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      01-15-2013, 03:22 AM   #1
tikamak
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Z4M Euro headers - decat Spipe - stock Xpipe - Rogue Engineering El diablo muffler

Thoughts? i hope the quality is good enough, it was taken from my friend's iphone.

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      01-15-2013, 04:14 AM   #2
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Thought it would sound raspier. That's not bad at all.
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      01-15-2013, 05:00 AM   #3
tikamak
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Yes because I left the stock Xpipe resonator and I emptied the Spipe cats leaving it to pseudo-resonate. (+ something I did secretly)
This transformed the rasp quality into a hollowish howling sound, more like a V10 V12 kind of rasp. the diablos have as well this kind of hollow howling bassy sound.

The engine metallic shriek is amplified intensly with this setup and it feels like a traditional BMW ///M motorsport sound especially when the revs climb, it sounds like an F1 car passing by.

Sometimes downshifting 2nd and flooring it next to a wall helps me listen to the car and it sounds like a catless gallardo.

Shifting abruptly makes some minor backfire and a whole lot of crackling and popping and burbles.

Let me know if you need any other information and happy decatting, there is some serious power to be had when decatting.
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      01-15-2013, 07:20 PM   #4
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What is your secret sauce :-)
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      01-28-2013, 05:07 AM   #5
tikamak
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The secret sauce is that when emptying the Cats, i have wrapped them with an extra layer of sheet metal to help the pseudo resonation nature of the emptied Katalysor chamber.

This will help the raspy sounds get in sync with the engine note and will create a sort of an aggressive metallic sound that basically represents our S54 tone. The sound is no way near any ricer car, the boomy nature of the Diablos is pretty much gone with the free flow and the DKF hangers.

People's reaction to the car's exhaust when taking a ride:
* Highly tuned exhaust sound
* Amazingly loud but not disturbing at all, not even 1 bit
* Sounds like a Scuderia at full throttle
* How much does it rev? 10K RPM?
* That's a BMW bike
* The best part is downshifting
* What's that tinny grinding noise when you're at half load?
* ...
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      01-28-2013, 11:23 PM   #6
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Thanks for sharing. Your car sounds nice.
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      01-29-2013, 07:06 AM   #7
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that does sound really nice. how did you do the sheet metal? did you tune it specifically for a frequency range or just put some metal over the top? how did you secure it? (sorry for so many questions)
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      01-29-2013, 12:57 PM   #8
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Cool, but you do understand that half of your "secret sauce" efforts are non scientifically sound without empirical data, so I'm guessing you just tried this out and lucked out! Engineers tune exhaust using CAD flow analysis and modeling software, and run experiments to verify results. Adding a hollow chamber adds volume to your exhaust piping, which can amplify or dampen certain exhaust frequencies. F1/Gallardo sound claims don't make sense since those engines are flat-crank, which gives them that specific dual-frequency sound (ala F355).

But, to make the S54 free flow, yet not sound "rice", is not easy, so it is great that you've gotten close with minimal efforts!

*Edit: I just realized it still sounds like a honda!

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      01-30-2013, 03:17 AM   #9
tikamak
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The tuning of the exhaust has already been done by BMW engineers my friend, i didn't create a new exhaust, i'm just showing you what worked for me.

the cat chambers are designed to have a certain resonation frequency with the cats installed, when emptying it, this will amplify rasp into rice level due to having a different resonation. when you put bent sheet metal and weld it, the are will be sturdier and the resonation frequency will be closer to when the cats are there.

I didn't understand your comment about a flat-crank, do you mean boxer engine? because a gallardo for example is a V10 with 90 degrees and the duality in the sound comes from intake and exhaust i suppose. Please explain.

The video is very very low quality as it was taken from an iphone, i assure you that the sound is no way near any honda with an exhaust. I've had expert porsche and ferrari mechanics drive my car and they have said that this sound is very addictive and up there with supercar quality. one of them also called it "traditional B-M-V exhaust note" (he's german so the W is a V)
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      01-30-2013, 06:44 AM   #10
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Quote:
Originally Posted by tikamak View Post
The tuning of the exhaust has already been done by BMW engineers my friend, i didn't create a new exhaust, i'm just showing you what worked for me.

the cat chambers are designed to have a certain resonation frequency with the cats installed, when emptying it, this will amplify rasp into rice level due to having a different resonation. when you put bent sheet metal and weld it, the are will be sturdier and the resonation frequency will be closer to when the cats are there.

I didn't understand your comment about a flat-crank, do you mean boxer engine? because a gallardo for example is a V10 with 90 degrees and the duality in the sound comes from intake and exhaust i suppose. Please explain.

The video is very very low quality as it was taken from an iphone, i assure you that the sound is no way near any honda with an exhaust. I've had expert porsche and ferrari mechanics drive my car and they have said that this sound is very addictive and up there with supercar quality. one of them also called it "traditional B-M-V exhaust note" (he's german so the W is a V)
Here's some good info about flat plane crankshafts..

http://www.projectm71.com/Cross_FlatPlane.htm
http://www.autozine.org/technical_sc...ne/smooth4.htm

Flat plane engines are basically less refined and smooth, which is why they're typically only used in exotic sports cars where one doesn't care so much about how "buzzy" they might sound.
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      01-30-2013, 09:29 AM   #11
tikamak
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Interesting information to share with me, thank you for that.
The new Lambos and ferraris have cross-planed crankshaft designs.

Italia 458 for example.

In all cases, it is not possible to compare an inline 6 to a V8 or a V10, my comparison was based on tone and volume rather than the complexity of the engine exhaust sound simulating firing order.

Let's just leave it at that. did you like the sound?

Last edited by tikamak; 01-30-2013 at 09:40 AM.
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