zyounker, how come you count the restriction of having a y-pipe installed, but you don't count the relative restriction of one muffler instead of two?

The y pipe is a restriction itself, however once past the Y, the dual system outflows the single greatly! There are restrictions in both, however, going by FPrep2ndGenRX7's example, the dual will outflow the single.

You seem really fixated on the Y, and are misssing the grande scheme of things. As NZ said, restriction is cumulative.

Nima

 

So how come you're having such a hard time understanding it? Uh, yeah we do...

 

My opinion. 2 looks better. Maybe if you fill in the 2nd cut out single will look fine. But I think Dual looks better.
Personally, I'd even consider going with a single, and have a fake 2nd (may be ricey, but looks better than 1 tip).

 

Is there a point in arguing whether a single flows more a dual? The point is what makes more power on our cars. I mean a 4 inch system will outflow a 3inch system, but the 4 inch will probably result in a loss of midrange power with no increase in topend. So what's the point. I think the duals look a bit silly, when you know there's no real reason for them (except for maybe allowing a bit more flow for for a given exhaust volume), but the rx7 is a sports car, isn't it? I've got a single and love it. My car is loud and obnoxious, yes, but so has every other rotary i've owned, I like it.

Mat.

 

You answered your own question. "A bit more flow" with the added benefit of a quiter exhaust(two mufflers as opposed to one). I prefer an exhaust that is quite under normal driving but can get a little loud at WOT and higher rpm's. I'm older than most on the forum so my version of quiter is probably almost silent to some of the younger forum members.

 

When using a straight through 3" muffler on a 3" exhaust without a change in diameter is less of a restricion then a 3 inch exhaust with a Y and 2 mufflers. it is that simple. The dual muffler will not be much different, but will be a little more quite.

So NZ.. Show how a pipe with out any change in diamiter will flow less then one of the same diamiter with a Y???? As long as you don't have a baffled muffler, the single will flow better. if you have a very restrictive muffler, then the dual will be equal, and possibly even flow more if the muffler is really bad.



This is getting old....

 

I have said REPEATEDLY that you would have to use a straight through muffler on the single exhaust..

And a straight through muffler will be less of a restriction then the Y..

And you can use that same muffler on the dual system, but it will still not flow more. because the velocity of the exhaust gasses have already slowed down.


-Zach

 

You don't seem to be able to grasp this simple idea. Once again, in case you missed it the first time, two 2.5" pipes have considerably less restriction than a single 3" flowing the same volume (about one third less in fact), and even though some of that advantage is lost in the Y, the nett result is a system with less restriction. Please tell me which bit of that is giving you trouble, and I'll explain it. The restriction of the actual pipe itself is just as significant as any bends or fittings. The smaller the pipe is, the harder you have to push it to get the same flow. If you send half of the volume though a pipe with more than half of the original pipe's area, the restriction caused by the pipes is less. Common sense. So? I'd only use straight-through mufflers in a dual system anyway, so this point is irrelevant. This statement doesn't make any engineering sense, and along with others you've made prove your knowledge of fluid dynamics has some holes. If you're going to argue this hard about something, you should at least have a bit of subject knowledge to back up your "facts".

 

damn the bickering goes on.. same pointes restates hehe

so.. who wants to fund a little research and they can flow bench two exhausts to see which flows better

 

Yes, quite tiring..

Anyway, look at almost ANY japanese tuner, what do they run? singles
what exhausts make the most top end power? singles.
which one is better? up to the owner


BTW NZ, so do you have any proof? other then ramblings? because in the past i have looked at plenty of dyno sheets and the singles with free flow mufflers made more power. but often had less lowend torque. I really don't feel like finding all of them again, cause i don't really care what you people do.

-Zach

 

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What all the hub-bub about exhaust backpressure? I thought I read somewhere that backpressure is irrelevant and it doesn't matter how big an exhaust pipe you use and that bigger is better.

Sam Strano (strano@ncentral.com)
Not entirely correct. I agree that backpressure isn't relevant; the less the better. The hitch is that pipe sizing is very important to the flow of the system. The bigger the pipe is the less pressure is there, however if the pipe is too big for the amount of air an engine can move, you'll lose power, even though there isn't any backpressure. If you run a 3 inch system on the car, the velocity of the exhaust gases is going too slow down, because the gases have to expand to fill the pipe. And slowing down the exhaust obviously isn't what you want.

 

from all my fun searching on google i've found a few things.

dual vs single. dual requires smaller diameter.. say if you had 2.5" single.. you'ld need 2.25" dual to flow the same.

So from what I found.. Dual will out flow a Single and not require as large of diameter. but an equal size dual could rob the motor of power over a single. this is probalby why you find 3" single and 2.5" dual because they do the same job.

 

That is true, but a 3" on a 13BT is suppose to be the optimal size for top end power. Although I have not done any testing or checked, that is just what i have read.

The other thing to think about is as the gasses cool toward the end of the exhaust you need less flow. In theory you could gradually get smaller in diamiter without effecting flow in a negative way. That is also why i believe that a Y pipe is a restriction, but having more flow after the Y does not really help.


-Zach

 

bump dual there are so plaid out. i like the flames from a single better

 

well did th is thing get diged up or what

 

GIR!, you will do what pleases Postulio!

 

Single exhaust is the only way I would have a car. But that's because I'm all about performance. Better flow, less weight, less cost, etc!

Since you are only concerned with the looks though.. I'll have to vote you go dual!

 

I AM SO TIRED OF SEEING THIS THREAD PLEASE RETIRE IT NOW!

 

I have gone single exhaust, does anybody know if someone makes a
rear skirt or bumper with only one "exit"

 

Yeah. It's called BONDO!

 

Are we still talking about this?

What the dilly, yo?

If you want the bling, get the DUALS.

If you want the speed, get the SINGLE.

and who cares about an empty cutout? its called "FUNCTION OVER FORM" if it gets the job done, dont question it...

 

yes I think duals look better, yet I went with single. Function over form.

BTW....this thread will never die

 

damn i cant believe thers 7 pages on if a dual exhuast or a single looks better. wow. haha

 

I run an Apexi N1 single side exhaust and it looks just fine. I'm more into function over form and the single side will put down more power with less weight than a duel setup.


Picture from the rear of single sided N1

 

I dont know if anyone has mentioned this, but there actually is a functional reason for having the dual exhaust setup on an FC, other than looks. It turns out that having a single exhaust that splits into two halfway actually reduces noise over a single setup. This is also described in the Racing Beat catalog. Perhaps Mazda could not get the noise/flow levels at the right balance with a single setup, and chose this setup instead? Who knows.

Anyway, as far as my opinion goes, I like the looks of a dual. I especially like the looks of the N1 dual, and would like it if corksport would make something like this. I guess HKS does, but it is probably as expensive as the N1 dual.