Exhaust system for performance

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Exhaust system for performance

Postby Newbie GT » Wed Apr 17, 2013 3:37 pm

Hi guys would this setup be the best for a tuned get but keeping stock muffs

Xforce dump
3 inch centre high flow cat
3 inch y pipe ?? This is the part I'm confused about as lot of members seem to use stock
Thanks
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Re: Exhaust system for performance

Postby Kekotic » Wed Apr 17, 2013 3:38 pm

You cannot use the stock y-pipe because the centre pipe and y pipe are one piece. Changing the centre means changing the y pipe too.
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Re: Exhaust system for performance

Postby Newbie GT » Wed Apr 17, 2013 3:53 pm

chaotic2050 wrote:You cannot use the stock y-pipe because the centre pipe and y pipe are one piece. Changing the centre means changing the y pipe too.

Thanks Kiern

So would a 3inch system all the way including Y pipe be best for performance ?
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Re: Exhaust system for performance

Postby Kekotic » Wed Apr 17, 2013 4:01 pm

Newbie GT wrote:
chaotic2050 wrote:You cannot use the stock y-pipe because the centre pipe and y pipe are one piece. Changing the centre means changing the y pipe too.

Thanks Kiern

So would a 3inch system all the way including Y pipe be best for performance ?


3" all the way is probably overkill if you are using the stock mufflers. But if you plan to upgrade them in the future you could get 3".
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Re: Exhaust system for performance

Postby kiahatsiu » Wed Apr 17, 2013 5:24 pm

I would most certainly do 3" to your mufflers. Think of it as future proofing.
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Re: Exhaust system for performance

Postby DonGreen » Thu Apr 18, 2013 12:22 pm

Regarding stock mufflers, has there never been a replacement twin-outlet muffler made for a 3 inch system?

I would think that would be a preferred option of a lot of STI owners going to a 3" system.
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Re: Exhaust system for performance

Postby dr20t » Thu Apr 18, 2013 12:34 pm

Twin 3" y pipe is overkill

2.25 or 2.5" y pipes will suffice and are what most systems run

3" will give a heap of drone for not much performance unless you're going for 500kw
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Re: Exhaust system for performance

Postby Manaz » Thu Apr 18, 2013 12:54 pm

dr20t wrote:Twin 3" y pipe is overkill

2.25 or 2.5" y pipes will suffice and are what most systems run

3" will give a heap of drone for not much performance unless you're going for 500kw


For an NA engine, I'd say yes (particularly because for a given volume of gas, flow is actually faster through a narrower pipe, and you get better scavenging effects). For a turbo, where the last thing you want is backpressure and scavenging isn't really an issue (valve overlap, required for scavenging, can be your enemy with boost), I'd question this.

3" with appropriate mufflers (may need a centre resonator) shouldn't be too loud.
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Re: Exhaust system for performance

Postby dr20t » Thu Apr 18, 2013 3:05 pm

Sorry but you're wrong

Twin 3" pipes have a total surface area of 9.42 inches

Single 3" pipe has total surface area of 4.71 inches

Twin 2.5" pipes have total surface area of 7.84 inches

So therefore twin 2.5" pipes have greater cross sectional area than a single 3", by almost double. The limitation will still be at the entrance to the 2.5" y pipe which is 3"

Therefore you are NOT losing flow going from a singe 3" to twin 2.5

As an example, my car made 255kw atw with a 3" to twin 2" y pipes

I'm only now upgrading to twin 2.5" y pipes as I'm chasing alot more power

3" single systems to the rear muffler work on almost all 4 cylinder turbo cars up to 400kw so can't see a single 3" being a restriction

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Re: Exhaust system for performance

Postby Manaz » Thu Apr 18, 2013 7:52 pm

dr20t wrote:Sorry but you're wrong

Twin 3" pipes have a total surface area of 9.42 inches

Single 3" pipe has total surface area of 4.71 inches

Twin 2.5" pipes have total surface area of 7.84 inches

So therefore twin 2.5" pipes have greater cross sectional area than a single 3", by almost double. The limitation will still be at the entrance to the 2.5" y pipe which is 3"


Now that you're clear that you mean 2 x 2.25" or 2 x 2.5" vs single 3", I agree entirely.
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Re: Exhaust system for performance

Postby Newbie GT » Fri Apr 19, 2013 9:17 pm

So the Y pipe is the best investment am I understanding right ?

Basically 3 inch all the way ?
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Re: Exhaust system for performance

Postby Kekotic » Fri Apr 19, 2013 9:36 pm

re read the thread...
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Re: Exhaust system for performance

Postby Deep Heat » Fri Apr 19, 2013 9:58 pm

dr20t wrote:Sorry but you're wrong

Twin 3" pipes have a total surface area of 9.42 inches

Single 3" pipe has total surface area of 4.71 inches

Twin 2.5" pipes have total surface area of 7.84 inches

Mick


Umm Mick your numbers are wrong, you didn't square the radius.

Twin 3" = 14.14 inches squared

Single 3" = 7.07 inches squared

Twin 2.5" = 9.82 inches squared
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Re: Exhaust system for performance

Postby dr20t » Fri Apr 19, 2013 10:23 pm

Newbie GT wrote:So the Y pipe is the best investment am I understanding right ?

Basically 3 inch all the way ?


R u fkn serious? :?

No helping some people seriously...

Twinkle I calculated cross sectional area not surface sorry

But you get my point

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Re: Exhaust system for performance

Postby Boostaddict » Fri Apr 19, 2013 11:23 pm

Hahahaha

Love this thread.

Newbie ..... No idea.

Mick.... You come out with some awesome shit man!! Love it
Not a Subaru...... Something MUCH better

NOPE..... That's shit too. Bus anyone??
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