Power Flow Exhausts

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andy & fonz
Joined: Tue 28 Jul, 2015 18:35
Posts: 52

  Z3 roadster 2.2i

Power Flow Exhausts

Post by andy & fonz » Wed 18 Jul, 2018 09:34

Hi
Thinking of going down the power flow exhaust road, you good folks that have had them fitted have you seen any improvement in power or mpg, asking because the fitter at mr tyre says unless I go silly on noise levels there will be little or no gain over the BMW set up, getting to old for boy racer noise levels.
Thanks for the feedback

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Gazza
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Joined: Tue 04 Oct, 2005 21:58
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  M roadster S54
Location: East London/Essex

Re: Power Flow Exhausts

Post by Gazza » Wed 18 Jul, 2018 19:39

I’ve not had Powerflow but did have Pro-Speed rear boxes.

I can’t say I noticed any difference in performance but easily noticed the drone at 30mph.
Gazza

"Understeer is when you hit the wall with the front of the car, oversteer is when you hit the wall with the rear of the car. Horsepower is how fast you hit the wall and torque is how far you take the wall with you"

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Southernboy
Joined: Thu 07 Oct, 2010 13:39
Posts: 6364

  Z3 roadster 3.0i
Location: Johannesburg

Re: Power Flow Exhausts

Post by Southernboy » Sun 22 Jul, 2018 06:46

On any modern car, it's the cat converters which create the greatest restriction to getting the exhaust gasses out. So, if you want to achieve a small power gain, you have to dump those. Whether your laws allow this or not will determine your decision. In any event, the gains aren't so significant that you would notice much. You will notice a fuel consumption improvement if you made a careful study of a before and after removal.
Oddly, it's the emissions controls on cars which have robbed much of the power, but at the expense of higher fuel consumption. If you really want improved performance, the only practical way is to replace piston rings, and do a head job - valves, valve seals etc.
The cylinder head is by far and away the most critical area of power since that's where the greatest pressures are created. Ant "leaks" past both intake and exhaust valves will result in poor combustion and loss of power. Piston rings are the only other component which relates to effective combustion / power, since they provide the "seal" on the actual strokes.
Doing the job isn't as difficult as it may seem at first and with a decent manual like a Bentleys, it can be comfortably achieved. The only obstacle is cost. In the process of doing a head job, there are a variety of tools required, and parts which need replacement whether you like or not. Obviously, time and space to carry out the task is a prerequisite too. However, once done, you will be grinning from ear to ear with the huge power gain. Your motor is essentially new again, with all the original horses hauling ass... :D
I have rebuilt a few BMW motors and have done them in the most economical way I could each time, and the results have been a success every time.
"Normal is overrated"
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Mike
Joined: Wed 14 Apr, 2004 11:53
Posts: 286

  Z3 roadster 2.8
Location: la Gacilly, France
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Re: Power Flow Exhausts

Post by Mike » Sat 11 Aug, 2018 10:14

Id powrlow exhaust for 12 years. very good but make sure you get the quietest available or you'll go mad wiith it

4wheels
Joined: Sat 24 Sep, 2016 20:42
Posts: 77

  Z3 roadster 3.0i

Re: Power Flow Exhausts

Post by 4wheels » Thu 16 Aug, 2018 22:11

has anyone replaced the cats with 300CEL cats or something? (more like racing cats)?

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