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Thread: 2"5' or 3" system turbo back

  
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    Iain M's Avatar
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    2"5' or 3" system turbo back

    Right bit confused really, read on here for big power you need 3" and spoke to blue flame and they say you need 3". But I phoned the place that does the exhaust systems next door to red dot and they say 2.5 is good for 400 and that I would loose lower end power. Don't know what to do know r who to beleive. What are you lot running.
    Also would I be able to get just backbox changed?
    Drives - 272Bhp Corsa Z20LET with 314ft-lb Torque

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    welsh-andy's Avatar
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    well i got 280bhp on a 2 1/4" thats was a red dot remap, and oggy explain my zorst bore was why couldnt go higher, so i fink 2 1/2" would be fine over 300bhp

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    f4af100uk's Avatar
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    Id say 2 1/2" is fine for upto around 330bhp. If you wanted more id get a 3" just to help take the heat away from the engine.

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    Vintorez's Avatar
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    taken from a part of text written by a turbo systems engineer who works for Garret

    As for 2.5" vs. 3.0", the "best" turboback exhaust depends on the amount of flow, or horsepower. At 250 hp, 2.5" is fine. Going to 3" at this power level won't get you much, if anything, other than a louder exhaust note. 300 hp and you're definitely suboptimal with 2.5". For 400-450 hp, even 3" is on the small side.”
    full page here!

    http://www.max-boost.co.uk/max-boost...st/exhaust.htm

    obviously its not exactly the be all and end all to the massive discussion, but its a good wedge. ive got a 3" and ultimatley aim for 400bhp.
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    Rainey88's Avatar
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    what width are the standard Z20let exhausts anyone know ?

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    2.25" bore

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    slim-shany's Avatar
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    i was running 292bhp on eds 3.5,and that was on a full 2.25 system with sports cat.(bar a 2.50 inch pre-cat)..since fitted full 3'' inch piper but not had it on regals rollers yet..do you think i will gain or lose bhp???

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    hott4u's Avatar
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    Cant beat the sound of a full 3" stainless !!

    Power wise 2.5 will be fine for anything around 300bhp and you wont lose any power with a 3"
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    robtoogood's Avatar
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    i would say gain a few bhp, less back pressure than the other zorst. You man lose a little torque though.
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    Iain M's Avatar
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    Thanks guys will stick with 2.5 then just gonna change the backbox and sort the exhaust blowing then.
    Drives - 272Bhp Corsa Z20LET with 314ft-lb Torque

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