essentially bounce off the throttle body and hit the turbo(s) going the wrong direction, rapidly slowing them down. Which is super bad for them and also kills all boost.) Unless i'm totally mistaken, that sound is both serving to extend the longevity of the turbos and providing an anti-lag-like effect. Last edited by Moflow; 05-26-2022 at 05:24 PM.. |
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05-27-2022, 08:07 AM | #16 | |
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Basically I have an unresonated AA midpipe, I would be open to adding resonated connecting pipes if that helps decrease the volume of the "pop" but I'm not sure if it would?
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05-27-2022, 11:45 AM | #17 |
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05-27-2022, 01:04 PM | #18 | |
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05-27-2022, 01:07 PM | #19 | ||
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06-01-2022, 03:01 PM | #20 |
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Welcome!
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