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Dynomax or Flowtech Afterburners

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by SAVAGE1, Feb 7, 2001.

  1. SAVAGE1

    SAVAGE1 1/2 ton status

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    I need some pros and cons before I click the ORDER button.

    BLAZER FOOD!!
    [​IMG]
     
  2. ragtop

    ragtop Registered Member

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    I installed a set of Flowtech Afterburner hedders, along with 2 1/2 in duals exiting behind the rear wheels and 3 chamber flowmasters about a year ago on my 88 K5 350 TBI in place of stock cast iron manifolds and a 2 1/2 in single exhaust with some kind of turbo muffler (someone else had previously removed the cat). I did remove the air pump and air manifolds. I also bought and installed Flowtech's collectors with the Oxygen sensor bung welded in. The Flowtech's both went in from above and all I had to remove, then replace through the hedders, the dipstick on the pass side and all 8 spark plugs. Been a while but, I think that the instructions said I'd have to remove the starter although I didn't. I love them and have had no problems with the computer. Only mistake I made was using a pair of "Dead Soft" aluminum collector gaskets as they quickly worked (squashed) their way out of the top of the hedder / collector flange causing an exhaust leak on both sides. Replaced them with paper gaskets in late spring and have only had to retighten the hedders to the engine once. This gave the 350 a "significant" power increase throughout the engine's powerband ( about 1500 to 4500 rpm). I didn't check any acceleration times (though I wish I had so I could see just how much difference ) but the combination made a big "seat of the pants" difference. Still doesn't run like my 96 Z-28, but everyone who's been in it when I laid into the skinny pedal on the street can't believe that the engine's still stock (with 127,000 miles on it). I've since put on an open 14 in K&N, tweeked a bit on the TBI and just had the 700R4 rebuilt w/mild shift kit, and it won't, in my book, break the rears loose on the 1-2 shift, but it does more than just "chirp" em (gotta watch out though if the road's wet). If I had it to do over again, I'd do exactly the same.
    Hope this helps.

    Ragtop - '88K5 [​IMG]
     
  3. 90K5

    90K5 1/2 ton status

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    Hmmm...sounds like my decision's been made. I tested my acceleration times the other day, but not very accurate (I hope). I had a full tank of gas, and it may have been a little uphill. I have a 350 with power pulleys, chip, K&N, Flowmaster, Catco cat, TBI spacer, injector spacer, airflow enhancer, 33's and 3.42. By the count on my CD player (I just started the song as I floored it[​IMG]) I got about 11 or 12 secs. i am mostlyt chalking this up to the gears, which will be gone soon.

    90K5

    See my truck at <A target="_blank" HREF=http://albums.photopoint.com/j/Albumindex?u=1329584&a=9886502>http://albums.photopoint.com/j/Albumindex?u=1329584&a=9886502</A>
     
  4. CaptCrunch

    CaptCrunch 1/2 ton status

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    what brand tbi spacer you running? do you feel it was worth the money? Pondering the thoughts of one.

    1987 Chevy K5 Blazer- 350 TBI
     
  5. 90K5

    90K5 1/2 ton status

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    Hey Ragtop, did you have to replace the A/C bracket? Flowtech says I have to change it out. Do you have the serpentine belt on yours or the old system with several belts? I don't know if thta matters, but it might. Thanks

    90K5

    See my truck at <A target="_blank" HREF=http://albums.photopoint.com/j/Albumindex?u=1329584&a=9886502>http://albums.photopoint.com/j/Albumindex?u=1329584&a=9886502</A>
     
  6. ragtop

    ragtop Registered Member

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    Oh Oh, glad you asked (that's what I get for trying to think at 1am). I did have to grind off, using a side grinder the back bolt hole part of the bracket to clear the front header tube and then got a couple of spacers (those things that look like a nut that's about an inch thick, same type thing thats used on a cb antenna mirror mount to screw the antenna whip into except bigger in diameter) at the hardware store to make up for the space that the cast iron manifold no longer filled between the front bolt hole in the header and the front hole in the AC bracket. I also got a grade 5 bolt, about 3 inches long, of whatever size to fit into the front bolt hole (probably didn't need to be grade 5, but I overkill everything). I'll take a pic tomorrow and post it in case I've further confused you.

    Ragtop - '88K5 [​IMG]
     
  7. ragtop

    ragtop Registered Member

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    I had to go out and check the belts to be sure I got this right, continuing on...
    Mine has one serpentine belt around the crank, water pump, and alternator. It then has one V-belt around crank, water pump, a/c comp, and power steering pump. Another V-belt around the crank and power steering pump. And use to have another V-belt from the water pump to the AIR pump. A total of 4. That's part of why I took off the AIR pump. I kinda thought that was a real screwed up design.

    Ragtop - '88K5 [​IMG]
     
  8. K5Jimmy

    K5Jimmy 1/2 ton status

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    I run Ceramic Flowtechs on my 89...I cut off the rear of my A/C bracket...I run 3" pipes to HiFlo cats...2 1/2 pipe to Dynomax...2 1/2 pipe to pencil tips out the back...no crossover because I like the way the duals sound...definate seat of the pants difference...with the KN filter, I think this TBI is breathin' about as well as can be expected...installation was not a hassle, didn't remove the starter...the plugs are easy to get to, and I have had fewer gasket leaks than with the Hookers and Hedmans I have owned in the past... I like the pencil tips out the back, since that's the way Chevy's have been done forever, but I should have run them to just behind the rear and turned them down to exit the corner of the vehicle...I'll just wait til I crunch 'em up or get bored and change 'em .....overall, I'm happy with the combination I went with...in 3 yrs, the coating is holding up well, so I'm a happy guy...JD

    I'm at 10th and Plum....10 miles from nowhere, and Plum out in the sticks....Stuck?...Hell no..I still got some gas left..
     

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