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Old 03-30-2004, 04:58 PM   #1
scoobydrew06
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Default Ideal size exhaust tubing for 1.8?

anyone know this? I remember reading a thread a while ago about this but I could not find it.

It's 2.xx?
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Old 03-30-2004, 04:59 PM   #2
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and does anyone know the stock size?
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Old 03-30-2004, 05:36 PM   #3
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just slightly less than 2" IIRC
(had one for a while)

i wouldnt go over 2"
no point as there is no power...

Jamie - www.subiegal.com -
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Old 03-30-2004, 08:11 PM   #4
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1.75" is stock on a 2.2L and I think it shares the same exhaust ID with a 1.8L.

I went 2.25" on 2.2 liter and noticed a substantial loss in low end torque. It was enough to feel it on the butt dyno so I'm guessing a 5+ HP loss below 4000 rpms. Above 4000 rpms I probably gained 3-5 HP, but my driving consists in the lower rpms. This is my speculation, nothing proven on a dyno so don't take this information as a given.

I'd say the stock 1.75" is optimal for a stock 1.8L, and like Subie Gal said, I wouldn't go above 2.00" ID piping.

-Charles-
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Old 03-30-2004, 09:54 PM   #5
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hmmm...because i was just going to swap in a stock wrx catback.

should i just do some kind of axle back upgrade?
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Old 03-30-2004, 09:56 PM   #6
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or keep it bone stock...i just hate the puny lil tip coming out of my exhaust
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Old 03-30-2004, 10:02 PM   #7
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okay one more thing. Will the stock muffler section of a wrx bolt up to my stock midpipe?
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Old 03-30-2004, 10:21 PM   #8
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nope, not without a flange rotation and a hanger mod
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Old 03-30-2004, 10:31 PM   #9
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what is this so called flange rotation that you speak of. teach me your ways of fitment.

(i have access to a shop with a welder)
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Old 03-30-2004, 11:36 PM   #10
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2" is good (its what im using)
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Old 03-30-2004, 11:59 PM   #11
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the end of each pipe has a flange with two holes on it for the bolts to go through. when mating a wrx axle back up to a stock midpipe the holes don't line up for the bolts, so the flange has to be rotated so the holes line up. basically the old flange gets cut off and the flange gets welded back on in the right spot.
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Old 03-31-2004, 10:23 AM   #12
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Quote:
Originally posted by Subie Gal
just slightly less than 2" IIRC
(had one for a while)

i wouldnt go over 2"
no point as there is no power...

Really?? I read somewhere that 2.25" is the biggest u wanna go for the 1.8L. I doubt it'll make any difference though because the EJ18 has like no power to begin with.
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Old 03-31-2004, 12:25 PM   #13
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My rally/race car had a 2"... and did as well as he could do.

I wouldnt make it any larger than that, or you'd begin to risk power LOSS as the air just flows through the car aimlessly... you want and need a little bit o backpressure here n there...

few pix






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Old 03-31-2004, 12:42 PM   #14
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so subiegal...what would you suggest to do for an axleback?
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Old 03-31-2004, 01:01 PM   #15
Subie Gal
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Quote:
Originally posted by scoobydrew06
so subiegal...what would you suggest to do for an axleback?
depends on what you want.
stainless steel or?

very likely you'll have to have something custom made.
we just cut off the muffler and did a straight 2" pipe out the back

but any exhaust tuner could make up a nice 2" cat back for you...


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Old 03-31-2004, 01:21 PM   #16
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i'll prolly just order some 2" piping from jc whitney and rig one up myself.

thanks for the info.
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Old 03-31-2004, 05:08 PM   #17
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Why not go to your local muffler shop and get them to replace the piping from the last catalytic converter back with 2.00?" I think you'll need 7 feet of 2.00" at $3 - $5 per foot. Of course, this is the price for 2.00" aluminized piping which typically will last 7+ years. I wouldn't dare let any muffler shop crush bend stainless steel piping because its way to expensive and muffler men/women aren't exactly perfect and do not typically carry stainless tubing.

Preferrably have the pipe bent with a mandrel bending machine because it keeps the internal diameter of the piping close to 2.00." However, around my parts (central VA) these are rare, if not extinct. Good luck with whatever route you choose.

-Charles-
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Old 04-01-2004, 01:00 PM   #18
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Quote:
Originally posted by Subie Gal
My rally/race car had a 2"... and did as well as he could do.

I wouldnt make it any larger than that, or you'd begin to risk power LOSS as the air just flows through the car aimlessly... you want and need a little bit o backpressure here n there...

Hhmm... I learn something new everytime I come on here! So how much of a difference does it make going from 1.75" to 2"? Anything noticeable? Do u have a axleback or a catback or what?
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Old 04-01-2004, 05:40 PM   #19
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I have a custom 2.25" catback on my L. With the intake and exhaust midrange from 3000-4000 rpms was improved considerably. It pulls hard between 3 and 4000.
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Old 04-01-2004, 09:22 PM   #20
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Quote:
how much of a difference does it make going from 1.75" to 2"?
You probably won't feel a difference, unless you mentally want to feel the difference. I'd guess, 2-4 HP, maybe a little better gas mileage. Just a guess though.

-Charles-
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Old 04-02-2004, 10:52 AM   #21
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i guess i'm just going to put on a oem wrx muffler section then. Just to give it a lil bling
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Old 04-02-2004, 12:00 PM   #22
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Jamie, is that you in the background with the Yellow and white jumpsuit?
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