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  1. #1

    Default My 4.8 needs more power. Help Me

    what are some ways I get more horsepower out of my 07 silverado 4.8?
    I have a 05 silverado 5.3 and it runs like a race truck. the only thing I done to the 05 is add dual exhaust.

    please help

  2. #2


    Dozens of things can be done, more air in, more air out. Duals, tune, etc. Want to spend a lot of money, add a supercharger, or a turbo.

    For the money, I think a retuned PCM is the best way to go.

    '09 Avalanche LTZ - Black
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  3. #3


    I kind of new to the truck thing. I know PCM is powertrain control module. But is that like a Bully Dog or something. Dont laught at

  4. #4
    Jr. Apprentice
    Join Date
    Dec 2011
    20 mile north of Pittsburgh


    hi just thought i would chine in i have had three 4.8's 2 where 1999s and my current is a new body 07 as power goes both 99s would eat my 07 for lunch power and milage both suck 14.5 highway old 99 i bought new would get 18+ highway . if you find an answer to this problem let me know love the truck for ride and handling also load capacity best hualing 1/2 ton i ever had but slugish on power

  5. #5


    if I ever buy a new truck I am just going to get one with the biggest engine they got! However, the custom tune, and 4.10 gears made a world of difference for my 4.8.

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  6. #6


    Cold air intake, open up the exhaust, and hop up the ECM, and you'll get better power. I'm not even sure you are talking about a V8 or not. But the same principals apply to any motor, I just don't know what's all out there for the 4.8.
    Brian L.

    Brian Larson CST. KC9DAK.
    Janesville WI.
    87 GMC G20 6.2 diesel.

  7. #7
    Sr. Mechanic larryleeUSN's Avatar
    Join Date
    Jun 2009
    Now stationed in Mayport,Florida


    just to add to the other advice. i had a 4.8 in my 06 and i did exhaust, diablo predator programmer, cold air intake and a throttle body spacer. and after i lifted it 11 inches i ran 4:56 gears in it and it had plenty of power with 35's. i constantly pulled a 18ft car trailer with various cars and mud trucks and it was all the power i needed. you are probably running 3:42 gears so id recommend changing the gears out to a good set. and think about future plans so you wont ever have to worry about gears again.
    Lawrence Lee,United States Navy, Engineering.
    2008 Silverado CC. Z71 4x4. leveling kit on with exhaust hopefully putting on soon

  8. #8


    Quote Originally Posted by whoisMDU View Post
    I kind of new to the truck thing. I know PCM is powertrain control module. But is that like a Bully Dog or something. Dont laught at
    Yeah, the Bully Dog does the same kind of thing. A custom tune is a new program loaded into the factory PCM to replace the GM program.

    From the factory, the PCM is programmed to provide good MPG and to protect (read reduce GM's warranty costs) the transmission and drive-line.

    A custom tune will remove some of the power retarding in the stock PCM, letting more power get to the wheels when the driver wants it (from a stop, or passing). Some have even insisted that the MPGs have improved.

    A word of caution... if you have warranty remaining, GM may use it as an excuse to not honour the warranty.
    Last edited by RayVoy; 06-24-2012 at 05:42 PM.

  9. #9


    CAI would help it some, Headers, exhaust, like some of the guys mentioned, a PCM. But if youre gonna spend that much money, go with the supercharger....turbo on a truck? could work but..meh

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  10. #10


    Several things can be done to your 4.8L truck. LT headers, custom tune, shorter gears, higher stalling torque converter. Next would be a Cam or Nitrous. Next would be some kind of boost, Supercharger or Turbo.

    Just a muffler and CAI is not going to add much power, you are looking at 10-15hp max.. Long tube headers are a good idea with a free flowing exhaust + a custom tune. Those 3 in combination will wake the truck up a bit, but it still wont be a race truck.

    You do know that a 278mm 3000-3200rpm torque converter alone with a custom tune will lower your 1/4th mile times by .3 - .4 on a stock truck.

    So if it were my truck and you didn't want to get into the cam territory yet I would do this..

    LT headers, free flowing exhaust, Custom tune. When you want more after that look into a 278mm higher stalling torque converter from like circled. They act like a stock converter until you floor it and then it wakes up a bit. You can daily drive a 278mm converter just fine daily and they are not aggressive. Only thing you might want to get with the 278mm is a bigger tranny cooler like a tru-cool 40k.

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