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2010 2011 BMW 5 Series Forum F10 F10 Technical Topics Engine, Transmission, Exhaust, Drivetrain, ECU Software Modifications Scavenging/Back Pressure
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      06-19-2020, 09:42 AM   #1
spielnicht
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Scavenging/Back Pressure

While I love my Dinan exhaust, I hate the back pressure noise it produces while in Sport mode. Honestly, this is the main reason I didn't keep the M5 mufflers on my 550i (it was way more pronounced though). This is definitely a scavenging issue created by aftermarket mufflers (or mufflers not made specifically for the car).

Does anyone have any experience in how to reduce or eliminate the noise? I've read replacing the center resonators with an x-pipe could eliminate this, but I need to be sure before considering the cost.
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      06-19-2020, 10:15 AM   #2
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Back pressure noise? You mean drone? Not sure why mufflers would affect scavenging on a turbo charged car lol
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      06-19-2020, 10:50 AM   #3
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It's not drone. The Dinan has zero drone for the most part (which is why I went with it). The noise I'm speaking of only comes in Sport mode when you're WOT and release your foot off of the pedal at once. If you release the pedal slowly after WOT, you can avoid the noise.
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      06-19-2020, 04:24 PM   #4
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no idea what you mean? can you post a video?
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      06-19-2020, 07:07 PM   #5
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Quote:
Originally Posted by lsturbointeg View Post
no idea what you mean? can you post a video?
I'll try to get a video this weekend.
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      06-20-2020, 12:51 AM   #6
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Do you mean burbles?
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      06-20-2020, 10:15 AM   #7
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Quote:
Originally Posted by spielnicht View Post
It's not drone. The Dinan has zero drone for the most part (which is why I went with it). The noise I'm speaking of only comes in Sport mode when you're WOT and release your foot off of the pedal at once. If you release the pedal slowly after WOT, you can avoid the noise.
Sounds more like you're hearing the wastegate/blow off, which has nothing to do with what muffler you've fitted.

Personally, I don't think there's anything to a scavenging/resonance/pressure wave timing concern with a turbocharged engine. The turbines in the exhaust path are pretty much the biggest factor, and they smooth out pulses and sound. To maximize the energy harvested by the turbocharger you want the greatest thermodynamic gradient across the exhaust turbine, part of which is greatest pressure differential across the turbine.

Second, these aren't normally aspirated Hondas with VTEC, <2.0L displacement, 8k redlines and 2" exhausts. An N55 starts with ~300hp/300tq and gets substantial gains from a flash tune and no other changes. That means that the intake, exhaust, air filter, downpipe, cats, LPFP, HPFP, injectors and all that other stuff that people rush to upgrade were never limiting factors in the first place for stock equipment - software was.

I put my MPE on for the sound and character, to remind me of past driving experiences and give the car a little bit of soul/character. I could not care less about "power gains" - and I neither expect nor observe any.

I am interested in claims that the Dinan is drone-free. Drone is something that bothers me about the MPE, but I see equal numbers of owners claiming the MPE drones less than the Dinan on an N55. I would have to meet up with a Dinan owner on an N55 to assess for myself.
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      06-20-2020, 09:22 PM   #8
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I had both. Dinan is heavier ( thicker gage metal) and quieter than M Performance.
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      06-23-2020, 11:30 PM   #9
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I had both. Dinan is heavier ( thicker gage metal) and quieter than M Performance.
This is a search I'm constantly on. I want the right sound and just haven't found it yet. I had magnaflow with a resonator removed on my e46 and loved the sound of that car. I am not overly sold on magnaflows f10 mufflers all that much. Anyone have sound clips? I've looked at both dinan and m. I don't really want burbles so not a huge concern. But I also think if not going full valvetronic, and with the CA emissions I have to go with something more OTS.
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      06-24-2020, 12:06 AM   #10
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Quote:
Originally Posted by zcali925 View Post
This is a search I'm constantly on. I want the right sound and just haven't found it yet. I had magnaflow with a resonator removed on my e46 and loved the sound of that car. I am not overly sold on magnaflows f10 mufflers all that much. Anyone have sound clips? I've looked at both dinan and m. I don't really want burbles so not a huge concern. But I also think if not going full valvetronic, and with the CA emissions I have to go with something more OTS.
Check out remus. Unfortunately sound clips just aren't that reliable, everyone's mic setups are different and the same exhaust will sound different on two different mic setups.
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      06-24-2020, 10:07 AM   #11
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Quote:
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Check out remus. Unfortunately sound clips just aren't that reliable, everyone's mic setups are different and the same exhaust will sound different on two different mic setups.
Not to mention most people just post sound clips of cold start (why is that cool?) followed by revving to redline in their driveway with a camera shoved up the exhaust tip.

I don't know how anyone can make a purchase decision based on that, unless that precisely matches your intended use case. My accelerator pedal has more than two positions and in almost all cases where I'm using it, the car is moving.

None of these things tell me that the bass line of my music will be drowned out on every highway trip, or whether following me driving at 6/10 shows a subtle aggressiveness or whether I sound like an old fart with a 3/4-life crisis that's trying too hard.

I had an E39 with a Dinan exhaust. Now, this was all normally aspirated, so sounds different, and Dinan had one exhaust for the E39 regardless of whether it was a 516i or a 540i so it wasn't specifically tuned for V8 or I6 (though I suspect that the V8 was their design target). I had an I6 and it had absolutely no drone once you were crusing in any gear, a smooth subtle idle rumble, a barking rev-match downshift, and swept the 2.5-5.5k range of the tach at mid-throttle with a beautiful melodious sound like a supercar (an I6 reduced to a single exhaust is half a V12 after all). The turbocharger and dual exhaust set up pretty much kill ever getting that on an F10 535.

I was on the highway the other night with the windows down and heard a snippet of that 3500-5000rpm I6 Dinan song, snapped my head over and saw a beautiful E34 with MT smoothly slicing through the traffic. Could have been an M5, not sure - dark out and no badges.

Sorry, what were we talking about? Oh yeah, choosing an exhaust on YouTube is hard.
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      06-24-2020, 12:24 PM   #12
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Quote:
Originally Posted by Surly73 View Post
Not to mention most people just post sound clips of cold start (why is that cool?) followed by revving to redline in their driveway with a camera shoved up the exhaust tip.

I don't know how anyone can make a purchase decision based on that, unless that precisely matches your intended use case. My accelerator pedal has more than two positions and in almost all cases where I'm using it, the car is moving.

None of these things tell me that the bass line of my music will be drowned out on every highway trip, or whether following me driving at 6/10 shows a subtle aggressiveness or whether I sound like an old fart with a 3/4-life crisis that's trying too hard.

I had an E39 with a Dinan exhaust. Now, this was all normally aspirated, so sounds different, and Dinan had one exhaust for the E39 regardless of whether it was a 516i or a 540i so it wasn't specifically tuned for V8 or I6 (though I suspect that the V8 was their design target). I had an I6 and it had absolutely no drone once you were crusing in any gear, a smooth subtle idle rumble, a barking rev-match downshift, and swept the 2.5-5.5k range of the tach at mid-throttle with a beautiful melodious sound like a supercar (an I6 reduced to a single exhaust is half a V12 after all). The turbocharger and dual exhaust set up pretty much kill ever getting that on an F10 535.

I was on the highway the other night with the windows down and heard a snippet of that 3500-5000rpm I6 Dinan song, snapped my head over and saw a beautiful E34 with MT smoothly slicing through the traffic. Could have been an M5, not sure - dark out and no badges.

Sorry, what were we talking about? Oh yeah, choosing an exhaust on YouTube is hard.
We should find a rich dude with a F10, have him buy every exhaust setup, and have a standardized mic setup to test each one. Then we'll have a library of exhausts.

One can dream.
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      06-24-2020, 10:38 PM   #13
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Quote:
Originally Posted by Unspec View Post
We should find a rich dude with a F10, have him buy every exhaust setup, and have a standardized mic setup to test each one. Then we'll have a library of exhausts.

One can dream.
If he's that rich he can fly us all out to listen in person.
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      06-24-2020, 11:37 PM   #14
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Quote:
Originally Posted by Surly73 View Post
Quote:
Originally Posted by Unspec View Post
We should find a rich dude with a F10, have him buy every exhaust setup, and have a standardized mic setup to test each one. Then we'll have a library of exhausts.

One can dream.
If he's that rich he can fly us all out to listen in person.
Sounds reasonable.
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