Looking forward to seeing it next week. Hopefully u can have a listen my exhaust and suggest some ideas to reduce the drone.
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Active NSX Exhaust System
- Thread starter Mac Attack
- Start date
Hi Cassius, how's your project going?
I don't have sound clips yet - hopefully cwood1388 can help me when he gets some free time.
I did go back and lengthen the little 1.5" exhaust tips by 6" each to blend better with my diffusor. That also shifted the 3rd harmonic frequencies I was trying to resonate down to the 2nd harmonic EFR frequencies between 2500-4000 RPM's. So, now these resonate a little louder, but at lower frequencies. Since I don't use a "muffler" to filter out the lower frequencies, I think the higher-frequency 3rd harmonics I was trying to resonate just wasn't loud enough (not enough driving amplitude) to hear over the rest of the noise.
Unfortunately, if I tune for any further sound improvements, it's just going to add weight. 26 lbs for the existing cat/piping is all I'm willing to go. If I had access to lighter, thinner-walled stainless steel (and knew how to weld better) then I could come up with a killer system. But, it's time to move on to other projects!
I really like how it sounds now, but of course, what sounds good is subjective to each of us. I hope this is an inspiration for others here to come up with their own unique, free-flowing systems that don't drone :biggrin:
Dave
I don't have sound clips yet - hopefully cwood1388 can help me when he gets some free time.
I did go back and lengthen the little 1.5" exhaust tips by 6" each to blend better with my diffusor. That also shifted the 3rd harmonic frequencies I was trying to resonate down to the 2nd harmonic EFR frequencies between 2500-4000 RPM's. So, now these resonate a little louder, but at lower frequencies. Since I don't use a "muffler" to filter out the lower frequencies, I think the higher-frequency 3rd harmonics I was trying to resonate just wasn't loud enough (not enough driving amplitude) to hear over the rest of the noise.
Unfortunately, if I tune for any further sound improvements, it's just going to add weight. 26 lbs for the existing cat/piping is all I'm willing to go. If I had access to lighter, thinner-walled stainless steel (and knew how to weld better) then I could come up with a killer system. But, it's time to move on to other projects!
I really like how it sounds now, but of course, what sounds good is subjective to each of us. I hope this is an inspiration for others here to come up with their own unique, free-flowing systems that don't drone :biggrin:
Dave
Hey Dave it was good to see you and your daughter and the NSX Fla
Let me know if you need to get Chris off his ass. I'l come up and help over the holidays I'm off the week!!
Let me know if you need to get Chris off his ass. I'l come up and help over the holidays I'm off the week!!
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lol
She's been sitting outside the past few nights in the cold (and snow), so today I thought I would take her out for a spin and get some gas.
I'm really happy with the sound in loud mode, and the fact there is no droning quiet or loud mode. But, I've been thinking a little more, and believe there is an even simpler layout to shed even more weight (make it even less than the current 26 pounds with valve and cat). We'll see!
This was taken with a cell phone, compressed to upload/download quickly, and then is played back with whatever setup you may have, so take this with a grain of salt :wink:
Quiet Mode:
<iframe src="http://player.vimeo.com/video/18223731" width="400" height="300" frameborder="0"></iframe><p><a href="http://vimeo.com/18223731">New Quiet Mode NSX Muffler</a> from <a href="http://vimeo.com/user1744194">Dave</a> on <a href="http://vimeo.com">Vimeo</a>.</p>
Loud Mode:
<iframe src="http://player.vimeo.com/video/18223839" width="400" height="300" frameborder="0"></iframe><p><a href="http://vimeo.com/18223839">New Loud Mode NSX Muffler</a> from <a href="http://vimeo.com/user1744194">Dave</a> on <a href="http://vimeo.com">Vimeo</a>.</p>
I'm really happy with the sound in loud mode, and the fact there is no droning quiet or loud mode. But, I've been thinking a little more, and believe there is an even simpler layout to shed even more weight (make it even less than the current 26 pounds with valve and cat). We'll see!
This was taken with a cell phone, compressed to upload/download quickly, and then is played back with whatever setup you may have, so take this with a grain of salt :wink:
Quiet Mode:
<iframe src="http://player.vimeo.com/video/18223731" width="400" height="300" frameborder="0"></iframe><p><a href="http://vimeo.com/18223731">New Quiet Mode NSX Muffler</a> from <a href="http://vimeo.com/user1744194">Dave</a> on <a href="http://vimeo.com">Vimeo</a>.</p>
Loud Mode:
<iframe src="http://player.vimeo.com/video/18223839" width="400" height="300" frameborder="0"></iframe><p><a href="http://vimeo.com/18223839">New Loud Mode NSX Muffler</a> from <a href="http://vimeo.com/user1744194">Dave</a> on <a href="http://vimeo.com">Vimeo</a>.</p>
wow, from the sound alone... they both sound awesome! while being functional and lightweight too!
It gives me kind of an BMW M3 vibe 
Sounds great!
My own little project has come to the point of calculations so far, I need to check a couple of parameteres before I build a muffler/sound enhancer of my own! And for that I need to get the car going first... But all good comes to those who wait, right?
Sounds great!My own little project has come to the point of calculations so far, I need to check a couple of parameteres before I build a muffler/sound enhancer of my own! And for that I need to get the car going first... But all good comes to those who wait, right?
I like your cloaking device when you appear and disappear.....
Thanks, I told my 2.5 YO daughter not to touch any of the buttons but she doesn't listen to me.
How did your exhaust turn out?
Dave
It's in the shop getting ceramic coated white - all the way to the tips.
Imagine the contrast from black to white.
Might have to change my name to Penguin.
I should get it back the week after the New Years.
Videos and pics will follow....
Darn broken video links. Anyone do something similar? Ping me on fb at joe bez
The three people I know who did a full active system are [MENTION=20915]RYU[/MENTION], [MENTION=12356]Mac Attack[/MENTION] and [MENTION=4318]ANYTIME[/MENTION]
but anything off the shelf right now that I can buy? assume no. it is a custom job. SOS does not offer this (i asked). my NSX has an ANYTIME exhaust on it already.
The closest off the shelf that i'm aware of is from RF Yamamoto. You can order from him in Japan.
You can order this with a valve http://www.rf-yamamoto.com/NSXexhaust/2.html . Not sure if the valve is pneumatic or electronic.
Over the past 15 years I've gone through at least 30 different exhaust configurations of my own design (the engineer in me always wanting to try things out and optimize parameters). Three of those were for my custom turbo setup and the rest were trying to balance pressure drop, weight, sound, drone, and layout (for aero and aesthetics). At the beginning I tried to focus more on some aspects and sacrifice others so I would know what I wanted to compromise on. Also, a lot of these old posts were when I was learning about how to eliminate drone and accentuate some desired frequencies, and testing out some wild ideas.
Here's a vimeo link to five very different designs from about 12 years ago:
https://vimeo.com/user1744194
There is no perfect design, even with my many different valve configurations over the past ten years. It all depends what you would like to emphasize and sacrifice in exchange. Now I prefer the synthesized soundtracks to my extremely fast electric cars when accelerating and their silence when cruising.
But, I still have two 600+HP hybrids (that burn gas and rubber) and the NSX. The current NSX exhaust configuration goes from the headers into two equal length 1.75" pipes into a 2.5" collector. From there into a 100 cell cat and then a single Borla Pro XS muffler and out the drivers side of the rear end. It's low pressure drop, light weight, relatively free-flowing for my 350 WHP ITB'd engine, and very nicely packaged to allow a huge diffuser. For sound all I wanted was zero drone and no rasp. The intake sound is what I was trying to accentuate at this stage.
Ah, that one used the technology I'd developed as discussed in the PMs. Sounds awesome but somewhat restrictive. That was with '97+ manifolds. It combined technology Dave Borla patented a few years ago (I'd actually done it first but the patent laws changed around 2014 from first to do it to first to file so I lost my claim). That's how he got it. It also combined another one of my ideas that hasn't been patented yet and I may still do so as I recently retired. So, that info won't be divulged here yet.
