Another Exhaust Thread :)
 

So I'm doing research on exhausts (I need to alter/change mine) and came across this. Might prove worthwhile to those thinking about changing their own.

Consequently I'm looking at changing my exhaust by removing the y-pipe (my exhaust is not stock) and inserting a single inlet dual outlet chambered muffler to two large offset inlet outlet circular mufflers in the stock location. This should prove interesting :)

http://www.pontiacstreetperformance....p/exhaust.html
http://www.pontiacstreetperformance..../exhaust2.html

Although those deal with piston engined cars, their information is still nice to have.

Furthermore anyone who has experience with exhausts please feel free to post.

Chambered mufflers are a waste of time if you're looking for performance.


-Ted

In my case performance has to take a back seat to daily ability/what won't get me in trouble with LEO's.

I still aim to have around 400HP with my setup, but I would like it to be as quiet if not quieter than stock (I know I'm asking for the impossible)

Would like to see the results when youre done & your impressions on how it sounds.

rotary + flowmaster = WAT

im also curious about sound lol.

Who said anything about Flowmaster?

Not going to be possible, unless we're talking about something super complicated which implies super expensive...

Ever seen a Ferrari exhaust?
It's basically one big muffler from engine to tailpipe!

Chambered mufflers choke off too much performance - you'd need to build a 600hp engine to get 400hp after choking it off with all the chambered mufflers.

You want quiet?
Just don't rev over 2,000RPM.
You thinking you can rev up to redline past law enforcement?
I doubt stock is going to prevent you from getting looks.

You own a PERFORMANCE vehicle.
It's sad that you're putting noise supression a priority over performance... :(


-Ted

I did a lot of research a while back on mufflers. Then "tested" a few out. This is the ONLY muffler I will use from now on...


Where to buy it...

http://www.jegs.com/i/Hushpower/526/13516101/10002/-1



Info...

http://www.hushpower.com/technology.php


Here's how it looks on the car...


http://i282.photobucket.com/albums/k.../Blackoutc.jpg

http://i282.photobucket.com/albums/k...wermuffler.jpg




Your welcome.

I have my doubts on anything Flowmaster makes...

I don't like that Hushpower muffler because we've messed with perforated cone disrupters before...they don't work.

I still believe a perforated offset pipe muffler will outflow almost any other muffler out there while giving you the best noise supression versus performance, period.

Anything baffled impedes flow - common sense.
The Hushpower muffler articles go into a lot of bullsh*t marketing words but where's the chart with the numbers?


-Ted

just make it loud :) apex n1!

Not necessarily :reddevil:
There's a thought!
No, but there are times I can not avoid going past 2000RPM in front of a LEO (see below)
It is, but I have to do what I have to do. VA is notorious when it comes to exhaust systems. I have thus far received two exhaust tickets in my lifetime in Northern Virginia. 1 was on the stock exhaust and was a "defective exhaust" never mind it was completely stock without issue, I still got a ticket. The 2 was when I was driving up hill and could not maintain 2000RPM while not impeding traffic. It most certainly is a catch 22 if you ever need an example of one.

Ted, it appears I'm getting conflicting information between you and NoDOHC. This is what he has to say in a similar thread:

Got an Iphone/smartphone? Got a db reader? Care to make a recording so we can get some numbers with it?

I do have a smart phone. But don't have a DB reader on it. Even if i did, i dropped it enough to where the speaker barely works on it. So i wouldn't trust the sound recorder on it.

I will say this. I had a 2.5" exhaust with a resonater right after the down pipe and a 2.5" muffler. I then built this exhaust which is 3" the entire way with no resonator, and this muffler is 3" also. And this exhaust is far deeper and much quieter.

No I don't have any hard numbers with charts to prove. But out of the 20 something mufflers I had on FC's. I would choose this one any day.

Nah, not really...

I'll put money that a perforated tube muffler will outflow any chambered muffler when it comes to performance, period.

Sure, the chambered muffler will minimize noise - that's it's primary design criteria.

I'm arguing performance versus noise suppression.

There's two ways to suppress noise from the exhaust - choke the crap out of it or "tune" by resonance.
Resonance tuning is a lost art, and does exactly what NoDOHC mentions above.
The problem is that you cannot tune the entire RPM band out - you can only quiet RPM ranges, which can sometimes be quite narrow.
So unless you find an experienced exhaust guy that knows the car's set-up, it becomes an expensive proposition of experiementing with muffler positions to get what you want.

I always say to just stuff the biggest, honkin' muffler you can affort and fit under the car to get the best suppression.


-Ted

Hey could you give me more information about this tune by resonance? its sound interesting. please?

It's pretty straight forward. You tune your exhaust by the frequency of the RPM band. For instance you can tune it by Exhaust length, mufflers--both in dimensions, and number, as well as configuration.

This kind resonance is for all intents and purposes deconstruction wave interference. If you're only using pipes you get the phenomenon only at modes of certain frequencies; ie 2000, 4000, 8000 rpm. When you begin adding in mufflers, pre-silencers/resonators, you begin to affect the wave pattern throughout the exhaust system. Now since we can't have a modifying length of the exhaust to minimize the entire rpm band you make compromises. You can have the exhaust be relatively quiet below say 3000RPM then it can get progressively louder before hitting another node and becoming quiet again.

At the end of the day one can utilize Fourier transforms to locate and eventually eliminate the peak 'oscillation' or waves and all harmonics there of. I would attempt to tune my exhaust using this method but it may just be an attempt in futility because I'm lacking the time to do it.

My exhaust is pretty quiet while cruising and sounds good at WOT. I drove 3 hrs out to PA with my buddy with the windows and sunroof open and we had no trouble shooting the shit the whole way out.

Magnaflow 3" in 2x2.5" out. 2.5" cans both sides. Turbo's make good mufflers too, add another ;)

I've got a few vids on youtube if you're interested in hearing her.

Ted is right, it is difficult to attenuate all frequencies with a chambered muffler.

I work with constant-speed engines, so for me, resonance tuning works really well.

I have never seen a production car muffler that works over the entire frequency spectrum.

A turbocharger is the closest thing you will get :).

Still the thread that I posted explains the basic functionality, so you can pick a few mufflers to optimize attenuation without destroying performance.

The post was meant to answer the series/parallel question and the modeling of the exhaust system. Not as an exhaust selection guide.

In this case of actual performance of available options, I would defer to ReTed - experience trumps theory 100% of the time.

I will still argue that a carefully designed exhaust system could make minimal backpressure and still effectively attenuate the sound. As I pointed out in the technical section, sound attenuation does not have to cause backpressure (attenuating the AC does not effect the DC).

I think you either need to fight the ticket and stick it up the officers ass, or MOVE.
You should NOT be getting tickets for a stock exhaust - that's just ridiculous.
You just cannot go quieter than stock and expect to hit 400hp...
That's next to impossible.


-Ted

I know Ted. I know. But that's how the law is in VA. It basically boils down to if the Officer thinks it's illegal it's illegal. It would take a lot to fight an exhaust ticket in this state.

I'm thinking of these for the mufflers, thoughts, or should I look at a different one?
http://www.racingbeat.com/Mazda-Perf...rtNumber=16025

Ignore the turbo seal that's going out and focus on the BOV and the whine of the drums. It'll give you a good indication how loud it really is. I've never been bothered and I CRUISED by a VA leo who pulled over a ticketed a certain Red FB with a streetported 13B with a full RB exhaust on the way back from Deals '09

I see a white box?

TTT, when you do a youtube tag you only copy the stuff after the "="

I wish you had db numbers with it--not that I don't believe you, but your exhaust sounds somewhat 'harsh' but that might be because of the microphone on the camera or a number of other reasons.

Another tip to quiet down the exhaust...
Run a downturn tip on the muffler.
Not the best looking if you're into that monster exhaust tip, but we are talking practical, right? :)


-Ted

Whoops, thanks.

I don't have a db meter or I wold use it.
It does sound harsh, it's a $130 camera.
I'll grab the GoPro on saturday when I'm back

:rofl: As you can see, I hate that whole monster tip BS anyway. Those are ~3" tip I think? Summit Racing too.... I had a problem spending more on a tip than I spent on the cans... go figure right?

Vex, why not an electric cut out? Off the DP put the cut out. One 3 or 3.5 goes through a few baffeld mufflers to keep shit quiet, and the other heads off to a strait thru design? There's enough room under the FC to get 2 3" pipes there and the provisions are already there in the bumper. Why not?

Just looking for the easiest route right now. For the most part I'll redo it when I have the $$$. But as it stands to quiet it down it would only cost me about 350 max. If I do a cut out it would be an extra 100+ all the other pipes and stuff to make it work which isn't in the cards right now. That's all.

Does anyone have any say on the racing beat mufflers I listed? Are those going to be too loud? Should I kill performance and go with the chambered muffleres--though with the simple test I did with a friend over at his place, chambered muffler seemed to amplify the idle exhaust note...

I figured I'd share this with you guys for others benefit: I emailed Flowmaster and they sent me this:
I appreciate their honesty about it. So I suppose this leaves just rotary specific mufflers to consider....

Cut out is really the only way to have best of both worlds. But i wouldn't run it all the way back adding un-needed weight. Place the cut out right on or after the downpipe. No cost at all really. Just a spare 3" pipe with a flange. Another flange to block it off and 2 or 3 bolts. Done... would cost only about 10-15 bucks extra and will weight maybe 1lb. Only down fall is unbolting it, which takes all of 10 seconds...

I will say that's good of them to not give you bad info trying to sell the product.

would be more expensive, but could always get an electronic cut out. This would allow an easy change over on the go. I think QTP made nice cut outs.
http://t1.gstatic.com/images?q=tbn:A...NlY3BAeLZnEOI=

I had another thought on my commute this morning (I know it's dangerous). I have functional perforated tube mufflers that are still functional. What if instead of using regular old tubing to go from the y-pipe portion of the muffler I use these rather 'small' mufflers instead. I see the benefit two fold:
1) I save money by not buying additional stainless steel tube
2) I get a quieter note because they have muffeling capability

Basically I'm doing what Ted suggested about ferrari and making a huge muffler :).

In addition to this though what if I combined a diffuser and a muffler together? Have a large perferated tube design feed into a rather flat but large muffler filled with stainless steel wool and outputs into two exhaust mufflers on the side in the normal location.

Thoughts? (I want to see if anyone can spot the issue with the latter idea :))

T, the RB mufflers are the best for the rotary IMO. I have been using them for years with fair success in accomplishing what you are trying to do......quiet without losing too much performance. I have had to modify a few RB pre-silencers to fit in limited areas and was able to see the internals, which is as Ted mentions...perforated and offset with a bunch of curly stainless noise suppression material.

You may want to also consider a heavier wall thickness if you purchase tubing...this takes out a good bit of the "metallic" sound in the rotary exhaust.

On a different note, I will shoot you a PM soon about seeing if you can help me with a intake plenum design for a sidedraft Weber (DCOE).

Todd B.
(formerly of No Limit Industires in Alabama)

Is this their normal/self branded mufflers or their universal mufflers they offer?
Sounds like a plan.

This is exactly what we're going to do with our 20B project...

Magnaflow center 4" in, dual 3" out
...into...
twin 3" in / 3" out offset mufflers in the back

It should to pretty good noise suppression.


-Ted

Will you have to worry about the gas tank in the stock location? AKA if you're running hot you'll heat the gas in the stock location and if there's an accident...?

Dunno, but good question...

The owner of the car is doing all the fab'ing on that exhaust.
He's the certified weldor.

The layout sorta mimics the Racing Beat / RS*R FC turbo exhaust, with the exception of the center muffler.
We're hoping that center muffler will help quiet things down.

We were running a 4" in / out center muffler, but it was still too loud.
We've gotten warnings here in Hawaii for exhaust noise - kinda rare, so it's pretty loud.


-Ted

hmmm.... Interesting thought. Let me know how it turns out. I may potentially do a similar route when I'm in a house.

Their normal mufflers/pre-silencers that are included with their systems. I have never used one of their universal mufflers.

I am trying something a little different on the current system. I will be using a Vibrant stainless pre silencer to see if it holds up like the RB units. It costs about $100 less than the RB and stated that it was for higher temps than standard mufflers. I have a feeling that within the first few thousand miles, the sound deadening material (even though it is stainless similar to the RB) will be burned out and I will have a hollow resonator.

Nice, that's my exact setup with a different sizes

I've used the vibrant tubing in my exhausts. Holds up quite well. Can't speak about their muffles though.

Just out of curiosity where is everyone finding these offset mufflers they're talking about? Everyone I've looked at doesn't seem like it would hold up. I'm half tempted to lay down some real coin and buy the RB y-pipe and mufflers.