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Exhaust questions...

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by solowookie, Mar 31, 2001.

  1. solowookie

    solowookie 1/2 ton status

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    I just ordered and received new headers for my truck. They are hooker equal lenght super competition headers...

    Next week I am replacing the exhaust as well. I live in Wyoming where we don't have emmissions.

    I am going to pull my cat. converter and put in dual exhausts straight off of the headers. I have 2 questions;

    1. How do I handle the o2 sensor situation. I've seen o2 simulators for other vehicles...

    2. What pipe diameter should I go with, and what kind of mufflers. I want the torque increase ratio slightly higher then the hp. I also want something that sounds mean, but won't drive me crazy listening to it in the cab.

    Thanks for the great info...

    Jeff
     
  2. bigerik

    bigerik 1/2 ton status

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    I used 3" pipe on both my trucks before I found out that I should have gone with smaller pipes in order to maximize bottom end torque, so I guess think about 2 1/2" or maybe less. <A target="_blank" HREF=http://www.bigerik.coloradoK5.com>http://www.bigerik.coloradoK5.com</A>. 3" pipes sure look cool, though (I have a pic on Photo page 5 on my website). I put in an H-pipe (balancer tube) that also serves as a driveshaft loop.
     
  3. Scooter

    Scooter 1/2 ton status

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    I can't help you with the O2 sensor. So far as the exhaust tubing dia. as I understand it, if you stay with a single exhaust then 3" is the way to go but if you want dual exhaust then you'll want to stay with 2.5" or maybe even 2.25". I had a local shop build a cat-back dual exhaust on my stock 87 K5 using 2.25" tubing and a glass pack. Not too loud and it did seem to increase the pep of the truck.

    <font color=blue> Duct tape the small stuff down. </font color=blue>
    Scot in KC, MO.
    Black 87 Chevy K5
     
  4. HarryH3

    HarryH3 1 ton status Author

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    You can just weld a threaded bung into one of the header collectors so your oxy sensor will still work. That will keep your EFI working correctly.

    <font color=black>HarryH3 - '75 K5</font color=black>
    <A target="_blank" HREF=http://ThunderTruck.ColoradoK5.com>http://ThunderTruck.ColoradoK5.com</A>
     
  5. Twiz

    Twiz 1/2 ton status

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    Yes, a threaded bung to one of the pipes. I bet summit or someone like that would have what you need. I gotta buddy with a 'letric Q-jet and headers and says it works fine.
    I remember another post on this from some time ago, do a search for it.

    Twiztid
     
  6. muddin4fun

    muddin4fun 3/4 ton status

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    I've got headers and 2 1/2" pipe (true duals) and 50-series Flowmasters and I wouldn't change a thing! It just sounds nice when you're driving it and you can just barely hear it under normal driving conditions until you mash on it. It sounds great!!!! The sound it makes sounds like open headers just not so loud.

    [​IMG]


    <A target="_blank" HREF=http://muddin4fun.coloradok5.com>http://muddin4fun.coloradok5.com</A>
     
  7. CaptCrunch

    CaptCrunch 1/2 ton status

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    Flowmaster sells a collector that bolt on to the headers w/ an O2 bung... that will be my plan of action I think. You can see it on their website (they are owned by Holley).

    [​IMG]
    1987 Chevy K5 Blazer- 350 TBI
     
  8. solowookie

    solowookie 1/2 ton status

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    One other question. I am considering have the exhaust exit with slanted tips just before the back tires. I don't know how exhaust lengh would effect everything else, and if this would be ill advised.

    Thanks everybody for all of the feedback. I've posted on truckworld.com and off-road.com. Man, This site is so much better.

    I never gotten addicted to message boards before, but I think I easily could here. And the advice seems to be very will informed!

    I've had my Blazer about 2 weeks. I traded and 85 S-10 for it (that thing was beat to death). It had a LOT of work that needed done on it.

    This 89 full size is great. Cost me my S-10 plus $2000.00. There is a little body rust, but floorboards and everything else is in perfect condition. The only rattle the vehicle has is the stuff in the glovebox!

    Anyway, this is my new hobby. I need a good stress reliever to work on after work. I have a very techinical and high stress job. I REALLY need an after work project.

    Anyway, thanks for all of the great tips. I'll have to talk to my exhaust man and make sure he has the bungs etc. before I take my truck in.
     
  9. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Apparently having the exhaust exit before the rear tires is illegal...(right Lara???[​IMG]) I had mine exiting there and quite honestly it was annoying.

    Rene

    [​IMG]<A target="_blank" HREF=http://jules.coloradok5.com>http://jules.coloradok5.com</A>
     
  10. muddin4fun

    muddin4fun 3/4 ton status

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    It would be illegal to exit the exhaust in front of the tire. I'm looking at this from a safety inspector's point of view. The exhaust has to exit behind where passangers sit. It would fail a visual inspection (meaning even if you live where they don't stuff that sniffer up your exhaust pipe). If you like to run with your top down, then I would not advise running the exhaust in front of the rear tire. Besides, I think it looks stupid...just my opinion.

    [​IMG]


    <A target="_blank" HREF=http://muddin4fun.coloradok5.com>http://muddin4fun.coloradok5.com</A>
     
  11. solowookie

    solowookie 1/2 ton status

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    well, I think that settles it then... Definately no exhaust exiting before the rear tire. That all definately makes sense, and doesn't sound very safe.

    Thanks for the advise.

    Jeff
     

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