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      08-19-2012, 01:56 PM   #23
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Originally Posted by m3alabama View Post
More inaccurate information as usual. Hemoltz don't operate at an all or none state. Their dimensions and the sound level simply are factors in which area of the RPM 's the sound is balanced out.

ACM mod is absolutely nothing like straight pipes. The backfiring and "popping" from straight pipes sounds like trash whereas there is virtually no popping or backfire.

Plus the straight pipes are a much less refined sound.

Dude relax. Shorter heimholtz chambers that are designed for Lower volumes will be over run with drone with either setup. You need longer ones like the AA setup. Secondly backfiring and popping?? Trash?? Is this first hand info??

Like I stated, I have had both, and the straight pipes do not pop and backfire. Hell my Gintani Race is very poppy on deceleration.


And you wonder why people call you a troll. The first word you type is always negative, you sound like a know it all, and you really don't know everything (proven by all your other useless posts). Relax and stick around, maybe you'll learn something.
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      08-19-2012, 02:04 PM   #24
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Here you go Alabama, just for you: this explains formula and based on the frequency you need to eliminate determines the length of pipe. "Simply put, the formula for determining the length of a Helmholtz chamber used to knock out a drone frequency is:

1100 feet/second (roughly the speed of sound) divided by the target frequency you're trying to eliminate (in cycles/second) gives a full wavelength in feet per cycle. Divide this number by 4 to get a quarter wavelength (a much more convenient length to work with). Finally, multiply this wavelength by 12 to get the chamber length in inches.

Tap this length of pipe into the exhaust tube, making sure the other end of the pipe is capped off, and you have a Helmholtz chamber that takes the annoying frequency and bounces it back into the flow 180 degrees out of phase, knocking it out. The results: no more drone"
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      08-19-2012, 02:06 PM   #25
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Quote:
Originally Posted by m3alabama View Post
More inaccurate information as usual. Hemoltz don't operate at an all or none state. Their dimensions and the sound level simply are factors in which area of the RPM 's the sound is balanced out.

ACM mod is absolutely nothing like straight pipes. The backfiring and "popping" from straight pipes sounds like trash whereas there is virtually no popping or backfire.

Plus the straight pipes are a much less refined sound.
I had to quote this again, as when I re-read it, it doesn't make any sense at all
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      08-27-2012, 05:23 AM   #26
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So based on experience would the OEM mod (welding straight pipes all the way through) produce a favorable sound without any power loss or back pressure issues? Has anyone done it and done a dyno comparison? I looking for some seriously loud and low pitch results. I have the ability to drop the entire exhaust and weld some pipe all the way through. Just want to know what kind of result I would get on my e92. I have done a complete straight pipe mod on a roush mustang in the past (cat delete, no restriction all the way through). It was an awesome result but roush mustang to e92 M3 is like apples and oranges. Anyone that has experience in this please throw down your 2 cents (pics,vids or diagrams would be favorable. Thanks
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      08-27-2012, 04:39 PM   #27
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So based on experience would the OEM mod (welding straight pipes all the way through) produce a favorable sound without any power loss or back pressure issues? Has anyone done it and done a dyno comparison? I looking for some seriously loud and low pitch results. I have the ability to drop the entire exhaust and weld some pipe all the way through. Just want to know what kind of result I would get on my e92. I have done a complete straight pipe mod on a roush mustang in the past (cat delete, no restriction all the way through). It was an awesome result but roush mustang to e92 M3 is like apples and oranges. Anyone that has experience in this please throw down your 2 cents (pics,vids or diagrams would be favorable. Thanks
I have driven an E92 M3 with ACM mod with CATless x-pipe non-resonated and it was crazy loud. My friend took it off right a way. not a good idea. I don't think anyone keep it long enough to dyno it.
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      10-09-2012, 10:44 PM   #28
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I had the AA axle back and it droned pretty bad below 2800RPM. I don't know if their Helmholtz chambers were adequately sized or not. I sold it to a buddy after 8 months of DD'ing it. We did the install ourselves and thought it'd be fun to check out his car without the muffler. We did a 15 min drive with a mix of short fwy and surface roads. I'm not sure how muffler delete and straight pipes compare technically but I can tell you that the drone unbearable.

So from personal experience, AA drones below 3k and muffler delete has unbearable drone.

m3an - are Helmholtz chambers an all or nothing deal? Meaning does having a smaller chamber still work to cancel out some drone or none at all?
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