Hey folks, as some of you know I'm currently in the process of building a large single turbo'd Z. We played around with a few ideas on my old Fujitsubo exhaust, namely a boost actuated exhaust cutout, and found it to be a pain to deal with.

What we've decided to do is a custom 3" turbo back exhaust. I'll start off saying I've got a 3" downpipe from the turbo, so we're limited to that size for the most part right off the downpipe. Next, I want a high flowing exhaust, but also don't want it to sound like a drag car every time I fire it up, so a resonator is a must. I'm not a big fan of single exit exhausts, so I want it to split to two mufflers/tips. Also, I want the mufflers to have nice classy look and to... actually muffle the exhaust.

So, I've come up with the idea below. Maybe some of you exhaust experts can tell me if my plan is sound.

I'm looking at an "ultra quiet resonator from Vibrant Performance. I wanted to bolt it directly up to the flange that comes off the downpipe, so basically it will extend the 3" section of the exhaust. Here's the resonator:
http://vibrantperformance.com/catalo...5cdca11ce94a14

-- Question for the exhaust gurus. Does anyone know if doubling up and running two resonators will further deaden the drone of the exhaust? These are only 14" each, and if I run two I could have a total of 28" of resonated pipe. I'm really interested in thoughts on this.

Next, I want to run a 3.5" pipe off the back of the resonator. I was thinking this may help flow slightly and assist in a "scavenging" effect by opening up the exhaust a little.

The 3.5" pipe will split up into two 3" pipes, which will attach to the two 3" inlet/4" tip straight through mufflers. I want these to be straight (not angled), and I'd like to have a classy looking exit. I think my rear bumper will help with this because it covers the canisters well.

Here are my options for mufflers. While I REALLY like the Ti tip of the barrel type canisters, they always seemed a bit "ricey" to me after seeing every riced out civic rolling around with them. For that reason I'm also considering a larger more traditional type muffler with a rolled 3" SS tip. The larger muffler might also help in making the exhaust note quieter. I like the Vibrant tips because all of them have the option of an angled tip.

Here are the mufflers I'm currently considering. If anyone has experience with these and how they compare sound wise, please let me know:


http://vibrantperformance.com/catalo...5cdca11ce94a14
(does anyone know if carbon actually SOUNDS different? I could care less how it looks...)


http://vibrantperformance.com/catalo...5cdca11ce94a14


http://vibrantperformance.com/catalo...5cdca11ce94a14


http://www.racinglab.com/5zigfir3turp.html



Below is a ms paint drawring of what I'm planning. It's extremely simple, but I thought would be easy to understand for the non-reading types here.

So... ideas? Any EXPERIENCED advice would be appreciated.

 

Love the pic. GL

 

I made a custom exhaust with the second Vibrant muffler you posted. it looks fantastic and the sound is great from the vibrant.

the only thing I could give my opinion on is make sure the fabricator is excellent. the better the fabricator the better the exhaust.

mine follows a similar path but reversed from yours (NA to single exit) and I put two resonators in-line just like you did.

I was told that merging or splitting the exhaust far back makes the exhaust louder though.

 

Thanks for the input. So in your opinion two inline resonators followed by an immediate split would be
best?

Edit - I just saw you said "second muffler"

 

1062T if I remember. for a single I think it was a little too short in hindsight, but it's the same length as the JIC (I measured 17 inches tip to back of can). AAM uses the next one at 23 inches in thier single (part#1059 i think). the 'T' in the part number denotes the Titanium tip version of thier mufflers. I don't like the carbon wrapped ones and went with a straight cut tip.

this place had the cheapest price online: http://stores.channeladvisor.com/ver...et%20Mufflers/

Inlet: 3"
Tip Size: 4" O.D.
Tip Style: Straight Cut, Titanium
Dimensions: 6.25" O.D. x 17" Long
Material: 304 Stainless Steel
Weight: 6.5 lbs
Part#: 1062T

in regards to the path, I can't say, since your exhaust is sort of opposite to what I did. In my case it made the car undriveable(the merge, not the resonators), causing throttle fluctuations and was really, really loud. the two resonators worked great to tame it.

IIRC, Fast intentions gave me the advice to run two smaller resonators side by side and seperate, then merge the exhaust gases again. so it would look like:

turbo ---<=>-< mufflers (my picture of your exhaust before split to mufflers)

 

just as a note: I liked the vibrants because they are a straight through design like, I can stick my hand through it.

do you want dual mufflers just for the look? I am a fan of the stock type canister for dual exhuast.

why do you think cutouts are a bad idea? they do offer electric ones...

 

Good info, thanks for the link!

I've thought about running two side-by-side resonators, but I want to avoid merging the exhaust stream after it's seperated. I don't think that pushing two 3" pipes into a single 3" or 3.5" would be best with expansion/etc.

If I could squeeze two side-by-side resonators in there and just keep it split all the way to the rear I think that would work better. I'm not sure how effective it would be to put the resonators further back on the exhaust closer to the mufflers... hmm...

 

That's a big reason why I like the vibrant mufflers too. They look really nice and high quality as well.

Yes, I prefer the dual muffler look. I'm not a fan of having an open hole on my back bumper.

We played around with a boost contolled cutout on my car but Jeremy said that he would have a hard time tuning with it. I prefer to not have an electronic cutout that I have to be stopped to open and is prone to failure of the electric motor. The original idea was to set an MBC on my boost actived cutout to open up at 11psi so it would only dump on my mid-high boost maps. Apparently it caused some weird issues with boost fluctuation so we scrapped the idea.

 

I'm going to make a custom tray diffuser to fill that hole. or run a differential cooler just need to finish up some other stuff first.

that is what I would worry about (again, don't know if this applies to a turbo exhuast) but because the split near the back caused the fluctuations in my car, I would worry the same for you, it must've been messing with backpressure or something.

edit: another idea we had (my car club friends) was to swain or jethot coat the piping, maybe only to a certain point to keep the thermal expansion down and keep the velocity up as long as possible. it would increase weight and I heard the jethot is prone to flaking off unless you buy thier topline stuff.

 

Stillen mufflers and dual wall tips FTW

 

I'm thinking the split on from a single to dual would be totally fine on the turbo exhaust. The surface area of two 3" pipes is definitely a lot more than the single 3", so backpressure will not be an issue. As far as merging two pipes, I see where they're coming from when it comes to a y-pipe. That would be a killer on a turbo setup that requires no backpressure, unless you were able to step it up from dual 3" pipes to say a single 5" pipe.

The only single exit exhaust I thought looked good exiting really was a guy that had his car at PF from miami. He had a greddy rear lip with a single exhaust and the other hole had a fabricated fiberglass piece that fit smoothly in the gap.

As far as the high temp coating goes, it's a decent thought but I'm not willing to split hairs to that level. When you're talking about moving 700hp worth of air I think the very small difference in flow the coating MAY provide would not be worth the expense.


Heading out of work now... thanks for all the input so far!

 

I built my exhaust, its a 3" single with Hks ti muffler, and 1 Silverline 18" resonator, the car isnt loud or drone at all. 2 14" resonator might be too much imo, on top of the two mufflers. Im not sure what your tastes are tho.

 

it would be crazy if this thing ended up being as quiet as a stock Z with some outrageous amount of HP

 

Yes but the resonators I'm using are a straight through design that involves just a perforated inner pipe with packing material. I think two resonators would actually get it to the level where I wanted it. That is, if they worked much better than a single resonator.

One person's idea of "loud" greatly differs from anothers. If you heard what my car sounded like before this build then you'd understand what I'm after.

I'd like to come as close to that as possible. Of course it has open dumps so it'll get loud, but I'd rather make it as quiet as possible at idle and while cruising out of boost.

 

I guess one of my main questions is how the difference between these two styles of mufflers would effect sound levels:




I assume the smaller canister would generally be louder, and the larger would tend to muffle the exhaust tone more. They're both a straight-through design, the only real difference is in the amount of sound deadening packing inside the canister.

I like the TI tips. Unfortunately the only rolled tip muffler like that with Ti tips that I've seen is on the greddy evo tt.

Anyone agree with these thoughts?

 

lol @ the pic. i admire your attention to detail.. the jdm mufflers and all. haha gl.

 

It would look better with the apexi...

 

Only thing I'm really concerned about the Apexi muffler is that the canister might actually be too big to fit back there. They make left/right exit ones but the only 3" inlet 4" tip versions I can find are center exit.

As of now I'm leaning toward the two I compared above. I just wish I could hear how both sounded.

 

I never knew that those canister type mufflers were straight through. i figured they were all baffled, hence thier shape.

I also never though that style looked right on a Z... I think blitz nur spec looks like that, and obviously the evo-TT and it's just a weird shape for the way our bumpers are shaped.

tips on those mufflers are interchangable/adjustable for length, no? If they are held on by a screw maybe you could buy a tip seperatly.

(I like single wall)

 

you could always go with the muffler you want and then buy tips you like and have them welded on (as long as they aren't TI)