Interesting manometer findings (for those interested)
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  1. #1
    Fellow Frogger!
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    Interesting manometer findings (for those interested)

    Fitted the DIY manometer today, and was repeatedly able to record just under 14" of water (peak) at WOT in 2nd gear.

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    With a manometer, 1psi works out to be 27.68 inches of water. I've pretty well worked out that the GTi6's intake system has, at its highest demands, a 0.5 psi restriction.

    I'd say all of that restriction lies in between the intake pickup point (in front of the radiator) and the entry to the filter, as the path from the throttle body to the filter is very smooth.

    I'll plumb in the manometer in front of the filter next weekend to see if this is true.

    But basically, there's nothing wrong with this intake system. By eliminating all restrictions and having a noisier intake, I'd benefit at best 3 hp at the wheels.

    Given that 0.5 psi will only work out to be 5 or 6hp at the flywheel on a 2L motor (ora 2% difference in the GTi6 motor) I find it very amusing all of the claims that airfilter manufacturers make...(5-10% more power etc etc).

    One place has a kit that promises 3Kw at the wheels by removing the standard airfilter/intake assembly and whacking on a shiny pipe with pod filter (breathing air virtually right behind the radiator).

    Considering a kit like that is breathing air that's much, much hotter than what the factory setup would allow, the power claims these people make suggests an ENORMOUS restriction lies in the factory intake, which I have just proven is not true.

    Please tell me when I'm being boring, I'm just trying to help people make REAL modifications to their cars, and save some money on the dud ones.

    Cheers,
    Adrian

  2. #2
    COL
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    Good on you Adrian. It does make you wonder where manufacturers do get their figures from, maybe they are worse cases and expect us to believe its true right across the board.

    Regards Col
    Regards Col

    1973 Renault R12 Station Wagon
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  3. #3
    Fellow Frogger!
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    Adrian,

    Mate when a engine like the gti6 can put out 167 or so hp without variable cam timing there usually aint much you can do to the motor without killing emmitions & economy.
    Peugeot created a nice Motor car and i could of told u without the meter that there is hardly any restriction if there were it aint going to be putting out those magic numbers.

    Murat

  4. #4
    Fellow Frogger!
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    I was aware of that dude, it was an interesting experiment however... and my ultimate goal was to "share the knowledge!"

    It's a sweet motor, just look at the torque curve...pretty well flat from 2500rpm to 6500rpm - you'd be nuts to play with the cams unless it was a race car.

    My next experiment will be to test with my temperature probe the inlet air temp. I think my findings will be positive (as it's in a high pressure area in front of the radiator).

    I find it interesting, however my neighbours thing I'm a weirdo! I probably am

  5. #5
    Fellow Frogger!
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    Also Murat - I'm aware you probably could have told me, however when you're on the net, who do you believe?

    I decided to do a scientific test to prove it for myself.

    Half the people who offer glowing reports about the performance of their pod filters either have no direct comparison with the standard setup, or have interests in selling their filter products, or are in bed with K&N, Unifilter etc etc.

  6. #6
    Fellow Frogger! DTwo's Avatar
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    Default

    Most of those reviews are from people who have been sucked in (pardon the pun)

    Induction roar seems to have some sort of placebo effect when it comes to percieved performance, the louder the faster.......

    Similar story with the exhausts on some cars.......
    ________
    Marijuana Gifts
    Last edited by DTwo; 22nd August 2011 at 05:44 AM.

  7. #7
    Fellow Frogger!
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    Yep, mine pulls just as hard with the 2" flanged pipe welded in the 2.5" muffler outlet and it's reduced all of the boom in the cabin.

  8. #8
    Fellow Frogger!
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    Adrian,

    Yeah it is nice to have a fiddle around mate
    It never hurts to find out for sure
    And yes after a while when u have worked on cars long enough it is hard to beleive all the crap the companys spin.

    Murat

  9. #9
    Guru davemcbean's Avatar
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    ntrx:
    Yep, mine pulls just as hard with the 2" flanged pipe welded in the 2.5" muffler outlet and it's reduced all of the boom in the cabin.
    Yeah, I think this is the way to go with exhausts. My 2.25" system was too boomy until I shoved a small length of 1.25" up the tail. The performance drop is somewhere between miniscule and zero and it's alot more pleasant to drive. Basically, a very short piece of smaller diameter pipe causes very little restriction when compared to a whole exhaust system made of small diameter pipe. Obviously, though, if you make the end tip too small, things will bank up at high revs.

    On my 404, I had a 2" system, which was too noisy until I had a 1.75" tip fitted. Then it was just sweet.

    Big tips are just too boomy.

    Dave
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  10. #10
    Fellow Frogger!
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    Exactly Dave - I really wonder how some people can deal with it! My whole interior resonated at highway speeds, then it damn near vibrated on deceleration... eek!

    I was surprised as it was simply a muffler change... the original one must have been substantially baffled.

    Initially I was a little dismissive when the exhaust guy started fitting a little pipe in the exhaust, as I thought it looked a cheap and nasty fix.

    But the results speak for themselves, and the extra surge I experienced is still there.

  11. #11
    Guru davemcbean's Avatar
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    I think the secret to the small tip is that it interferes with the large bore exhausts' resonant frequency and thus stops the booming. It's a bit like sticking a small tip on an organ pipe.

    The air flow is hardly changed at all, since it's only a momentary constriction. Compared to a hot dog muffler with punched in louvres, the small straight pipe is very free flowing.

    Dave
    NZ Fleet
    1976 504 Ti
    1984 205 GT twin carb
    1991 205 SI 1.6GTI motor
    1994 106 Xsi
    1996 Mondeo V6
    Aus Fleet
    1955 203C
    1997 Civic Cxi (great allrounder- revy, flexible, nimble, comfortable , economical, simple and durable )

  12. #12
    1000+ Posts The Gonz's Avatar
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    Icon10 Fuego Exhaust Option?

    I like where this is going. What do you suggest I fit to replace the blown out muffler on my Fuego? (No bad language or anatomical references, please)

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