NSX F1 Exhaust Can Be Done!

I was thinking of doing something like this but no time at the moment!

Props to Mac, this a sweet sounding setup. Count me in for the first production run.
 
Took a quick video on the way to work this morning. The first segment is a leisurely acceleration through 1st and 2nd up to around 7k RPM. The flyby is accelerating from 5-7k RPM:
<iframe src="http://player.vimeo.com/video/24317079?title=0&byline=0&portrait=0" width="400" height="300" frameborder="0"></iframe><p><a href="http://vimeo.com/24317079">Untitled</a> from <a href="http://vimeo.com/user1744194">Dave</a> on <a href="http://vimeo.com">Vimeo</a>.</p>

This is still the loud mode with exhaust going direct from the headers through 2.25” and 3” piping to basically straight out the back. There’s a little muffler and some flow/resonance tuning, but it is about as free-flowing and power-producing as you’ll get. Needless to say, I love it! With an aluminum tuned resonator to cancel the drone frequency, it’s actually not that bad for daily-driving if you can get over the stench from not having my cats piped in (which they will be this weekend when I get my new quiet muffler welded in).

I’ve also learned a lot about exhaust piping material resonances. Most of the “rasp” in exhausts comes from exhaust piping material resonances. Given the same dimensions (pipe diameter, wall thickness, and length), different materials greatly influence the resonance sound and give some exhausts their characteristic “ring,” ala Kreisiegg, Capristo, Aprakovic, etc. Because I use cheap, light 18ga carbon steel, I tend to get rasp. Interestingly, the rasp only forms above 4k RPM, and I notice that if I accelerate moderately up to around 4k RPM and then exceed it, I avoid the rasp. i.e., once the 4k RPM excitation frequency passes from the engine, if the exhaust material isn’t already ringing, rasp doesn’t form above this RPM. But, if I go WOT through the rev band, the rasp forms at 4k RPM and just keeps ringing until redline. Even if I do let the rasp form, I would say that it’s no worse than the pretzel exhausts out there, but I still don’t really care for it.

I’m getting a Flowmaster 60-series 2” muffler in the mail today. Hopefully it will be quiet enough in conjunction with my cat to make it daily-driver friendly. The only problem is that it weighs ~13-14 pounds. Oh well. Total with cats/valve will be around 35 pounds, which is still about the best you can get with this performance potential, sound, and then having it very quiet when needed.

Not quite LFA, Ferrari, or F1, but it’s definitely as close as you’ll get to those from our engine, and it has it’s own unique sound. I can finally say it’s time to now focus on my aero mods and then do my engine rebuild….

Dave
 
That sounds awesome!
 
Mac Attack said:
Took a quick video on the way to work this morning. The first segment is a leisurely acceleration through 1st and 2nd up to around 7k RPM. The flyby is accelerating from 5-7k RPM:

This is still the loud mode with exhaust going direct from the headers through 2.25” and 3” piping to basically straight out the back. There’s a little muffler and some flow/resonance tuning, but it is about as free-flowing and power-producing as you’ll get. Needless to say, I love it! With an aluminum tuned resonator to cancel the drone frequency, it’s actually not that bad for daily-driving if you can get over the stench from not having my cats piped in (which they will be this weekend when I get my new quiet muffler welded in).

I’ve also learned a lot about exhaust piping material resonances. Most of the “rasp” in exhausts comes from exhaust piping material resonances. Given the same dimensions (pipe diameter, wall thickness, and length), different materials greatly influence the resonance sound and give some exhausts their characteristic “ring,” ala Kreisiegg, Capristo, Aprakovic, etc. Because I use cheap, light 18ga carbon steel, I tend to get rasp. Interestingly, the rasp only forms above 4k RPM, and I notice that if I accelerate moderately up to around 4k RPM and then exceed it, I avoid the rasp. i.e., once the 4k RPM excitation frequency passes from the engine, if the exhaust material isn’t already ringing, rasp doesn’t form above this RPM. But, if I go WOT through the rev band, the rasp forms at 4k RPM and just keeps ringing until redline. Even if I do let the rasp form, I would say that it’s no worse than the pretzel exhausts out there, but I still don’t really care for it.

I’m getting a Flowmaster 60-series 2” muffler in the mail today. Hopefully it will be quiet enough in conjunction with my cat to make it daily-driver friendly. The only problem is that it weighs ~13-14 pounds. Oh well. Total with cats/valve will be around 35 pounds, which is still about the best you can get with this performance potential, sound, and then having it very quiet when needed.

Not quite LFA, Ferrari, or F1, but it’s definitely as close as you’ll get to those from our engine, and it has it’s own unique sound. I can finally say it’s time to now focus on my aero mods and then do my engine rebuild….

Dave
Click to expand...

Hi Dave,

Congrats to a nice exhaust build! People are lining up for you to produce a couple of sets. I'm one of them =)

If you don't want to make them yourself, please sell the design to someone else so they can start producing it!

I NEED IT TO!
 
Mac Attack said:
Took a quick video on the way to work this morning. The first segment is a leisurely acceleration through 1st and 2nd up to around 7k RPM. The flyby is accelerating from 5-7k RPM:
<iframe src="http://player.vimeo.com/video/24317079?title=0&byline=0&portrait=0" width="400" height="300" frameborder="0"></iframe><p><a href="http://vimeo.com/24317079">Untitled</a> from <a href="http://vimeo.com/user1744194">Dave</a> on <a href="http://vimeo.com">Vimeo</a>.</p>

This is still the loud mode with exhaust going direct from the headers through 2.25” and 3” piping to basically straight out the back. There’s a little muffler and some flow/resonance tuning, but it is about as free-flowing and power-producing as you’ll get. Needless to say, I love it! With an aluminum tuned resonator to cancel the drone frequency, it’s actually not that bad for daily-driving if you can get over the stench from not having my cats piped in (which they will be this weekend when I get my new quiet muffler welded in).

I’ve also learned a lot about exhaust piping material resonances. Most of the “rasp” in exhausts comes from exhaust piping material resonances. Given the same dimensions (pipe diameter, wall thickness, and length), different materials greatly influence the resonance sound and give some exhausts their characteristic “ring,” ala Kreisiegg, Capristo, Aprakovic, etc. Because I use cheap, light 18ga carbon steel, I tend to get rasp. Interestingly, the rasp only forms above 4k RPM, and I notice that if I accelerate moderately up to around 4k RPM and then exceed it, I avoid the rasp. i.e., once the 4k RPM excitation frequency passes from the engine, if the exhaust material isn’t already ringing, rasp doesn’t form above this RPM. But, if I go WOT through the rev band, the rasp forms at 4k RPM and just keeps ringing until redline. Even if I do let the rasp form, I would say that it’s no worse than the pretzel exhausts out there, but I still don’t really care for it.

I’m getting a Flowmaster 60-series 2” muffler in the mail today. Hopefully it will be quiet enough in conjunction with my cat to make it daily-driver friendly. The only problem is that it weighs ~13-14 pounds. Oh well. Total with cats/valve will be around 35 pounds, which is still about the best you can get with this performance potential, sound, and then having it very quiet when needed.

Not quite LFA, Ferrari, or F1, but it’s definitely as close as you’ll get to those from our engine, and it has it’s own unique sound. I can finally say it’s time to now focus on my aero mods and then do my engine rebuild….

Dave
Click to expand...

WOW Dave, that sounds awesome - as you said, it's LOUD but awesome!
 
If Dave decides to keep the design to himself I would not be one to hold it against him. We all love class touches that make our cars truely unique. Well, how about having the only NSX anywhere that sounds like Dave's. I have never heard an exhaust system produce a sound from a V6 that I liked better. I recon that after all the man-hours and money Dave has put into this project he has earned the right to share it or keep it one of the most exclusive systems [Jeremy Clarkson voice]in the world[/Jeremy_Clarkson_voice].

But I sure hope he decides to market it because I want.
 
Last edited:
tof said:
If Dave decides to keep the design to himself I would not be one to hold it against him. We all love class touches that make our cars truely unique. Well, how about having the only NSX anywhere that sounds like Dave's. I have never heard an exhaust system produce a sound from a V6 that I liked better. I recon that after all the man-hours and money Dave has put into this project he has earned the right to share it or keep it one of the most exclusive systems [Jeremy Clarkson voice]in the world[/Jeremy_Clarkson_voice].

But I sure hope he decides to market it because I want.
Click to expand...

You are wrong. Simply wrong. If I found a cure for cancer, am I not obligated to share this knowledge with humanity? Or if I come up with an engine that is fueled by water? Or if I design a super sexy, smokin hot super duper exhaust, as a matter a fact, the BEST SOUNDING EXHAUST FOR THE NSX [Jeremy Clarkson voice]in the world[/Jeremy_Clarkson_voice]?! =)

Dave, you are hereby, by authority of all NSX'rs in this community (except tof), obliged to share your invention by one of the two alternative means:

1. Produce a number of sets
or
2. Sell the design to someone who can fulfill #1 above

Think of it for a second, by doing this you may be able to fund your engine project, Dave! Strok'd, itb'd, you name it. You deserve it. You know you do.. Think of all the long hours and hard earned $$ you put in it. You can have it all back and more. Just pick up that phone and give STMPO a call. It's just a phone call. Do it or I tell your wife you blew a contract worth several thousands or tenths of thousands of dollars!

Ooops I think it got out of hand. I'm sorry, haven't had any sleep for the last 36 hours. My mind plays tricks on me. But I still need and crave this!
 
I've always wondered what it'd sound like. Very nice & thanks for sharing.
 
mr_goat said:
You are wrong. Simply wrong. If I found a cure for cancer, am I not obligated to share this knowledge with humanity? Or if I come up with an engine that is fueled by water? Or if I design a super sexy, smokin hot super duper exhaust, as a matter a fact, the BEST SOUNDING EXHAUST FOR THE NSX [Jeremy Clarkson voice]in the world[/Jeremy_Clarkson_voice]?! =)

Dave, you are hereby, by authority of all NSX'rs in this community (except tof), obliged to share your invention by one of the two alternative means:

1. Produce a number of sets
or
2. Sell the design to someone who can fulfill #1 above

Think of it for a second, by doing this you may be able to fund your engine project, Dave! Strok'd, itb'd, you name it. You deserve it. You know you do.. Think of all the long hours and hard earned $$ you put in it. You can have it all back and more. Just pick up that phone and give STMPO a call. It's just a phone call. Do it or I tell your wife you blew a contract worth several thousands or tenths of thousands of dollars!

Ooops I think it got out of hand. I'm sorry, haven't had any sleep for the last 36 hours. My mind plays tricks on me. But I still need and crave this!
Click to expand...

OK...You had me at "simply". :cool:
 
Thanks guys for the feedback. When I get a quiet version I'm pleased with I'll give this some serious thought.

Two problems though for a lot of NSX owners. With this setup, it is only center-exit, and you can't run a rear sway (which I prefer anyways).

Just figured out our van will be out of commission for another week, so I welded in a Flowmaster 60-series with a universal Magnaflow hiflo cat to quiet this down for this week of daily driving duties. It was just too loud and stinky before. Well, the 60 series quiets the exhaust at 2500 RPMs and up, but it's still pretty boomy below that. Also, it's amazing how much power the Flowmaster saps. It's really restrictive above 5k RPMs.

Sadly, in order to quickly weld it in, I had to sacrifice most of the setup in the previous videos. Gone is my valve, resonator tubes, and loud mode muffler.

Oh well, it will give me a chance to buy all new materials and make a "finished" product. I have to admit, after all the cutting, welding, recutting, rewelding, patching, etc. to do all these ideas, it was looking very hacked up.

Dave
 
Mac Attack said:
Thanks guys for the feedback. When I get a quiet version I'm pleased with I'll give this some serious thought.

Two problems though for a lot of NSX owners. With this setup, it is only center-exit, and you can't run a rear sway (which I prefer anyways).

Just figured out our van will be out of commission for another week, so I welded in a Flowmaster 60-series with a universal Magnaflow hiflo cat to quiet this down for this week of daily driving duties. It was just too loud and stinky before. Well, the 60 series quiets the exhaust at 2500 RPMs and up, but it's still pretty boomy below that. Also, it's amazing how much power the Flowmaster saps. It's really restrictive above 5k RPMs.

Sadly, in order to quickly weld it in, I had to sacrifice most of the setup in the previous videos. Gone is my valve, resonator tubes, and loud mode muffler.

Oh well, it will give me a chance to buy all new materials and make a "finished" product. I have to admit, after all the cutting, welding, recutting, rewelding, patching, etc. to do all these ideas, it was looking very hacked up.

Dave
Click to expand...

Center-exit is no problem for me:

IMG_294711.JPG


And I would sacrifice my rear sway bar for that sound, my car is a street car so I won't miss it, I would be to occupied listening to the engine!

By the way, if you are going to build a new system based on this design, why don't go with another material? Stainless/Alu/Titan maybe. Something that won't rust would be great =)
 
Nice car!

Carbon is cheap and soft to work with. That's why I've used it for developmental purposes. For the non-structural resonators, I use thin, light aluminum.

Would love to do titanium. Actually, if I could afford it, I would remake the OEM muffler out of thin-walled titanium, with provision via butterfly valves to bypass the cats and muffler when desired :wink: The designers went through a lot of analyses and trouble to make it - the only problem is that it is so big and heavy. Check it out - there are three main cavity resonators for each cylinder bank to cancel the low frequencies:

http://www.nsxprime.com/forums/showthread.php?t=68558

Dave
 
Mac Attack said:
Nice car!

Carbon is cheap and soft to work with. That's why I've used it for developmental purposes. For the non-structural resonators, I use thin, light aluminum.

Would love to do titanium. Actually, if I could afford it, I would remake the OEM muffler out of thin-walled titanium, with provision via butterfly valves to bypass the cats and muffler when desired :wink: The designers went through a lot of analyses and trouble to make it - the only problem is that it is so big and heavy. Check it out - there are three main cavity resonators for each cylinder bank to cancel the low frequencies:

http://www.nsxprime.com/forums/showthread.php?t=68558

Dave
Click to expand...

Thank you. I think your exhaust setup would compliment my car extremely well ^_^

Looking forward for more vids in the future. Can't stop listening to it!
 
RYU said:
Hey! Welcome back!
Click to expand...

+1, Just hasn't been the same!

BTW, sweet avatar.

Still deciding on a supercharger or ITB's w/ direct port nitrous. I keep flip-flopping but will probably go with a custom supercharger since I wold like to go back to daily-driving it.

Dave
 
Mac Attack said:
+1, Just hasn't been the same!

BTW, sweet avatar.

Still deciding on a supercharger or ITB's w/ direct port nitrous. I keep flip-flopping but will probably go with a custom supercharger since I wold like to go back to daily-driving it.

Dave
Click to expand...

Yea, during my stay at the Elizabeth Arkham Asylum Hotel I was able to gaze through the windows and notice that it's not the same.

What sorta custom Supercharger did you have in mind?

I really wish you can go with the Eaton TVS 2300 since it seems to out perform the all of the Twin Screw offerings from anyone with equal displacement at under 16psi (streetable boost).

http://www.moddedmustangs.com/forums/2005-2010/145169-tvs-vs-twin-screw.html
 

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