Announcement

Collapse
No announcement yet.

Exhaust System Size - 2 1/4" or 2 1/2"?

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Exhaust System Size - 2 1/4" or 2 1/2"?

    I am in the process deciding on the exhaust for the 79 C-10 LS swap. I have these headers:

    Click image for larger version

Name:	IMG_5453.JPG
Views:	208
Size:	226.1 KB
ID:	1263571

    Click image for larger version

Name:	IMG_5454.JPG
Views:	225
Size:	209.3 KB
ID:	1263570
    Chris - HRPT Long Haul 03, 04, 05, 13, 14, 15,16 & 18
    74 Nova Project
    66 Mustang GT Project

    92 Camaro RS Convertible Project
    79 Chevy Truck Project
    1956 Cadillac Project

  • #2
    I have these picked out for converters:



    Click image for larger version

Name:	Converter.jpg
Views:	216
Size:	47.1 KB
ID:	1263573
    Chris - HRPT Long Haul 03, 04, 05, 13, 14, 15,16 & 18
    74 Nova Project
    66 Mustang GT Project

    92 Camaro RS Convertible Project
    79 Chevy Truck Project
    1956 Cadillac Project

    Comment


    • #3
      The header collectors exit at 2 1/2" as do the converters. I'm wondering if I should go with 2 1/4" or 2 1/2" from there back. Please share any thoughts you might have. Thanks,
      Chris - HRPT Long Haul 03, 04, 05, 13, 14, 15,16 & 18
      74 Nova Project
      66 Mustang GT Project

      92 Camaro RS Convertible Project
      79 Chevy Truck Project
      1956 Cadillac Project

      Comment


      • #4
        I don't know the details but the engineers I worked with were sitting around BSing (in my test cell control room!) and they claimed that you CAN have too little back pressure. Guessing you could Google that? Not sure that 2 1/2" would cause that. As a practical matter it's probably more dependent on fitting the tubes thru the chassis and you likely have plenty of room.

        Dan

        Comment


        • #5
          Well my - 2 1/2

          You didn't mention mufflers - what are your thoughts on those?

          Comment


          • #6
            3" if you want a really throaty exhaust.

            only 2 1/4 if you are doing a sleeper.

            Comment


            • #7
              anything over 300hp=2.5",
              over 550hp needs 3".

              if the 3" is too noisy run resonators
              or inline short glasspacks in addition
              to mufflers.

              Comment


              • #8
                This was always a go-to system for my square bodies back then...http://www.heartthrobexhaust.com/1014144.PDF
                Patrick & Tammy
                - Long Haulin' 2008, 2009, 2010, 2011, 2012, 2014...Addicting isn't it...??

                Comment


                • #9
                  At the least 2½ to the muffler and 2¼ tailpipe, personally for myself 2½ all the way.
                  Pt 2010, Long Haul 2011,12,13,14,15,16,17, 18, 19, 23
                  If you wait, all that happens is that you get older

                  Comment


                  • #10
                    2 1/2 and 2 1/4 tailpipes should be fine. You can go bigger if you want, you probably won't gain anything noticeable. Modern trucks use 3" single exhaust with those engines, eh?
                    My fabulous web page

                    "If it don't go, chrome it!" --Stroker McGurk

                    Comment


                    • #11
                      whatever fits. If you can get 2 1/2 all the way back, do it, if not, 2 1/2 between the header and the cats should help with torque because it lengthens the collector....
                      Doing it all wrong since 1966

                      Comment


                      • #12
                        I have 2 1/2" tail pipes all the way with a crossover behind the headers on my '80 Chevy 3/4 ton with 4WD and they fit just fine even with the transfer case. The crossover pipe give you a little more low end torque and quiets the exhaust down some. If I didn't to deal with the transfer case I'd have 3" tailpipes all the way back. The theory of not having enough back pressure on gas engines was proven wrong long ago.

                        Comment


                        • #13
                          The o/p didn't say, but are the tail pipes going over the axle, or just exiting in front of the rear tires.
                          The part I never could understand, and never have had my hands on, to look at.
                          But it looks like those x pipe things, the center of the x is no larger than the pipe. So a 2.5" pipe, two of them, forcing exhaust through the center of the x that is 1/2 the area of the 2 pipes feeding it. Seems to me it be a bottle neck.
                          But again, I've never had one in my hands to look at. only seen photo's of them. So I might be way off.

                          Comment


                          • #14
                            Thanks for all the feedback. I'd love to have a custom job done but I have this from the Mustang project and should probably at least try to use these. It's 2 1/4".

                            Click image for larger version

Name:	IMG_5515.JPG
Views:	172
Size:	225.5 KB
ID:	1263659
                            Chris - HRPT Long Haul 03, 04, 05, 13, 14, 15,16 & 18
                            74 Nova Project
                            66 Mustang GT Project

                            92 Camaro RS Convertible Project
                            79 Chevy Truck Project
                            1956 Cadillac Project

                            Comment


                            • #15
                              The theory of exhaustion is not only the Hot gases going out, but MORE of the "Sound Wave" that creates a vacuum, also this frequency goes out then immediately races back up the system, and the cycle repeats with each cylinder. Hence the tapered megaphone tail pipes enhance this sound waves. Think about it, what's the theory of all header pipes being the same length. And the "H pipe" is equalizing two 4 cylinder engines in one system.
                              take a look at some of the High Dollar Indy, Grand Prix cars "Pipe Organ Octopus" systems.
                              It's free horse power.

                              Comment

                              Working...
                              X