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Thread: Exhaust mods and Powerband.

  1. #1
    Join Date
    Jul 2006
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    Exhaust mods and Powerband.

    Will the following exhaust mods increase an otherwise stock '93 sc's powerband, or simply make more power within its existing powerband?

    -ported 94 exhaust manifolds
    -2.5" downtubes with high flow cats
    -2.5" dual in 3" out resonator
    -3" pipe from resonator back to two 2.5" pipes and two dynomax super turbo mufflers

    What kind of power gains can I reasonably expect with these mods? The bends will be made with a compression bender.

    Thanks.
    Ted

  2. #2
    Join Date
    Mar 2006
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    411
    I did very similar exhaust mods and dropped about 2-3 lbs of boost but it breathed bettr up top and reved a littlequicker.
    I then put on a magneson sport withGTP rotors ported plenum 75mm tb 85mmMAF IC fan CIA intake Much better. it pegs the boost gauge at 4800rpm.
    You won't feel the real potential of the exhaust mod till you up the boost my car sounds very good underboost lots of intake whine and a low rumble.

  3. #3
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    Exhaust Mods

    Thanks for the reply. Are you still running the stock cam? Do you have an auto or a 5 speed? What gears are you running out back?

    Thanks,
    Ted


    Quote Originally Posted by 442guy View Post
    I did very similar exhaust mods and dropped about 2-3 lbs of boost but it breathed bettr up top and reved a littlequicker.
    I then put on a magneson sport withGTP rotors ported plenum 75mm tb 85mmMAF IC fan CIA intake Much better. it pegs the boost gauge at 4800rpm.
    You won't feel the real potential of the exhaust mod till you up the boost my car sounds very good underboost lots of intake whine and a low rumble.

  4. #4
    Join Date
    Mar 2006
    Posts
    411
    5 speed. stock gears for now 273 cant decide between 355 or 308.
    I did the exhaust first and noticed some bottom end tourque went away,but it felt stronger above 3500rpm. It all improved with the Sport blower plenum and intake mods. stock cam for now

  5. #5
    Join Date
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    NJ
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    I've got a '93 5 speed with a 3.73 posi pumpkin, so I doubt I'll notice the loss of low end torque with the new exhaust. What intake mods did you make?

    I'm thinking of complimenting all of this with a larger TB and MAF. I'd also like to upgrade to the '94/'95 Blower, plenum, and injectors. Its pretty much a DD that I do a lot of city driving with.

    Ted


    Quote Originally Posted by 442guy View Post
    5 speed. stock gears for now 273 cant decide between 355 or 308.
    I did the exhaust first and noticed some bottom end tourque went away,but it felt stronger above 3500rpm. It all improved with the Sport blower plenum and intake mods. stock cam for now

  6. #6
    Join Date
    Mar 2006
    Posts
    411
    PP 75 mm TB, 80 mm MAF Chromed 3 inch CIA, IC Fan, EEC re-learn very strong if I dip in on the gas too early my 255's go up in smoke!! Stock injectors for now will upgrade befor it gets hot again now I have nice cool weather and it flys!!! Yesterday I'm hitting 15PSI at 4300rpm

  7. #7
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    Nov 2004
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    Brantford, ON
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    and don't forget a tune after you change the injectors etc....... an EEC relearn will do didly squat for you after that type of mod.

  8. #8
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    Mar 2006
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    411
    yeah the plan is for Fuel pump,injectors ,gears and tune .

  9. #9
    fturner,

    When you say, "don't forget a tune after you change the injectors," what specifically are you suggesting be done?

    I am not new to cars -- many years spent wrenching -- just new to the SC-centric way of thinking.

    Second, what does one do to accomplish an EEC relearn?

    Thanks,

    Cammer

  10. #10
    Join Date
    Nov 2004
    Location
    Brantford, ON
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    5,383
    The computer in the car is set up for a stock configuration so its expecting a certain amount of air coming in at a certain throttle position and then it decides how much fuel to dish out. Think of it tuning the carb by adjusting the jets like the good ole days, only now we need to tell a little black box to do that adjusting for us.

    Now if you don't tell that computer that you just went bigger on the fuel injectors etc, you could end up running really rich to be dangerous to the health of your motor. Now if you don't go crazy on many other mods, you could get away with possibly using a C&L MAF with a sample tube fitted for the injectors you put in.... sure it works but you start porting everything, changing to a different cam and your back to square 1.

    Thats when you make arrangements with someone like XR7Dave, get some dyno time, buy a chip off him and he'll "tune" the computer for you for your mods.

    As for an EEC relearn, normally you pull the battery cable off for about 15 minutes, and that will wipe out the "adaptive" learning the computer has in memory. The adaptive learning is very limited and does not have a big enough scope to adapt to changes in fuel injector size etc.
    Last edited by fturner; 10-30-2006 at 09:17 AM.

  11. #11
    Thanks for the response, fturner -- you explained it perfectly.

    I was wondering just how far the factory computer could adjust as mods were made -- you answered the question, partly.

    Is there ever a time when, due to the significance/extent of the mods, that the factory computer can no longer be used, and a third-party, fully capable/adjustable computer must be installed?

    What company(s) makes a third-party computer for the SC?

    Cammer

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