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exhaust- dual versus single 2 1/4 versus 3"

Discussion in 'The Garage' started by justwhatido, Jun 15, 2004.

  1. justwhatido

    justwhatido 1/2 ton status

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    exhaust- dual versus single 2 1/4 versus 3\"

    After the headers it's time for exha /forums/images/graemlins/pimp1.gifust. I need an education. I see single cat-back and turbo flow exhaust systems that are 3". (What is a cat-back anyway?)and I see duals that are 2 1/4. What are the relative advantages and disadvantages of each? Why not dual 3" pipes?
     
  2. 6.2Blazer

    6.2Blazer 1/2 ton status

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    Re: exhaust- dual versus single 2 1/4 versus 3\"

    A single 3" exhaust will flow as good as dual 2.25" pipes. The advantage is that it is sometimes easier to route a single pipe than duals.....though sometimes not....

    A "catback" exhaust is a term used for an aftermarket exhaust system that replaces from the catalytic converter to the back of the vehicle. To technically keep the vehicle emissions legal you can't mess with the cat and hence how these systems came about.

    You can use dual 3" exhaust but you most likely don't need that much capacity unless you have something like a really built big-block.
     
  3. mrk5

    mrk5 The Sticker Guy Moderator Vendor GMOTM Winner Author

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    Re: exhaust- dual versus single 2 1/4 versus 3\"

    Flowmaster's recommendation:

    2" tubing up to 100 hp per pipe
    2.25" tubing up to 160 hp per pipe
    2.5" tubing up to 200 hp per pipe
    3" tubing up to 300 hp per pipe

    With a '73, you don't have to worry about a catalytic(sp) converter.
     
  4. Z3PR

    Z3PR Banned

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    Re: exhaust- dual versus single 2 1/4 versus 3\"

    I prefer dual exhaust over a single exhaust system.
     
  5. fortcollinsram

    fortcollinsram 1/2 ton status

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    Re: exhaust- dual versus single 2 1/4 versus 3\"

    I have dual 3" with Thorley headers...It is a bit too much exhaust, even for a mild 454 that gets romped on...for a 350, my personal preference is on dual 2-1/4".

    Single 3" is nice for routing reasons, esp. when you have lots of mods..

    Chris
     
  6. 84_Chevy_K10

    84_Chevy_K10 Banned

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    Re: exhaust- dual versus single 2 1/4 versus 3\"

    I'll trade ya anytime. I've got dual 2 1/4" on mine and it's nowhere near loud enough for me.
     
  7. 4xcrazy

    4xcrazy 3/4 ton status

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    Re: exhaust- dual versus single 2 1/4 versus 3\"

    I had dual 2.5" on my Nova with a 350 in it for awhile, then switched to a single 2.5" back to a single inlet dual outlet muffler (Hooker Areochamber) with dual tips, i personally think this current setup sounds better, and it didn't seem to change the performance of the engine or running habits much if at all. i didn't notice any anyways.

    Personally, i plan on installing a 3" back to a dual out muffler with dual tips out the back up against the sides of my trailer hitch.
     
  8. trailblazer86

    trailblazer86 1/2 ton status

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    Re: exhaust- dual versus single 2 1/4 versus 3\"

    I went with the 3" single exhaust.
    Headman headers 1¾” to 3” collectors.
    Collectors to 2½“ reducers.
    2½" pipes back to custom “Y” pipe into 3” cat and out the back with 3” pipe.
    I used a big honkin’ Magnaflow muffler that is a little too loud for my taste, but it is fun.
    I don’t think this system is really worth the expense as the engine will never see any more than 5500 RPM.
    Next time I will go for dual 2 ¼ “ with a balance tube and maybe some 3” pipes from the mufflers back.
    This is a truck and I want to keep the torque in the bottom revs.
     
  9. skelly1

    skelly1 1/2 ton status

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    Re: exhaust- dual versus single 2 1/4 versus 3\"

    I have 2.5" pipe with dual flowmasters on the 72 with the mild 396. It sounds phenomenal and the motor spins like a mofo up around 5000 RPM's. I was told that if you do 3" on a dual settup, your torque goes down, but I don't know the theory.
     
  10. imaginepro

    imaginepro Registered Member

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    Re: exhaust- dual versus single 2 1/4 versus 3\"

    I have a 3" flowmaster single exhaust with my 350, with Headman Ellite Headers and I love it. the sound is awsome and it has plenty of air flow I get great pro out of it. couldn't be happyer. /forums/images/graemlins/thumb.gif /forums/images/graemlins/thumb.gif
     
  11. socalblazer

    socalblazer 1/2 ton status

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    Re: exhaust- dual versus single 2 1/4 versus 3\"

    My truck appears to be similar to yours. I have a stock 350 and I use stock exhaust manifolds for simplicity. I just had a 2 into 1 system installed using 3" pipe and the Flowmaster Deltaflow big block muffler. I'm happy with the sound because it gives the truck a semi-performance sound without making me shout at my passengers, even w/the top off it's very tolerable. The only problem is that my bottom end torque has suffered compared to the original system. For a mostly stock 350 I would suggest a single 2 1/2" system utilizing a good muffler to keep the torque up and the sound good, duals are nice but I think those are better suited for performance vehicles that need to evacuate more in the top end. If you can, go to a cruise or event where you can listen to various exhaust systems and ask what they're running, then you can choose from there. Good luck! /forums/images/graemlins/thumb.gif
     
  12. 84_Chevy_K10

    84_Chevy_K10 Banned

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    Re: exhaust- dual versus single 2 1/4 versus 3\"

    Single 2 1/2 will choke a V8, even a stock one.

    Adding a 3" single exhaust did not cut your torque, and if it did, your fuel mixture is probably too lean. If it was tuned correctly it would certainly make more power.
     
  13. Smitty

    Smitty 1/2 ton status

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    Re: exhaust- dual versus single 2 1/4 versus 3\"

    I run a 3" single exhaust behind my 350 in the Blazer. It runs through a 3" cat to a 3" 40 series Flowmaster and exits behind the right rear wheel. I also run a 2.5" dual system behind the 383 in my 56 pickup and it exits behind each rear wheel. It has dual 40 series Delta-flow Flowmasters. I'm still getting used to the truck since I just put it on the road but I think I like the sound of my Blazer over the 56. As far as performance goes, there's no way to really compare the 350 to the 383 because of the different build levels....
     

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