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Old 04-28-2013, 01:19 AM   #1
DKdekes
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Default single exit exhaust inquiry

I got the invidia n1, which is a single exit exhaust, and was looking under the car the other day and realized that there is a gigantic cavity from the absence of the muffler of the stock exhaust (hatchback). This looks like it would have an effect on the car in some way. So has anyone noticed any problems (eg gas mileage, handling problems arising from turbulent air) from this cavity?
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Old 04-28-2013, 01:41 AM   #2
garzdos
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OMGHi2U

Never thought about this but makes sense there might be some consequence to this change...interested in hearing what others have to say...
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Old 04-28-2013, 02:42 AM   #3
Thunderpaw
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A strong wind would affect your mpg more
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Old 04-28-2013, 08:22 AM   #4
Navendra94
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...........Are you one of those guys who think a fart would make a car "unstable"?

FWIW, it's an exhaust... get it wind tunnel tested of you're worried. -_-
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Old 04-28-2013, 09:29 AM   #5
garzdos
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In a way it is comparing apples to oranges, but I know from personal experience that when I had a pick up truck there was a noticable difference when it came to strong winds or increased speeds if the back of the truck was empty or not and if the tail gate was up or down. I mention this because, while smaller on the bottom of theSubie, both are a "pocket" of empty space and I can see how aerodynamics might change (however slight or minimal this might be).
I don't have the answer but it just seems the OP's question/concern is not unreasonable.
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Old 04-28-2013, 10:58 AM   #6
S1CkWrx
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who cares just drive the car
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Old 04-28-2013, 11:17 AM   #7
some dude
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No, I think you should care and not drive the car.
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Old 04-28-2013, 11:55 AM   #8
Napalm3nema
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I think you'd have to take pictures of the bottom to judge? I can't picture the cavity. If it is a smooth entrance and exit to the pocket no worries. If it bleeds off to hit the inside of the bumper it could cause you to lose some mpg's. <shrug>

Need more information to judge I guess.
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Old 04-28-2013, 01:13 PM   #9
borderguy
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This is ****ing retarded.
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Old 04-28-2013, 01:25 PM   #10
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Empty cavities tend to have similar properties to ones that are filled. similar to a pickup truck with the bed closed, a vortex forms and creates a cusion othat new air flows smoothly over. Same thing happens in a liquid. You needn't worry.
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Old 04-28-2013, 07:56 PM   #11
urabuster
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Look up why a golf ball is dimpled.
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Old 04-28-2013, 08:12 PM   #12
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OP, are you driving the car in a race track?
Doing a top speed run at Bonneville??
Over active imagination?

Seriously, you're over thinking things. It's a Subaru, not a Ferrari.
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Old 04-28-2013, 08:59 PM   #13
Knale
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Unless you are tracking this car, I would be more concerned with the aesthetic's of that big gapping hole that was left behind. I wonder if there are any aftermarket remedies for this
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Old 04-28-2013, 09:33 PM   #14
MorganJ
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I bet it would start to affect the car in speeds above 150mph
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Old 04-28-2013, 09:33 PM   #15
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I like tacos.
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Old 04-28-2013, 10:17 PM   #16
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Quote:
Originally Posted by Screaming_Emu View Post
I like tacos.
Have you tried the cool ranch one yet?
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Old 04-29-2013, 01:25 AM   #17
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Yes, it will certainly have an effect and small aerodynamic changes can have huge effects on stability even at speeds as low as 70-80mph.

I can tell a massive difference in the handling at highway speeds when I remove the undertray for example.

It would be pretty simple to solve your problem by building a makeshift diffuser out of ABS or another material.
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Old 04-29-2013, 09:34 AM   #18
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Quote:
Originally Posted by lwszabo View Post

Have you tried the cool ranch one yet?
Nacho cheese is still better
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Old 04-29-2013, 11:11 AM   #19
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Quote:
Originally Posted by 08wrbrex View Post

Nacho cheese is still better
No way cool ranch ftw.
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Old 04-29-2013, 02:49 PM   #20
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Most likely a recirculation region will form in that pocket. There should be minimal effect. Worst case scenario is that it causes the flow to separate increasing drag. The whole golf ball dimple thing is a little different. The dimples trip the boundary layer to go turbulent which will stay attached longer.
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Old 04-29-2013, 11:08 PM   #21
DKdekes
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sorry about not watching the thread. il take some pictures tomorow to show you. And for those who are being stupid and/or saying if i dont track my car it doesnt matter, the reason they make the shape it is is to keep it as aerodynamic as possible, (with the exception of tmic on our cars i guess). il also post a few drawings right now possibly to diagram the situation a bit. Those of you talking about a turbulent air cushion have me listening
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Old 04-29-2013, 11:30 PM   #22
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Old 04-30-2013, 10:03 AM   #23
borderguy
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Happy Taco Tuesday everyone!
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Old 04-30-2013, 10:25 AM   #24
blehhh
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I saw a silver STI hatch with flaps and a flat-black N1 on NASIOC a while back and it looked wicked. So nice. I decided to stay with my stock exhaust for volume reasons, but if I were to go with a CBE, I'd have no reservations about dropping the quadtip for a flat-black N1.
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Old 04-30-2013, 10:53 AM   #25
greenplates
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Weight differences will not be noticeable
Horsepower gains will not be noticeable
Sound may be different
Appearance will be different


Which allows greater flow of exhaust? A more direct path to exit OR a multi routed exit?

[open headers ftw]
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