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PT3 under research

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    #16
    Just tested the Delta 272 grind, based on the information found here:
    http://cb7tuner.com/vbb/showthread.php?t=96224
    The RPM ceiling stays the same, with just a slight suspicion on exhaust valve toss, but I need much more accurate specification to be sure of that.

    In the meantime, I still have a bit of food for thought to throw around here, but for that I am wondering if anyone has measured the F22A6 intake and exhaust runner lengths? Any help would be appreciated.

    Comment


      #17
      Haven't posted anything in a while, I was busy finishing off the supermoto season..
      Well I am not sure how many of you are still interested in this, but I have been experimenting with CFD on the PT3 intake ports. As I posted before, I have run the analysis on 28" H2O pressure drop with a grid density that should give me fair enough results and reasonable calculation time. What I found was approx. 310 CFM @ 0.550"lift on stock 34 mm valves. Now this might be a bit high compared to flow bench results that have been posted all over the net but this has at least three reasons:
      1) CAD surfaces are texture-free, as if the head was polished with just a slight roughness
      2) CAD surfaces are really smooth and don't include every tiny obstackle that might throw off the reading in real life.
      3) The flow bench itself is not included in the geometry so the results are not affected by it.
      Like I already explained, think of this result as a port that has been cleaned and polished to the slightest detail.

      What I experimented with next was larger valves (36 mm) on the same exact port. I also opened up the valve seats by 2 mm and adjusted the surrounding port area to blend to this opening.
      The result shocked me...





      To be honest I am not sure if there was a magnetic storm that threw off my CFD solver or something else went ballistic, but I repeated this several times and the result still stands. I scored a whopping 419 CFM @ 28" H2O and 0.550" lift on otherwise stock, cleaned port. After removing the valve guide stems I gained another 9 CFM.

      I am still not entirely sure this was accurate, but my CFD settings should be rock solid by now. Either way, it just goes to show you how choked this head is with stock valves and suggests that there is definitely something worth investigating in the overall layout.
      Last edited by KBA; 09-18-2017, 04:48 PM.

      Comment


        #18
        The PT3 head DEFINITELY has significant flow capabilities. As much as I dislike Bisimoto for his business practices, he was the first to really bring that to light. Properly ported, the head can supposedly flow as well as many far more performance-oriented heads.

        That being said, it's really great to see someone digging into it and showing how and why that is! Bisi would just talk down to anyone that questioned him, so few people learned anything from him.

        Thank you for sharing your findings and knowledge!






        Comment


          #19
          this is unreal!!


          - 1993 Accord LX - White sedan (sold)
          - 1993 Accord EX - White sedan (wrecked)
          - 1991 Accord EX - White sedan (sold)
          - 1990 Accord EX - Grey sedan (sold)
          - 1993 Accord EX - White sedan (sold)
          - 1992 Accord EX - White coupe (sold)
          - 1993 Accord EX - Grey coupe (stolen)
          - 1993 Accord SE - Gold coupe (sold)
          Current cars:
          - 2005 Subaru Legacy GT Wagon - Daily driver
          - 2004 Chevrolet Express AWD - Camper conversion

          Comment


            #20
            KBA,

            Would it be possible do hemholtz resonance intake tuning, say for ITBs, using that program? Rather, could it spit out a formula or set of numbers to find the best runner length and style(tapered, cylindrical, etc.)?

            Your skills and patience are incredible, btw.

            YouTube Clicky!!

            Comment


              #21
              deevergote,

              Just recently I have stumbled upon a racing team called "KPO motorsports" and their all motor CRX. Turns out they are also running F22A and on their way to follow Bisi's footsteps. Too bad they are not Americans (at least so it would seem), which means that there is almost no (for me) readable information on internet other than a few videos on youtube with 1/4 mile runs and pictures on facebook. Looks like they have already reached 360 whp range, I will make sure to follow their progress.

              sonikaccord,

              Actually I am using another program for this very purpose. It is using CFD or flow-bench data in order to calculate the effects of runner lengths and almost any other spec of four stroke engine. I can run the calcs if you like, but it will be of most benefit if you could list up the specifications of your engine. For example:
              - head mods
              - cam specs
              - current runner lengths and diameters (intake + exhaust)
              - bore x stroke
              - rod length
              - static compression ratio

              The result of all this will depend on the accuracy of the data that you provide. And of course let me know your desired peak power RPM. From my experience tapered intake runner will give you more area below the curve at the expense of peak power, and cylindrical runner, or one that does not change the cross-sectional area over length will do the opposite (provides the most ramming effect).

              As for the CFD,

              I am getting a little worried that with 36 mm valves, this thing might flow a little too well for any displacement H or F series engines are capable of running at reasonable RPMs, meaning that the flow velocity could be improved. This might also be one of the reasons why PT3 head is known to respond to mods not as good as other engines (at least what I have read). You would have to go all out to take advantage of the design, which is what Bisi did and KPO are doing now.
              I plan on doing some more experiments with flow simulations, but this time I will focus on not removing the material, but adding it. We can always use epoxy for this kind of work. I will be expecting still astronomical CFMs with an overall smaller port, meaning that average flow velocity has been increased, which should in theory make quite a big difference in performance.
              Stay in touch!

              Comment


                #22
                Slowly initiating some progress here. I am now in the process of building a CAD model that allows me to easily control the shape of the port by adjusting these projection splines. I have another set of those projected on the top plane to control the width. It will then update the surfaces to adapt to the new shape.
                Based on my experience from previous CFD + CNC porting operations, this combination of longer short side radius (floor) and shorter long side radius (roof) should yield me better CFM readouts with a smaller port volume. I guess we will find out when the model is complete and sims finished.

                Comment


                  #23
                  I still have not finished the new port design or run the sims, but it is in process. Just taking a lot more time to complete than I expected.
                  In the mean time I have something else to show you all. I have finally pieced together all the data necessary to re-create a stock F22A6 dyno chart in my laptop. In essence - I have now got a virtual F22A6 that I can dyno at any time, with any mods.

                  - Short block: specs by "The official H/F piston/rod/crank/block specs and CR thread"
                  - Head: scanned & measured by me
                  - Compression ratio: by zealautowerks.com
                  - Intake system: thanks to aventari
                  - Cam / valvetrain: scanned & measured by me
                  - Exhaust system: a rough estimate (maybe somebody will respond with precise measurements of stock F22A6 header tubes - length and diameter)

                  Fuel: 93 octane pump gas
                  Ambient conditions: according to SAE



                  According to advertised numbers, this should be quite close. Wait till we start dropping in some virtual parts
                  Last edited by KBA; 09-21-2017, 03:18 PM.

                  Comment


                    #24
                    I'm so stoked to see what actually comes of this project that you are working on. This is some very cool stuff that you are doing for our community. All of this information is going to be a goldmine in the future. I commend your effort and time that you have put into this project for all of us.
                    MRT: 1993 Honda Accord SE Coupe (Lola)

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                      #25
                      Thanks Rilas!

                      Today I found this pic on google. It is said to show H22A in cross section. I found it interesting to introduce this image in CAD software and overlay with my scanned PT3 (F22A) file.
                      I must say, there are quite a few resemblances, yet the intake angles on the PT3 seem slightly different. The combustion chamber is not as deep which positions the F22 valves slightly lower, allowing a greater floor radius. The intake runner openings match perfectly, and the exhaust port is smaller and placed differently when compared to H22.
                      Let the image speak for itself!

                      Comment


                        #26
                        While I keep you all waiting for the progress of port mod CFD, I just thought this might seem interesting to some of you.
                        Since I am working in exhaust manufacturing company, I have to fill my free moments somehow every now and then, and I've been doing that by designing a killer header for the F22. It incorporates stepped primaries and should hit pretty hard @ 7800 RPM. Nevertheless, it is still in design phases and some of the things that must still be done are primary length matching to a higher degree and addition of secondary steps. Then it's 4:1 collector, which I already have designed to a certain degree and I can start talking with the guys at shop floor to fabricate the parts.




                        Comment


                          #27
                          Thank you for everything you are doing. This sort of research on a nearly 30 year old engine is just awesome to see and I'm sure it will help many at some point in the future.

                          I'm definitely interested in the header design you're working on. I was one of the many who was suckered into buying a Bisimoto header to not only be plagued with leaks, alignment, and fitment issues, but lack of performance (even though he says each one is tailored to a specific spec sheet provided by the end user, they aren't).

                          Thanks again and keep up the awesome research!
                          Click Image for CB7Tuner.com Beanies, Decals, & Keychains!

                          Comment


                            #28
                            Looks like that header is mounted on an H22 though (not that us Hseries owners would mind another option). Do you have something for the Fseries worked up or is the picture of it mounted just using a generic engine picture as an overlay?

                            Comment


                              #29
                              Jon, thanks!

                              Bunta, the engine picture is just an overlay to give some idea about the proportions. I used H22A since I was able to find this detailed split on google and these engines are virtually brothers to each other. The CAD prototype you saw was designed specifically for PT3 F22A head geometry using my scanner session files.

                              About the header: I just ran some quick 1D engine simulations of how this header might perform on stock F22A6 when it is complete. One thing that is definitely a must is free flowing exhaust. I used only estimates (150 CFM for stock exhaust system and 300 CFM for opened up system). If one was to use that header on a bone stock setup, he would lose 5 - 7 hp.

                              You can see how it performs similarly on the low RPM and starts to hit near the redline. The design itself is good to go up to 8000+ RPM, it is the stock cam that is seriously holding it back.



                              Meanwhile, the port design continues...

                              Comment


                                #30
                                ...and once again I have faced delays with this project. As it turns out, I went after a PhD in mechanical engineering and I will have to work on other projects in parallel. I will be developing a throttle body of unseen design and concept for my CRF450R supermoto bike with hopes that it could one day see some business. So.. sorry for that, but anyhow, the sims are now running with the new port shape, 36mm valves and cut guides. Here's a screenie

                                The results should be posted later today...

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