Some Subaru queries.

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Tornado

Tornado

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I've been wondering about a couple of things vaguely related to Subaru, and I was wondering whether anyone has the answers.
  1. In a normal 4 cylinder engine, I've read that dual exhaust carries no performance enhancement whatsoever because there is only 1 cylinder bank. However, in a boxer 4 cylinder, does dual exhaust carry similar benefits to, say, a V6? Furthermore, does an inline-6 also carry no benefits to a dual exhaust system?
  2. What does the bar on the back of Subaru Outbacks do? Does Subaru legally condone skitching? Or do they think their buyerset is legally retarded so they cannot open the rear hatch?
 
Toronado
I've been wondering about a couple of things vaguely related to Subaru, and I was wondering whether anyone has the answers.
  1. In a normal 4 cylinder engine, I've read that dual exhaust carries no performance enhancement whatsoever because there is only 1 cylinder bank. However, in a boxer 4 cylinder, does dual exhaust carry similar benefits to, say, a V6? Furthermore, does an inline-6 also carry no benefits to a dual exhaust system?
  2. What does the bar on the back of Subaru Outbacks do? Does Subaru legally condone skitching? Or do they think their buyerset is legally retarded so they cannot open the rear hatch?
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exhaust always depends on the size and flow of the exhaust, versus the size and flow of the engine. A 500hp I-4 could gain some power with dual exhaust, but on a 200hp car, it might actually cause a power drop.

What is skitching? Why would you even wonder if they think their buyerset can't open the hatch?
 
Like the one on this Scooby:
6618493479.240220064.IM1.05.240x180_A.240x180.jpg
 
Toronado
In a normal 4 cylinder engine, I've read that dual exhaust carries no performance enhancement whatsoever because there is only 1 cylinder bank. However, in a boxer 4 cylinder, does dual exhaust carry similar benefits to, say, a V6? Furthermore, does an inline-6 also carry no benefits to a dual exhaust system?
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You would think that you could just as easily route two cylinders to one side and two to the other in an inline engine. I don't see why you would run two exhausts off a low power engine though. I'm sure power plays a role in that too.

I don't think it's just a Subaru situation either. Our V70 XC has a bumper designed for two exhaust outlets yet one of the outlets has a cap on on the bumper yet a muffler (and I presume more piping) which I would guess is blocked off. Maybe they run two outlets on non-inline engines.

What does the bar on the back of Subaru Outbacks do? Does Subaru legally condone skitching? Or do they think their buyerset is legally retarded so they cannot open the rear hatch?
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I don't recall ever seeing one with such a bar on it.
 
Ya I have never seen that bar either, maybe it's a dealer accessory or something.
 
Really? I'd put money on Outbacks (in particular) and Foresters being more common with the bar than without around here. I just assumed that it was part of a trim package or something. That does explain why they are so hard to find pictures of on the internet, though.
 
Philly
Our V70 XC has a bumper designed for two exhaust outlets yet one of the outlets has a cap on on the bumper yet a muffler (and I presume more piping) which I would guess is blocked off. Maybe they run two outlets on non-inline engines.
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I believe the muffler that doesn't have an exhaust tip, has piping that goes over to the second muffler that does have the tip...course I'm not 100% sure on that.
 
Toronado
Really? I'd put money on Outbacks (in particular) and Foresters being more common with the bar than without around here. I just assumed that it was part of a trim package or something. That does explain why they are so hard to find pictures of on the internet, though.
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there isn't one on my fiancee's grandfathers 98 sub forester s.
But since the hatch doesn't "fly" open, and must be pulled upward, I'd guess it's a handle for lifting the door:scared:

He got his in Oct.
Now, this month, first, the driver's side balljoint snapped, left us stranded, then, just fri. night I put a new clutch slave cylinder, that got bad enough I had to drive home without using the clutch, once shutting the car off just to get into first gear at a stop sign(crosswalk lifeguard).

The CV joint connecting to right-side passenger wheel has been clacking more and more for a month, so we must replace that half-shaft.

And sat night, (the night after i put the slave sylinder in) something in the wheel(ish) are is screaming, it sounds like an icepick on glass when the wheel rotates, whether, forward, backward, in gear, out, & on the brakes, as well as off. Oh, and turning any direction too.

I don't know how much he paid the shop to fix the balljoint, but I know the slave cylinder cam to $54.54 and a wheel bearing is $40.

And the check engine lights been on for months.
 
Twin exhausts are unnecessary on most cars with displacements of less than say 5 liters. Arbitrary number I just picked out.

But until about ten years ago, even the M5 had a single exhaust. The whole dual exhaust thing is like the bigger rims thing; supposed to impart performance, but really only adds weight.

Exhausts are tricky because few people know how to make them yield more power. You have to size them just right, start with the right size collector/ headers, increasing the size gradually as you go back. Just two or three steps. You also have to keep the heat in it, optimise the flow of the exhaust, size the collectors length so that the pulses scavenge the adjacent cylinders etc etc etc. Just putting two big pipes and Flowmasters does nothing for power. Just sound.

I believe that grab bar thing is so people can open the hatch with gloves or mittens on.
 
neanderthal
Twin exhausts are unnecessary on most cars with displacements of less than say 5 liters. Arbitrary number I just picked out.

But until about ten years ago, even the M5 had a single exhaust.
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So the 360/F430's etc have them just for looks?

Speaking of BMW's, yes the E34 M5's had single exhausts, but my old mans E38's have both had twin exhausts ('94/'95, 3 litre and 4 litre V8's). Pretty sure the E39 M5's have twin exhausts anyways, and they were what, a litre short of your 5 litre guesstimate?
I also think the reason E34 M5's had the single exhaust would have more to do with the i6 engine than any performance/weight ratios.

Personally, and basing this on nothing scientific in any way, most 'V' or boxer engines would be better off with twins, without having the gases from each bank impede each other, and theoretically the piping would be shorter as well...
 
Having a twin exhaust increases exhaust volume. A car with more power is pumping out more exhaust gases, meaning a twin exhaust will keep up a healthy rate of flow. Nearly all factory spec twin exhausts are restricted as hell, because if you have too much of an exhaust volume, the pressure doesn't keep up (in lower powered vehicles) meaning the exhaust isn't coming out at the rate it should and therefore the power drop. That's the way I see it, and so in short, yes, twin exhausts from the factory are functional, but in most cars are really just there for looks because of the way they are designed.
 
slidesquad#1
So the 360/F430's etc have them just for looks?
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my money says they dont actually increase performance as per what i wrote. so yes, i believe they are just for looks. on extremely high performance cars perhaps not, but i stand by what i said.

lets put this in perspective; how many race cars have you seen with dual exhausts?

and like i said, the number was an arbitrary number.
 
neanderthal
lets put this in perspective; how many race cars have you seen with dual exhausts?
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Not 2 pipes, but 6 :eek:
toddkellybahrain07side1zu6.jpg


Look, dual exhaust will offer a power increase, but only if you have enough power to back up the flow.
 
Aren't those like turbines though?...I'm sure they would only need one exhaust so that doesn't really count.
 
buickgnx88
Aren't those like turbines though?...I'm sure they would only need one exhaust so that doesn't really count.
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When you get that big of an engine, couple it on a tractor, add a typical redneck driver, and that's what you get.

Shoulda got a John Deere
John%20Deere%20720%20Pulling%201.JPG
 
so lots of race cars have dual exhausts. now, how many of those have displacements of less than 5 liters.

and power wise, how do they compare with a standard subaru?
 
As I said earlier, the production model vehicles will have a very restricted system, so restricted it would have no difference in exhaust volume to a single exhaust.

Also, I believe DTM and JGTC cars will have dual or more exhausts and I think they're all under 5.0L displacement.👍
 
Most Racers have Duals because of the sheer amount of airflow going through the engine. Every Formula 1 car (now that there's no turbos) has two exhaust pipes. The engines are...what, now, 2.8L?

On that point, I don't think I've seen many hi-po VW motors with dual exhaust, most just a single...really loud...muffler. Even Porsches have an interconnected muffler system.
 

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