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Exhaust Question

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by bigoltrux77, Oct 30, 2002.

  1. bigoltrux77

    bigoltrux77 1/2 ton status

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    Right now im running a 400ci SB with Edelbrock carb and manifold,Hedman Headers, 2.25" pipe out to 2 Flowmaster 4 series. Im planning on changing that set up. I want Hooker Competition Headers with 2.5 -3" pipe back to 2 Flowmaster 50 series. Will that sound ok? What should i do. The 40's are too loud and the pipe is rusting, plus the headers suck. I want a whole new set up. What will the cost of the pipe cost me? I want about 3" straight back and then cowboy cut (/ \) out the back end. Thanks alot! /forums/images/graemlins/k5.gif
     
  2. Shaggy

    Shaggy 3/4 ton status

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    <font color="green"> 3" duals is way too much pipe for a small block if you want any kind of low end torque at all. Stick with the 2.25 if you stay dual, 3" is fine for single. You may be able to save some money and reuse the headpipes that's already in there, just have it cut off at the mufflers, put on the new mufflers and your tailpipes. </font color>
     
  3. TorkDSR

    TorkDSR 1/2 ton status

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    the backpressure will come from the muffler, pipe diameter has a little less to do with with it, imho.
    ryan
     
  4. Shaggy

    Shaggy 3/4 ton status

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    <font color="green"> I disagree, most quality mufflers flow pretty dang well, regardless of how much noise they produce. Dual 3" pipe with a 50 series on each side is way to much flow. </font color>
     
  5. MudNurI

    MudNurI 1/2 ton status

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    I don't agree with you.... I have 3" true duals.......the truck "low end" hasn't changed since they were installed. The previous owner is a good friend of mine, and I drove it back when it was first lifted, and that was before the duals.

    How much low end should I even have considering its a 305...you won't lose enough to make it noticable....more often that not, you'll feel a bit peppier...

    Brandy
     
  6. Shaggy

    Shaggy 3/4 ton status

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    <font color="green"> Well, it's a 305... I mean, you can't polish a turd... /forums/images/graemlins/rolleyes.gif /forums/images/graemlins/wink.gif How are you going to lose low end when you didn't really have much to begin with? /forums/images/graemlins/grin.gif

    I know that I'm not ouit in left feild here, but I don't have the engineering knowledge to back up my claims, just real world experience. Maybe someone smarter than me can explain why you lose low end torque with larger diameter pipe. /forums/images/graemlins/thumb.gif</font color>
     
  7. TX Mudder

    TX Mudder 1/2 ton status

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    Go with corvette exhaust manifolds.
    I did and got Flowmaster 50's, 2.5" true duals.
    Nice.
    -- Mike
     
  8. Can Can

    Can Can Pusher Man Staff Member Super Moderator

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    Listen to Shaggy- don't go bigger than 2 1/4 with performance mufflers.......
     
  9. Z3PR

    Z3PR Banned

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    Hooker Headers !!!!!!!! /forums/images/graemlins/thumb.gif!!!!!!!!!! /forums/images/graemlins/thumb.gif!!!!!!!!!!
     
  10. BowtieBlazer

    BowtieBlazer 1/2 ton status

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    if you are going 3" into a single muffler and out either 2.25 or 2.5 you should be fine.. 3" in and out the back will burn up some valves pretty quick...the back pressure gives you a bit more torque. General rule of thumb, bigger pipe alows for more HP which is gonna usually be closer to to top end....midrange pipe 2.5-2.25 is gonna be a good balance of torque from back pressure to the motor and HP from better free flowing than stock. Also more HP and less torque means more gas spent off the line getting going.... I have run a 40 series with turn downs....nice HP, when i added the rest of the 3ft out the back in 2.5 with tips made a world of difference, I could feel and hear the back pressure difference..pedal seemed a bit stiffer and engine idled loads smoother. On my blazer i went 1 in 2 out 3" from the headers all teh way through the high flow cat into the 50 series delta flow and dual 2.25 out the back...big differnce in flow from the 3" into dual glasspacks, out 2.5...

    I guess what it boils down to is how your engine is built....if its fairly stock (not a race engine or BB) 2.5 serves all your needs fine
     

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