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Flowmaster 70's...they're big mofos!

Discussion in '1969-1972 K5 Blazer | Truck | Suburban' started by ak bandit, Oct 7, 2005.

  1. ak bandit

    ak bandit 1/2 ton status

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    They're 3" center in/center out. I paid $110 each. That's alot of cash for a muffler if you ask me! :( I called around locally and the cheapest place wanted $225 each! So I gladly ordered them from Jegs and choked down the $40 for shipping to Alaska. They weigh a little over 20lbs each. I think I'm going to end up doing what Yukon Jack did (kind of). Running 3" from the headers to the mufflers. And reducing to 2.5" after the muffler.

    [​IMG]

    [​IMG]
     
  2. Burt4x4

    Burt4x4 3/4 ton status

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    Thoes are even bigger than the 70s I started with...I got the BigBlock II series that have 2.5" inlet/outlet...same length just not as fat as the 3".
     
  3. ak bandit

    ak bandit 1/2 ton status

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    Yep, these are also the Big Block II series. If you dont mind me asking, why did you get rid of them Burt?
     
  4. steve_kibbe

    steve_kibbe 1/2 ton status

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    Geese, thats a big sucker. :eek1: :eek1:

    I love the sound of a FM though :bow:
     
  5. Burt4x4

    Burt4x4 3/4 ton status

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    Well I wasn't gonna but when I got my rig to the exahust shop and up on the rack the owner and I were trying to figure out the best routing...he offered to test fit a set of 50sieres just to see if it made a difference...well the 50s seamed to be a bit of a better fit for me so the owner said he would swap my 70s for the 50s if I wanted so I said sure why not..I wasn't dead set on running 70s so I didn't really care eather way.

    I think the 50s & 70s are very close for sound..I heard Greg72s first gen 396 w/70s and my 50s are very similar to his so.....
     
  6. vtblazer

    vtblazer 1/2 ton status GMOTM Winner

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    I just had the 50's pulled out and replaced them with the 70's.
    A mellower sound IMO.
    Got the BBII's also, same as yours, 3" in and out. :eek1:

    Good fit if you've got an 8ft bed. ;)

    2nd pair of flows I've bought, both 70 series for my big blocks.
     
  7. supersize75k5

    supersize75k5 OrganDonorRacing.com

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    maybe because im still young, but I have always had 3 inch headers, pipes and 3 inch 40 series.. :laugh:

    its always put a smile on my face, but I can remember not driving my blazer plenty of times because it was to loud for neighborhoods at night :(

    how much more mellow are the 70's?
     
  8. Yukon Jack

    Yukon Jack 1/2 ton status

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    Dang, that's a big muffler! Let us know how they sound. Can you get a sound byte once you install them?
     
  9. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    Here's a "refresher" for you YJ....Apparently you never saw this post....? :D

    OK.....Last July, I took my junk out to the middle of nowhere to a dyno shop that RJF suggested.... here are a couple clips of the "hard pulls" they did. Each vehicle went over 100MPH on the dyno......

    Hearing Swampers at 100+ is scary! Everyone in the shop took a few steps back from the machine as it was making it's pull.


    1st one:

    '72K5 - 396BBC/Thorley TriY Headers/ Flowmaster 70-series duals / 4.10s & 38's....you can see the "Detroit Locker effect" when the throttle lifts too! (6MB)

    http://www.norcalbigdawgs.net/bb03/pics/Dyno%20Day%20-%20K5%20Hard%20Pull.MPG




    and this (bonus footage!)....

    '72 Burb - 350SBC with cast manifolds and Walker Dynomax duals (12MB)

    http://www.norcalbigdawgs.net/bb03/pics/Dyno%20Day%20-%20Suburban%20Hard%20Pull.MPG





    Final results (I still can't find the dyno sheets, but there here somewhere) were that the K5 put down just over 300 Lb/ft of torque at the wheels, and the Burb (even with a smallblock!) put down 292!!! Talk about embarassing for the BBC!!!..... [​IMG]

    Enjoy!
     
  10. Yukon Jack

    Yukon Jack 1/2 ton status

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    They both sound great!
     

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