Did My STI lose power?
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This is a discussion on Did My STI lose power? within the Comparison: WRX vs World forums, part of the Community - Meet other Enthusiasts category; Okay.. so I am not a street racer nor do I candone it. But I have a very good freind ...

  1. #1
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    Did My STI lose power?

    Okay.. so I am not a street racer nor do I candone it. But I have a very good freind with a E46 M3 and we play on some empty streches once in a while . When I had a Tbe and Ecutek 18 psi from a roll I would pull him 1-2 cars.. Now I have 308 whp Ontop of the Tbe and ecutek I have forged cp pistons and Vibrant headers ..anyways we did a few runs tonight and He pulled me on some???? and I pulled him from 2cnd to 3rd to 4th little by little BUT here is were I am confused as soon as I went into 5th ( not really on boost I guess) he would gain and pass me .. but from 60 4th gear I pull him about 1-2 cars..
    I feel like my car has to much lag I get full boost at 4100 rpm below that it's not that peppy..I am also running 20 psi now .
    His mods are a exhaust and alot of carbon fibre..

    Did I lose power can something be wrong with my car?
    I want to get it Dynod again to make sure..
    Oh and I am on snow tires not sure if that makes any diff.
    Thanks..
    Sorry I read this over what I wanted to say at the end was that if we line up from 60 mph -120 ish I pull him the 2 cars but from the lower gears 2-3-4 and going into 5th I lose my lead but start at theend of 5th to gain again..
    Last edited by zigger; 11-01-2005 at 08:51 PM.

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  3. #2
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    your motor might be knocking and the ecu is pulling timing.. your still hitting full boost if not more but because the timing is retarded your not seeing the full benifits of it, have it checked out before it becomes sumthing worse
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    U think?

    I'll see my tuner

  5. #4
    Registered User zapman's Avatar
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    you might have a boost leak.

    you retuned it after adding that stuff right?
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  6. #5
    Moderator YBNormal07's Avatar
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    Your headers might be at fault. If I remember correctly, headers on the STi drop the torque but raise and smooth out the HP band. Thus, less grunt in the lower gears, better topend in the higher gears. Just a thought.
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  7. #6
    Registered User 04wrx4keeps's Avatar
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    I would put another vote in for the headers being your problem. You may have gone up in peak HP but lost some usable horsepower in the lower RPM's. Especially if the headers are not heat coated, you get good spoolup from the stock manifold because it retains alot of heat and therefor exhaust pressure which spools the turbo up much quicker. If you're loosing too much heat through the headers you may make a higher peak number due to the increased flow at high RPM's, but lose spoolup and low-mid power because of the exhaust velocity loss in the lower RPM's, and possibly a change in the exhaust pulse pattern. This is why most tuners will recomend you dont mess with the headers until your running a much larger turbo than stock. I know this is true for the WRX and I'm guessing its probably not too much differnt for the STi. Stock manifolds on both cars flow well and arent really a restriction untill you're pushing much higher than stock numbers.

    When you get the car dyno'ed again, if you have dyno charts from before the headers compare the whole line, dont go off peak hp numbers. Bigger peak hp numbers are great, but if you make them at the expense of power elsewhere in the curve overall performance will suffer drastically. especially with rolling starts where you're not always in the sweetspot.
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  8. #7
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    problem solved

    for all of your replys. I took it to my tuner and we did a road test and loged some runs the problem was that my car was tuned in August really hot here and now in Canada it's really cold so my car was OVER BOOSTING that is why my car was falling back from 4th to 5th so he changed a little metal peice in the hose? I think he said its called a pill? anyways so ya that shaved off just under 1 lbs of boost and we loged some runs and I now get full boost at 3700 rpm.. much much better..
    now I'll run him again !!

  9. #8
    Registered User 04wrx4keeps's Avatar
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    Quote Originally Posted by zigger
    for all of your replys. I took it to my tuner and we did a road test and loged some runs the problem was that my car was tuned in August really hot here and now in Canada it's really cold so my car was OVER BOOSTING that is why my car was falling back from 4th to 5th so he changed a little metal peice in the hose? I think he said its called a pill? anyways so ya that shaved off just under 1 lbs of boost and we loged some runs and I now get full boost at 3700 rpm.. much much better..
    now I'll run him again !!
    good deal, glad to hear you got it straightened out
    Cobb Stage 2.5 VF-34 + uppipe
    Best ET so far - 13.1@103 with a 1.81 60'

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