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Subaru 2.5 Exhaust

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  • Subaru 2.5 Exhaust

    I need to design / build / reverse engineer / an exhaust for my machine.

    Any ideas or thoughts ? How about the cheapest places to buy the SS tube & bends ?

    My 2.5 has 2 O2 sensors..... Where do you think these should be placed ?
    Attached Files
    Happy Flying, Chris S.

  • #2
    Try Jegs.com , or summitracing.com for the bends. I've also found them on amazon. The 02 sensors should be no closer than 6" from where the pipes exit the head but try to get them within 12". There's quite a bit of info on the 2.5 liters.
    Bobby Munroe
    Private Pilot (SEL)
    PRA Chapter 62 #42748
    EAA #1160523

    Comment


    • #3
      I have always used JEGS and I use regular steel tubing not stainless steel,and I gas welded the joints.My engine is turbocharged and the exhaust tubing also supports the weight of the turbo,and

      is still in good condition after 700 plus hrs.


      Best Regards,
      Eddie Sigman,Polvadera,nm
      (575) 835-4921

      Comment


      • #4
        When I need an exhaust for my Yamaha 3cyl, I got it from Stainlessheaders.com. They send out a kit of lockable elbows and you use them and pvc pipe to mock up your exhaust. You send the mock up to them and they send you back welded stainless headers.

        I went and looked at their web site and found this picture of the header they made for me.

        http://www.stainlessheaders.com/three

        FWIW
        Jason O
        Last edited by Jason O; 05-17-2017, 07:53 AM. Reason: added additional content

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        • #5
          Thanks guys, Jason I really like that site.

          If I have 2 O2 sensors......One in each side ? at least 6 inches from the head ?
          Happy Flying, Chris S.

          Comment


          • #6
            Originally posted by CLS447 View Post
            Thanks guys, Jason I really like that site.

            If I have 2 O2 sensors......One in each side ? at least 6 inches from the head ?
            Yes, one on each side, or use just one about 6" after the pipes merge.
            Bobby Munroe
            Private Pilot (SEL)
            PRA Chapter 62 #42748
            EAA #1160523

            Comment


            • #7
              I found some cool stuff on the net.....https://www.amazon.com/Subaru-Imprez.../dp/B00JA1C4MM
              Happy Flying, Chris S.

              Comment


              • #8
                These gotta be lighter than Supertrapps..........I wonder if they work ?

                http://www.stainlessheaders.com/racemufflers
                Happy Flying, Chris S.

                Comment


                • #9
                  My exhaust ...prop set for 5250......

                  Changed exhaust to borrowed Groen bros......Supertrapps. Lost almost 1000 rpms.

                  Moved H2o temp sensor to better place......

                  VW Rabbit Rad......so for it is doing a great job ! Will it be enough ?
                  Attached Files
                  Last edited by CLS447; 08-05-2017, 05:14 PM.
                  Happy Flying, Chris S.

                  Comment


                  • #10
                    See if anyone has interest....why would I lose 1000rpms ?
                    Attached Files
                    Happy Flying, Chris S.

                    Comment


                    • #11
                      Originally posted by CLS447 View Post
                      See if anyone has interest....why would I lose 1000rpms ?
                      I suspect the exhaust is not working well in your application.

                      Go back to your other exhaust and see if you find the lost rpm.
                      Regards, Vance Breese Gyroplane CFI http://www.breeseaircraft.com/

                      Comment


                      • #12
                        Vance , I did reinstall my temporary exhaust.....they are back ! What would you say would be the best for a 2.5 Subaru ?
                        Attached Files
                        Happy Flying, Chris S.

                        Comment


                        • #13
                          Originally posted by CLS447 View Post
                          Vance , I did reinstall my temporary exhaust.....they are back ! What would you say would be the best for a 2.5 Subaru ?
                          I have no experience with a Subaru EJ25 so I can't help you. If you lose 1,000 rpm by changing the exhaust I suspect it is not the best exhaust for that engine.
                          Regards, Vance Breese Gyroplane CFI http://www.breeseaircraft.com/

                          Comment


                          • #14
                            Yeah, that's what I was thinking .

                            4 into 1s (4 cyl) and dual 3 into 1s (6 cyl) dont require a muffler in the system, this is due to the long length of primaries from the exhaust flange to the start of the collector (typical 28 -36) this long run of primaries along with the collector and tailpipe provide a muffling effect on the exhaust pulses. Some overseas customers will require additional Db reduction which can be provided by adding an additional muffler just past the collector. The HP increase due to the collector style exhaust will be reduced slightly with a muffler but Db reduction will be what is needed for overseas operators. With a collector style system the cabin heat is pulled off a straight primary section which provides high temperatures for good cabin heat. Since the primary is made from 321ss the high temps will not hurt the tubing under the muff. In aircraft that are known to operate in cold conditions we can also add heat pins to help pull heat from the primary to get even more heat for cold climates.
                            Happy Flying, Chris S.

                            Comment


                            • #15
                              So you have no exhaust knowledge at all that could be used for all engines ?
                              Happy Flying, Chris S.

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