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Thread: will i loose power if i use a straight through pipe

  
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    will i loose power if i use a straight through pipe

    just had a powerflow custom exhaust fitted.. just want to know if im going to loose fuel eco and power by not aving the center section box. replaced it all with stainless steel 2" bore pipe... wasnt bothered about the noise i just wanted a stainless steel system that wud possibly help with power but also be future proof but maintain fuel eco..

    iv ran a search but didnt find the answer i was lookin for exactly..

    cheers in advanced..

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    Quote Originally Posted by craig20102010 View Post
    just had a powerflow custom exhaust fitted.. just want to know if im going to loose fuel eco and power by not aving the center section box. replaced it all with stainless steel 2" bore pipe... wasnt bothered about the noise i just wanted a stainless steel system that wud possibly help with power but also be future proof but maintain fuel eco..

    iv ran a search but didnt find the answer i was lookin for exactly..

    cheers in advanced..
    You'll gain power,but loose a bit of Eco m8 .
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    You'll gain power, the OEM centre box (and backbox) is very restrictive!

    As for economy, I'm darned if I can see any difference after 9 months of driving on my full catback system, and I do serious mileage!

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    ive not noticed any difference in fuel economy on mine always a good thing!

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    I can say the same about my system aswell

    Got a stainless centre section and backbox and noticed sod all difference in using more fuel
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    Can't see how you could lose fuel economy by making the exhaust less restrictive?

    Should be good for power and economy/but as power gains'll be less at low revs (where most driving is) economy won't be changed by much (if noticeably at all).

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    Quote Originally Posted by mania View Post
    Can't see how you could lose fuel economy by making the exhaust less restrictive?

    Should be good for power and economy/but as power gains'll be less at low revs (where most driving is) economy won't be changed by much (if noticeably at all).
    so ur saying the power gain will only be noticable in the higher rev range (above 3k)..

    wont it make a difference in Eco if you loose back pressure? which you would from putting a full system on with a larger diameter pipe... mines only increased to 2" though..

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    Quote Originally Posted by craig20102010 View Post
    so ur saying the power gain will only be noticable in the higher rev range (above 3k)..

    wont it make a difference in Eco if you loose back pressure? which you would from putting a full system on with a larger diameter pipe... mines only increased to 2" though..
    I wouldn't worry about it. I've done a little reading since my last post = sounds like backpressure is always undesirable (it's in the name - how can making the exhaust harder to push out of the car be good for fuel economy?), but the stock cams can be designed to take it in to account (if so, your fuel economy might get slightly worse). Had the car been tuned from factory though with the new exhaust, fuel economy would be better then with the stock one in all situations. I really wouldn't worry about it though - whether it's too noisy is more likely to be an issue.

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    Back pressure...

    What you alter on a less restrictive exhaust is the gas speed as it exits the exhaust. What you'll probably find is a little less torque lower down - because the exhaust gas exit speed is lower at lower speeds now because the restrictions were what kept it high.

    Top end you should gain because the exhaust gas can now move out of the exhaust quicker (more air going out of the exhaust at higher engine rpm's)...

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    Quote Originally Posted by nry View Post
    Back pressure...

    What you alter on a less restrictive exhaust is the gas speed as it exits the exhaust. What you'll probably find is a little less torque lower down - because the exhaust gas exit speed is lower at lower speeds now because the restrictions were what kept it high.

    Top end you should gain because the exhaust gas can now move out of the exhaust quicker (more air going out of the exhaust at higher engine rpm's)...
    decent well thanks for clearin that up...

    think i might get a stainless steel center section fitted since its loud around 2k - 2.5k so 50mph in 5th is a bugger.. every other speed if just sittin at a constant speed is quiet dont ave to turn the Cd player up to compensate...

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