RotaDrift

I was thinking of buying a cat back but am on a budget. I noticed corksport's insanely cheap exhaust. I was wondering the benefits,if any, in going with a single exit exhaust system instead of a dual. Also does anyone have any movies or sound clips of a second gen with a corksport cat back?

DeclareYrWar

hey, the main advantage of using a single exit exhaust is weight. corksport is a great exhaust from what i understand (i have racing beat cat back myself) which surprised me considering how inexpensive it is as you said. there are some video clips of a corksport cat back here: http://videos.streetfire.net/search/corksport/0.htm

NZConvertible

Weight is not the main advantage. The weight savings over a dual muffler system of similar construction is well under 1% of the car's total weight, i.e. you'd have trouble measuring any performance difference let alone noticing it.

The main advantage of a single muffler exhaust is cost, that's all.

RotaDrift

on their web site it says it shaves off 36 lbs. At 289 plus shipping it doesn't look to bad. I just thought there might be some back pressure issues with dropping the second muffler.

NZConvertible

That's 36lbs compared to the stock exhaust. The weight difference compared to an aftermarket dual-muffler exhaust will be about half that.

classicauto

iTrader: (3)

the other benefit is less turbulent exhaust flow...now this is a very minor and nearly moot point, but nonetheless it exists.

The dual systems on most of the setups for these cars are split Y pipes, since the exhaust has to get pushed through either way, it will end up favouring whichever side flows a tad better, meaning that any flow trickling out the marginally more resrictive side will be more turbulent and have less velocity.

The single doesn't suffer from this, so long as the system is large enough to support what your running a single is better than a dual IMHO.

NZConvertible

This is clutching at straws a bit. The system is symmetrical so unless the system is very pooly made, the flow through each branch should be equal. Any difference would be so small that it's not even worth mentioning, and even if there was a difference this would not cause turbulance. How would it? This is a non-existent "problem".

And exhaust gases do not "trickle"...

classicauto

iTrader: (3)

yes I realize its clutching at straws a bit which is why I said the point is nearly moot.

My justification behind this comes from a loosely scientific test I did a while back...

On a 2.5" straight pipe (with cat) to 2-2.5" pipes at the Y, I found that at idle both tips would puff equal breathes of exhaust...however, under load, the left tip would be puking ehaust while the right would have approx. half that (as I said loosely scientific, we hung paper over the tips - go ahead and laugh but if you saw the actual test you would have noticed the same thing)

Now its very flawed becuase this wasn't a racing beat system or anything like that - it was custom made, but anyone who would look at the system would say both sides SHOULD flow equally......but it wasn't the case under load.

Nonetheless I can't see it affecting performance to any measurable degree but I still stand by my opinion on an adequately sized single being slightly better for overall exhaust velocity and flow.....if nothing else the fact that the exhaust flow has to make an extra turn on the dual system in comparison to the single would suggest a mootly different amount of flow.

tarmac_terror

I'm also looking at upgrading to a single exit exhaust system and sorry NZ, but I tend to disagree on the weight issue... For example, I can tell the difference in the way the car feels when I'm driving on an empty or full tank or if I have a passenger... What do you believe is a reasonable reduction in weight before the effects can be noticed/measured?

I guess what I'm trying to say is that if your overall goal is to increase the power to weight ratio, all these small things add up little by little in the end.

NZConvertible

Even if one side really was flowing twice as much as the other (doubtful), this could only be because one side was built completely differently to the other or a large restriction was present on one side only, which is why I said "unless the system is very poorly made".

Did you know that for the same flow two 2.5" pipes cause about 30% less restriction than one 3" pipe, but one 3.5" pipe causes about 35% less restriction than those same 2.5" pipes? Whatever size you consider adequate for a one pipe, I can suggest a pipe size that will outflow it using two, and then you could suggest an even bigger single pipe size again. It's a pointless exercise. The fact is it's not the muffler configuration (i.e. single or dual) that determines how well a system flows; it's the size of the pipes and how it's put together. It's nonsense to say "single flows better" or "dual flows better" because there are far too many other more important variables.

There is no extra turn in a dual system. The pipes follow exactly the same path a single would. If both sides are symmetrical, both sides provide the same restriction to flow.

So you should. 60L of gas (leaving a safe 10L in the tank) weighs 45kg (100lb). An adult passenger weighs anything from 60kg (130lb), probably a lot more. The weight difference we're talking about here is less than 10kg. Totally different ballpark.

That'll vary depending on the person, the car and the type of driving. I can just notice the difference when I put ~40kg of fuel in my ~1350kg vert, about a 3% increase. I'm positive I'd never notice a 0.6-0.7% weight savings from a single exhaust.

edomund

I have the 80mm turboback corksport exhaust. It is a very well made piece with great welds, it is nice and cheap. It performs very well and makes power.

The downside of a single exhaust with no resonator is it's freakin loud!

I had to put in a ECV from Apexi so I could control the loudness. I can post a sound clip tomorrow maybe.

aram

iTrader: (1)

if you own a FC 15#'s of saved weight is a lot!

Wh1t3 C0m3t

I like the single better, I had a custom single on my NA, and will got w/ the Apexi N1 single for my turbo. The single looks better imo, is lighter (even if only by a little) and doesn't have the back pressure at the y pipe like a dual would, I'm not saying one side would flow more or be unbalanced I'm saying especially for a turbo the less back pressure the better. the exhaust gas will cause some bp when it gets to that y. the sigle only has one way for it to flow. most things want to take the path of least resistance, which wwould be single. If its an NA particularly an s4 you want a little bp or you lose power. an s4 need some bp to activate the 5 and 6 ports. I had single catback on my s5 na that was 2.5 inch and it was good, not too big that it lost power and since 5 and 6 are opened by the air pump i didn't have to worry about bp.

classicauto

iTrader: (3)

No it doesn't, a single (how I design mine) goes from the turbo - right side of the car - straight back to the left corner of the vehicle. A dual system would go from the turbo to the front of the rear subframe in the center of the car and then make two 35 degree turns (in the form of a Y) and go to each corresponding side of the vehcile.........and THAT is the same shape? I don't quite understand that.

oakback

Is everyone ignoring this, and trying to come up with reasons why single is better? Seriously, I bet the #1 limiting factor for most FC owners is cost. Good enough reason for me to go single (which I did).

Cold Dark Shadow

lol you know i was thinkin about what exhaust to pick up on the cheap and that seems to be a good one lol, wish it was dual but i can live with single

socalrotor

iTrader: (1)

corksport is INSANELLY LOUD. I have a single and it is loud as **** too but the uncorksport is the loudest I have heard. If you do get it, just to let you know the silencer is a PITA. My bro blew his out more than a few times, before it MELTED. But it does keep it quiter while it lasts.

NZConvertible

The restriction caused by a Y is hugely overstated by people who simply don't understand fluid dynamics. Unless it's a hack job, the small amount of restriction caused by a Y is offset by the lower restriction of the two downstream pipes (assuming they're sized correctly). This is a very simple engineering concept that a bunch of people seem to have a lot of trouble understanding.

A properly made Y goes not make two 35deg turns. Now you're just making **** up. Most single systems run straight back and then have a bend towards the exit side. A dual system follows the same path as a single until it splits and then the two sides can be made symmetrical. No extra bends!

That seems to be common theme in this topic...

VashtheStampede

to ask a different question,

would dual mufflers allow for more sound dampening at an equal flow rate?
i mean, if you have a single exhaust that flows so much, can you split it into a dual exit setup an use the reduced flow rate ( velocity or mass, whatever) through each individual muffler to reduce exhaust noise?

or is this not even a reasonable guess?

Wh1t3 C0m3t

I know its not a big difference at all , most wouldn't even notice it, but to those that are hard core every little bit helps, I don't plan on making insane power so my choice for single is just preference. It depends on what the car will be. ie- turbo, na, dd, drag, drift, street, etc.

7 freak

i got a friend who have dual exhaust with 2 super turbo mufflers and dons't sound load and does are ship!

NZConvertible

Absolutely, that's the main advantage of a dual system. two mufflers in parallel only have half the sound energy to deal with, so are more effective at quietening the exhaust down. This is a huge advantage on a street car, particularly since exhaust noise enforcement is getting tougher all the time. I laugh when I see cars driving around with flow-killing butt plugs in the exhaust tip because without it's too loud without it.

You still just don't get it. Did you not read the numbers I posted above? You still think single always flows better. You need to get that dumb idea out of your head. If you prefer single that's fine. Just admit that you prefer the way it looks instead of using dodgy engineering to convince yourself it's better.

Don't see how it makes all that much difference for a street-driven car actually, turbo'd or not. Pure race cars have totally different design considerations, like a lot less total weight, far less strict noise limits and no need to even exit at the rear. And since when does drifting require a particular type of exhaust?