"Grindintosecond" (Grindintosecond)
04/30/2015 at 21:51 • Filed to: None | 1 | 22 |
Why? This occurred to me after walking in to the grocery store today, an STI with custom exhaust rolled by looking for parking. I could hear it’s barely muffled turbo just lightly spinning over. It hit me. With one single turbo exiting through one pipe, why does it need two mufflers and four pipes? I hate vanity appearance packages. I like the properly purposeful solution. One turbo, therefore one single pipe from it and one muffler and one pipe out. Less waste, less weight, proper tuning. Done.
I’m becoming that old cranky man on the porch yelling at the kids to get off of his lawn aren’t I?
TheOnelectronic
> Grindintosecond
04/30/2015 at 21:53 | 1 |
Well, the mufflers theoretically provide more restriction than the pipe alone, so one pipe with two, parallel mufflers makes sense.
daender
> Grindintosecond
04/30/2015 at 21:56 | 2 |
That puzzles me as well on Mazda Miatas.
Why does a NC Miata need dual-exit exhausts? Why can’t it be a simple and light like it’s supposed to be?
PS9
> Grindintosecond
04/30/2015 at 21:58 | 1 |
I’m becoming that old cranky man on the porch yelling at the kids to get off of his lawn aren’t I?
Yes.
jvirgs drives a Subaru
> Grindintosecond
04/30/2015 at 21:58 | 3 |
Mike
> Grindintosecond
04/30/2015 at 22:00 | 0 |
I’m all about simplicity, but I also obsess over symmetry, so dual-exit exhausts get a pass from me. Asymmetrical single-exit pipes actually really bug me.
Logansteno: Bought a VW?
> Grindintosecond
04/30/2015 at 22:01 | 0 |
Well, I see two reason: less restrictive to an extent, and better looking/symmetrical.
Though I do love me some dual tips on one side.
I don’t understand why normal sedans with little NA 4-pots need dual tips. Nissan is guilty of doing this, and so is Mazda that I can remember. My mom’s Fusion has dual tips, but only the 2.0T model has them, other Fusions have one pipe. I guess it gives a more sporty image to the car?
GTRZILLAR32-Now saving for Godzilla and a condo
> Grindintosecond
04/30/2015 at 22:06 | 1 |
Its probably purely for aesthetics...but the weight doesn’t matter much as the exhaust is close to the ground, unlike this Saab.
Also, a dual exhaust like the Subaru’s may help corner balance the car a bit...but that’s me purely speculating.
nFamousCJ - Keeper of Stringbean, Gengars and a Deezul
> Grindintosecond
04/30/2015 at 22:07 | 0 |
....Oops.
but it has been fixed..
Drakkon- Most Glorious and Upright Person of Genius
> Grindintosecond
04/30/2015 at 22:22 | 1 |
hate it. hate it hate it hate it.
One turbo, one tip. My Forester likes it that way. Sounds awesome, too
Nonster
> Grindintosecond
04/30/2015 at 22:34 | 0 |
This always bothers me. There is no real practical or performance based reason to have dual exhaust on a car with an inline engine or one with a single turbo. It’s not that bad on bigger more powerful luxury or performance sedans like BMW’s or Merc’s but it’s stupid on small 4 cylinder cars.
That Bastard Kurtis - An Attempt to Standardize My Username Across Platforms
> Grindintosecond
04/30/2015 at 22:37 | 0 |
Duals look funny on a Subaru to me. I've always kinda thought of it more according to the number of cylinders...6 or less gets a single from me, 8 or more gets duals. I never noticed I thought that was until just now, actually.
Opposite Locksmith
> Nonster
04/30/2015 at 22:48 | 0 |
Subarus are essentially banked
blacktruck18
> Grindintosecond
04/30/2015 at 23:49 | 0 |
My guess is symmetry. When the manufacturers design cars they put two exhaust cutouts in the bumper for “balance” or something.
BiTurbo228 - Dr Frankenstein of Spitfires
> Grindintosecond
05/01/2015 at 05:17 | 0 |
I don’t like this either. It’s excess weight which I really don’t like (don’t like sunroofs for the same reason).
As far as I can tell there’s no performance benefit either. In fact, they might hinder performance slightly.
That’s coming from a couple of experiments people have done on Triumph Spitfires and GT6s on the forum I’m on. There’s two main aftermarket exhaust types: big single silencer and twin-silencers (that actually end up being slightly wider combined than the single).
The big single makes more power than the twins. Probably because the y-pipe split creates turbulence and backpressure I’m thinking, or that with two smaller pipes there’s more of a turbulent boundary layer compared to the free-flowing air in the centre of the pipe.
random001
> Grindintosecond
05/01/2015 at 06:36 | 0 |
Technically, it can be used to great effect. Splitting the outflow into two mufflers allows those mufflers to be quiet, as mufflers are intended to be (root word "muffle") and yet since each only needs to handle half the exhaust gas the backpressure is much reduced vs. having a single muffler, unless said muffler was a) enormous, thus increasing weight, b) straight through and ineffective as a muffler or c) creating a lot of backpressure and reducing performance.
Also, symmetry.
uofime
> Grindintosecond
05/01/2015 at 10:46 | 0 |
Two good reasons for a design perspective
1. balancing NVH, performance and packaging requirements
2. appearance.
I suspect in the vast majority of cases its reason number 2
BoxerFanatic, troublesome iconoclast.
> Grindintosecond
05/01/2015 at 10:53 | 0 |
Usually exhausts like that allow for two mufflers that simultaneously can keep sound volume acceptably low, while each muffler has enough flow rate to handle half the total exhaust flow.
A single muffler has to be either free-flowing and less effective at sound attenuation, or if it is acceptably quiet, it usually impedes exhaust flow more, and creates more back pressure. Or the muffler has to be larger. weigh more, and take up more centralized space.
Grindintosecond
> BoxerFanatic, troublesome iconoclast.
05/01/2015 at 12:04 | 0 |
So, If I built a 1,000 hp engine, the noise would necessitate wither an enormous single can or eight smaller ones? Here’s one thousand HP out of a single muffler sound.
I can see the possibility of multiple mufflers being required to have the area to withstand the sheer exhaust pressure on overrun in this case. I do understand the theory behind your statement. I would say that any regular street tune WRX or turbo engine would work just fine with a single muffler, besides, the noise attenuation of the dual exhaust in my pic and from the car I saw yesterday is very very poor at best lending it to be a novelty design.
BoxerFanatic, troublesome iconoclast.
> Grindintosecond
05/01/2015 at 14:02 | 0 |
Keep in mind, turbochargers naturally attenuate some exhaust sound in the turbine, and prefer a free-flowing un-baffled muffler... A twin turbocharged narrow-firing-order inline 6 1000hp engine likely won’t be as loud as a 1000hp big-block V8 without them.
Any muffler with acoustic baffling or chambering, and a circuitous flow route inside the muffler would impart more back pressure in the system, especially if the catalyzers aren’t the bottle-neck, or have been removed. Two chambered mufflers can diffuse the flow volume, and alleviates some of the flow-speed-reduction effects, compared to just one chambered muffler trying to handle all of the flow, with the reduced velocity. A free-flow muffler, even just a single one, has less of a velocity reduction effect... and does much less of the sound attenuation.
On that Supra, or other turbocharged cars, the turbocharger does some of that as a byproduct anyway... Subarus with unequal length headers have their own pulse-frequency sound effects anyway... which some people actually miss now with equal-length FA20 and FA20DIT engines.
And yes, most exhaust systems, especially aftermarket, for mainstream cars do tend to have aesthetic and acoustic appeal design factors, rather than pure fluid-dynamics. Symmetrical tip appearance, and desired sound characteristics are a reason that aftermarket exhausts sell, and they also play to selling cars on dealership lots, even if the functional necessity is small or not necessary. Companies like Subaru typically aren’t tuning the car for minimum weight anyway... if they aren’t Lotus or other specifically focused manufacturers.
I had a 2005 Legacy GT with twin mufflers, albeit with one tip each, and it did sound mellower than a lot of other single-exhaust systems that were probably acoustically tuned to be loud.
Part of that is also resonator design, the previous owner of that Legacy had cut the resonator out, and put flow-master knock-off mufflers on the back of the stock Y-pipe... and it was atrocious, loud, and with an aggravating droning tone.
An 3” pipe expansion resonator, a 3”-2x2.25” aftermarket stainless Y-pipe, and 2 Magnaflow mufflers helped quite a bit... aside from the tech that assembled it, who welded the hangers not to the seams and end-caps of the muffler, where the joined metal is thick, but to the thinner stainless skin on the side of the muffler, and the hangers ripped the metal when it came apart. Sometimes jig-built, manufactured aftermarket systems are worth the money by being built right, apart from just the bare component cost.
boxrocket
> Grindintosecond
05/01/2015 at 19:10 | 0 |
I think Bill Cosby (never mind the accusations for now, he still has made great comedy), car guys have an instinctive need for piiiiiipes .
Aaaaand nibbles isn't letting me post images. Still and again.
Grindintosecond
> boxrocket
05/01/2015 at 21:44 | 1 |
Oh I love that album. Dad has a copy. It was great.
dsigned001 - O.R.C. hunter
> jvirgs drives a Subaru
05/01/2015 at 23:22 | 0 |
I really love that movie. My favorite Eastwood role so far.