Nsx Muffler Cutaway and Modify - Pics Inside!

[ffffanman]

So I'm finally posting the pics of the Nsx muffler that we cut open at my friends sheetmetal shop. It was two layers of sheetmetal that Rod burnt through.
Also posting the two pics on prime I found in the past regarding the layout and someones view on the flow of the exhaust through the muffler.
I plane to modify this muffler and stick it on my car.
Whats you thoughts on what should be cut out or drilled or repipe'd in order to make a muffler that in your thoughts would help an n/a stock car run free'r and sound a little louder and nicer.
Once again, everyone will have their own thoughts, so let them fly.
This could be fun.
I did do some pressure drop tests before I opened it up.
Both sides where pretty close to having the same pressure loss.
Trev

 

[ffffanman]

more photos

 

[ffffanman]

and still more

 

[ffffanman]

And the Path Diagrams.

 

[fkong777]

Nice Job. Did the muffler have any type of steel or fiber wool material at all? What you think since you have the real deal in front of you.

BTW That was my flow diagram I modified from the service manual and photoshop.

Just my opinion.

Red cut out - cut out at lease half length of the exit pipe in the red area.. However this will make it really loud and with most flow.

Yellow cut out - Cut out the pipes on chamber 2 & 4. This should give it more flow than stock and still use most of the chambers.

 

[ffffanman]

There was no Material in the muffler.
There is so many different options here to try.
I like your ideas. Thanks for the original flow drawings.
Trev

 

[amgnsx]

How about do a straight pipe inside the muffler. So it will be loud :biggrin:
But if an officer pulls u over, show him your muffler and say “What do u mean Loud officer? it’s the OEM muffler and that’s how my car came from the Dealer” :biggrin: :biggrin: :biggrin:

 

[ffffanman]

But thats the thing, Its stock officer, honest!
Trev

 

[goldNSX]

Well I would say that it's a very complicated job here to get a little more sound and flow. Whatever you do here on your own I guess you'll need more than 5 tries (and errors ) with only the flow diagram. With five chambers you'll need a software to calculate back-pressure and resonances and so on. In the OEM muffler there's normally some material.
It's a very challanging and interesting job indeed. Please post some sound-files here before and after.

 

[ffffanman]

Thanks for the input.
After stare'n at these open cavities for awhile, i have decided to do the Red modification as suggested by fkong777.
Seems simple and the most drastic all in one.
Just going to take a sawsall and cut out about a 1.5" section there before the little silencer on the outlet. Weld her up and throw it on when the rebuilt transmission arrives next week from Chris @ SOS.
I will get the sound bites for you all.
Who can I send the too noisy tickets to?
Trev
p.s. There was no material in the muffler. You can see from the photos there is no material or residue from material being in there. This is a stock muffler from Lowdown Steve from his Black 91. Thanks Steve for letting me buy your muffler.

 

[john@johnhudakracing]

I can't see that any of this is worth it relative to just putting together a new design from scratch at any muffler shop - but as an added data point I will say that with everything else (intake, headers, pipes, top work, etc..) even a bone stock OE exhaust tends to get a little relatively noisey..

 

[ffffanman]

John, this is fun for me. Small things amuse me.
It costs nothing.
Its interesting to see what the stock unit is made of. People where always wondering. Now they know. Obviously Acura dedictated alot of time to designing this muffler. All those chambers and what do they do....
My own stock muffler is much louder that Eddies here in town and we have the same year car with no mods. I do like the sound of the stock unit and so do my older neighbors. Now the Harley on the other hand, that gets them freaked out.
I cant wait to hear what kind of monster I have created.
Trev

 

[ffffanman]

Well, the Modified muffler is on the car.
I took pressure drop reading before and after the modification.
The modification has free'd up the muffler a bit.
Initial pressure drop:
Drivers side - 24.5" of water column
Pass side - 22.0" of water column
Modified pressure drop:
Drivers side - 21.0" of water column
Pass side - 20.5" of water column
So, it looks like the flow is less restrictive now.
Will post the sound difference soon.
Not that big of difference that I can tell in the car.
Outside we will see.
Trev
Picture of Patch included. Patch faces up and is concealed by heat shield.

 

[lowdwnsteve]

Hey that muffler looks familiar!!
Nice work Trev!

 

[Cameron]

And the Path Diagrams.

OMG that diagram looks inefficient as hell, good write up and info though:smile:

 

[ffffanman]

Ok, so here are the two videos I did.
Can't tell that much difference, maybe a change to a lower tone.
Its good enough for me for now, until I have time to disect again!!!
Trev
http://www.nsxprime.com/photopost/data/500/9948NsxMufflerBeforeMod.AVI
http://www.nsxprime.com/photopost/data/500/9948NsxMufflerAfterMod.AVI

 

[Red]

Ok, so here are the two videos I did.
Can't tell that much difference, maybe a change to a lower tone.
Its good enough for me for now, until I have time to disect again!!!
Trev
http://www.nsxprime.com/photopost/data/500/9948NsxMufflerBeforeMod.AVI
http://www.nsxprime.com/photopost/data/500/9948NsxMufflerAfterMod.AVI

OK so I can tell a difference: In the second video "Aftermod.avi" a blonde walks up to the car and calls your name!

F&%K WHAT A MOD!

If I could do somehting to my car that could make that happen! :biggrin:

Talk about straightening your 'pipe!:wink:

 

[Russ]

Sounds awesome.

Anyone up for cutting open a Tubi?

 

[kidNSX]

I don't mean to hijack this thread - but am hoping for some opinions or experience with this. Where I live, no smog tests are required. I am thinking about replacing the two cats with straight pipes while retaining the stock muffler (a 98 car). Any thoughts whether the performance/sound improvements would be worth it? TIA for any opinions.

 

[fkong777]

Good Job fffffanman

It isnt that loud at all.. I guess most of the chamber are still doing work to buffer the exhaust pulses. Good mod... Thanks for being the Pioneer..

 

[ffffanman]

Think I'll drop it and cut more away. Probably cut out the crossover right in the middle out completely. Should have done that instead the first time, but was too scared it would be too loud.
Duh~!!!
Trev

 

[chussey]

Did you ever cut out the crossover pipe?

I just opened up my muffler and removed the red areas as well as the resonators after them. Going to see how loud it is tomorrow :biggrin:

 

[SuperSonic]

I don't mean to hijack this thread - but am hoping for some opinions or experience with this. Where I live, no smog tests are required. I am thinking about replacing the two cats with straight pipes while retaining the stock muffler (a 98 car). Any thoughts whether the performance/sound improvements would be worth it? TIA for any opinions.

1. Test pipes are bad ass
2. They will make your car go faster (me and lmr are dead even and he puts out 25 more hp to the wheels than me on a s/c car)
3. It sounds bad ass. Test pipes are in general bad ass


Fffffffffanman, what if you just connect the two inlets directly to outlets like an x inside the muffler. That should be sick.

 

[shawn110975]

I dont know Supersonic, I have been driving around with your old Pride V1 for about a week now and I am going nuts with the drone, I dont know how you guys do it. well mine is a DD so maybe thats why.

But I know when I drove your car from CA to FL I had your test pipes on and it did have a deeper sound than just the V1 alone.

I have not heard a car with the X type pipes but I think they would sound even better ( growl )

 

[ffffanman]

I gave one of my gutted stock mufflers to my fabricator to use as a template for a Flowmaster and he left town and I never seen my sample back again.
The other one I cut open is beside my garage and I haven't used it for sometime.
The Flowmaster is on my car permanent.
Its a lower V-8 sound that I love.
People behind me dont really enjoy all the noise but hey, they can stay at home.
I bought a GTLW and used it only a short period of time cause I don't like the higher pitch sound, not into rice rocket sound.
Everyone else liked it though.
I sold it to a guy in Victoria.
Dan said a few weeks ago as as I passed him at 240kmh and 8000 rpm that my car sounded like a jet fighter.
Hi boost whipple with top speed headers and prospeed high flow cats and flowmaster.
I'm set then.
Have fun guys
Trev