Announcement

Collapse
No announcement yet.

Head machined/ported

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

  • Head machined/ported

    In return for helping a buddy with a motor swap, his dad is willing to machine/port my head for really cheap or even free! In the process I'm going to replace the valve stem seals and springs etc. Will I notice a difference in this or is it worth it?

    EDIT: in the title I meant ported.
    Last edited by Mazdababy; 05-17-2010, 10:32 PM.

  • #2
    Originally posted by Mazdababy View Post
    In return for helping a buddy with a motor swap, his dad is willing to machine/port my head for really cheap or even free! In the process I'm going to replace the valve stem seals and springs etc. Will I notice a difference in this or is it worth it?

    EDIT: in the title I meant ported.

    If you haven't done anything else to the car.. then most likely NO.. but it would be useful if you plan to do something bigger later.
    1988 323 GTX--- The toy now :D
    2008 Mazdaspeed 3::SOLD ----- 1991 BRG NA8 Swap, Turbo::SOLD

    Comment


    • #3
      It does have a lot of miles and carbon build up. I would hope to see smoother idling, running and faster better throttle response as it would have better air flow. Am I wrong?

      Comment


      • #4
        Originally posted by Mazdababy View Post
        It does have a lot of miles and carbon build up. I would hope to see smoother idling, running and faster better throttle response as it would have better air flow. Am I wrong?
        The whole hot tanking/cleaning of the head will have a decent improvement to the car. The porting and polishing of the head won't do much for increasing power.
        1988 323 GTX--- The toy now :D
        2008 Mazdaspeed 3::SOLD ----- 1991 BRG NA8 Swap, Turbo::SOLD

        Comment


        • #5
          Originally posted by wildfire0310 View Post
          The porting and polishing of the head won't do much for increasing power.
          Agreed, even the NA heads flow enough air to work well, unless as Bryan mentioned, you're planning for a lot more power/boost down the line and the engine management to harness it. Then I'd recommend a set of stock sized Supertech valves or the like along with the work since it's already cracked open. The better work would to be to deshroud the valves and do some bowl-blending work, there are small gains to be had there as it cleans up the casting flaws. Some people will recommend port matching the intake manifold as well. I disagree as I researched and believe that it can create air flow reversion back into the manifold, which is bad. YMMV

          Originally posted by miata5620
          Eric's Garage ... You buy all the parts I tell you to and you will have a killer car... If you want other parts used your car will suck and it will cost you more...

          Comment


          • #6
            Originally posted by RotorNutFD3S View Post
            Agreed, even the NA heads flow enough air to work well, unless as Bryan mentioned, you're planning for a lot more power/boost down the line and the engine management to harness it. Then I'd recommend a set of stock sized Supertech valves or the like along with the work since it's already cracked open. The better work would to be to deshroud the valves and do some bowl-blending work, there are small gains to be had there as it cleans up the casting flaws. Some people will recommend port matching the intake manifold as well. I disagree as I researched and believe that it can create air flow reversion back into the manifold, which is bad. YMMV

            People have port matched heads and manifolds forever and a flow bench shows the improvements pretty well. That little gap isn't going to promote air to flow backwards into the manifold all by itself. You'd maybe experience that sort of thing with an aftermarket short runner manifold in combination with a high overlap cam profile..

            Also I have a stock 1.6 with the head port-matched, ported and polished intake and exhaust chambers and the combustion chambers blended, deshrouded and polished. No valve job, no re-seating, just reassembled. It was done in preparation for turbo, and I assumed to see no difference NA. After a quick test drive, not the case. Power above 3,000rpm was much stronger. The motor definitely responded positively to those mods. I'm not going to claim to have made a great deal of hp, but myself and others who I asked to drive the car agreed on how noticeable the difference was.

            A lot of people say the 1.6 stock flows plenty unless running boost or full NA build...I've never seen a NA built motor without an extensive overall head port and polish. Does that mean it wont make power until you add high compression light weight pistons? lighter rods? cams? etc. No, Its just part of the equation. It's going to flow air in and out of the combustion chambers more efficiently regardless.

            To the OP-
            Without knowing the exact condition your head was in, just having the valves redone will show you improvements. The Hot tank cleaning will help also. From my experience you will notice a different with a port and polish. Don't expect to spank up on everybody on the streets all of the sudden, but if the head work is done well you definitely can't complain about the price. I'd say talk to the guys at integral cams and have them match you up to a set of their aftermarket cams. After that, maybe some ECU tuning, and you'll definitely be seeing some strong improvements.
            Last edited by Erotomania; 05-18-2010, 07:20 PM.

            Comment


            • #7
              Back in the day I ported several heads and did a lot of flowbench and dyno work to validate.

              Not going to share but lets just say for a normally aspirated street engine gasket match is very very minimal and don't touch the port floor other than cleaning. Spend all your time on the roof. Shave to the bottom of the button and unshrouding helps a lot too.

              Randy
              92 Italia "Competizione Speciale". 91 BRG, '69 Corvette "Mojo". '14 F150 Coyote 5.0. Looking for something blue.

              Comment


              • #8
                Originally posted by Erotomania View Post
                People have port matched heads and manifolds forever and a flow bench shows the improvements pretty well. That little gap isn't going to promote air to flow backwards into the manifold all by itself. You'd maybe experience that sort of thing with an aftermarket short runner manifold in combination with a high overlap cam profile.

                Also I have a stock 1.6 with the head port-matched, ported and polished intake and exhaust chambers and the combustion chambers blended, deshrouded and polished. No valve job, no re-seating, just reassembled. It was done in preparation for turbo, and I assumed to see no difference NA. After a quick test drive, not the case. Power above 3,000rpm was much stronger. The motor definitely responded positively to those mods. I'm not going to claim to have made a great deal of hp, but myself and others who I asked to drive the car agreed on how noticeable the difference was.
                That's the problem, just because it's been done forever on other cars does not necessarily mean that it's the correct thing to do on a Miata, just like valve angle jobs. Our engines do not respond well to it and flow benching has shown that, there were threads on miataturbo showing the results from various members. Paul, Pat, and Travis come to mind immediately, they did things with the cylinder heads and intake manifolds that no one else was willing to do at the time.

                The intake manifold runners need to be smaller than the port. You're not going to increase the airflow by port matching, you're going to increase the volume, which results in less velocity and less torque. What you have done to your engine is not proof that port matching works any better or worse because of the other work you had done at the same time. It's more likely that you would have seen a better gain if you had not port matched the manifold.

                Like I said before, I haven't found one group that sees eye to eye on this, even after being shown charts and dyno graphs. I've also seen one modification work great on one particular brand engine that does nothing beneficial for another.

                Originally posted by miata5620
                Eric's Garage ... You buy all the parts I tell you to and you will have a killer car... If you want other parts used your car will suck and it will cost you more...

                Comment

                Working...
                X