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PT3 under research

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    #31
    The calculations are finally done, and I am a bit surprised. The flow rate went down the slope with the raised floor, shorter roof and 36 mm valves - 330 CFM. This leaves me curious about the port volume, if it is significantly smaller, then the overall efficiency might still be improved, but if the volume has not changed much, then I might suspect that the engineers that designed the PT3 head knew exactly what they were doing. Time to regroup and find another way at it. Maybe the characteristic of the Honda fourbangers really does prefer a longer roof like it is stated on some CNC porting articles. I guess we shall see!

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      #32
      What's your opinion on knife edging the port walls? I did that to my head last month when I did a mild port/polish job for my Lemons race car.





      I can't say for sure that the porting helped, but with the new head and port job and new rings the car definitely pulled harder on the top end and I was passing cars on the high speed straights that should have a lot more power in theory. I'm sticking with just the A6 cam though as reliability is paramount in endurance racing, and keeping the RPMs down is how you do it.

      Other than knife edging, I basically just cleaned up the casting and gasket matched the intake
      Last edited by aventari; 10-09-2017, 07:57 PM.

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        #33
        Man, maybe I do need to get my master's degree! You are doing some really interesting things.

        YouTube Clicky!!

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          #34
          Aventari,

          knife edging always helps! Sure it's not astronomical, but cleaning up the casting debris is a slight gain. None the less, it seems that these ports are already heaven from stock, just like Bisi said, the engine will only need a cam and compression. The only thing keeping the int. ports from going to the moon with CFMs are the narrow valve seats that score a flow rate equivalent to many great heads running bigger valves. Remember - I picked up almost 100 CFM @ .550 lift on my CFD analysis by swapping to +2mm valves and enlarging the seat throats. And on the exhaust side, I can tell you that exhaust ports are generally overrated. The thing that people ignore is that you have only so much of pressure differential on the intake (significantly below 14 PSI) but the exhaust sees thousands of PSIs when the valves open, making the exh. port CFM that much more insignificant than intake. Sure, it helps but nowhere near as drastically as intake. Besides, you don't want your gasses to escape the chamber too quickly, because it might screw up your tuning events. I remember once I did some experiments with increasing the exhaust cam lift on my bike, and believe it or not, but I actually lost power. The bottom line is: it all depends on your setup so bigger is not always better.
          I also built my bike for reliability because I cannot feed enough money into it if it has to be rebuilt every season. The one trick I did for that - I called WEB and asked them to list down the available profiles out of which I picked the ones that had the most duration while retaining low lift. The engine now runs a lot quieter than it did, and produces gobs more power. Sure, not as much as it could with high lift, but not very far from that. Low lift and long duration is key to happy valvetrain.

          Sonikaccord, I can only encourage you. Those studies sometimes open up a whole lot of possibilities
          Last edited by KBA; 10-12-2017, 05:59 AM.

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            #35
            Just so you guys wouldn't think I'm dead - still working on the PT3. I have done several more CFD sims, and the final results are as follows:

            Intake:

            Stock (cleaned) port with 36 mm valves (C32B), blended valve seats - 310 CFM @ 0.500 in @ 28 in H2O (with filled injector cavity, can probably score another 50+ CFM with this cavity present, but it does not function when the runners are installed. Bare in mind that CFM reading you see online are with injector cavity functioning as part of port entrance.)

            Exhaust:

            Stock port with 30 mm valves, blended valve seats and bigger entrance - 210 CFM @ 0.500 in @ 28 in H2O

            I think there is no need of "properly porting" this head. Just some basic operations because it is already awesome from the factory. The small valves are what chokes it.

            Right now I am hunting for some AMPCO 45 billets to machine my guides and seats, and then I will be shipping my cam to WEB for a custom hardweld + regrind.

            Meanwhile, I have mostly finished the CAD for my header. Check it out:

            ID42mm x L155mm + ID47mm x L300-500mm + ID42mm x L50mm + 4:1 collector + 67mm main pipe. The steps seem wierd, but in fact, they should extend the torque curve to the top of RPM.

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              #36
              I really admire your work! but wouldn't that choke the exhaust? Wouldn't it be better for torque to just use the 42mm throughout?

              Comment


                #37
                Originally posted by NolsAccord_CC1 View Post
                I really admire your work! but wouldn't that choke the exhaust? Wouldn't it be better for torque to just use the 42mm throughout?
                Well that's just the thing... I too once thought that it is important to keep the exhaust header uniform to maximize the speed of a greater volume of gas. But the deal with exhaust is never that simple. What is really important for the intake, is less important for exhaust and vice versa. While you want an unobstructed high speed flow at the intake side, exhaust couldn't care less. It cares more about the back-and-forth propagation of sonic (pressure) waves in the tubes which is determined by the changes in cross-sectional area A.K.A. tube diameter. By creating a stepped path, we can create wave reflection points. Stepping to a larger diameter reflects a negative wave, stepping to a smaller diameter reflects a positive wave. By adding these steps at the correct points, we can cancel out the waves when they are not wanted, and amplify them when they are of benefit. From what I have found, the greatest exhaust "sucking" effect can be found with longest possible tubes for the given RPM. This will have a downside however, it will virtually kill the torque in any other RPM. Using shorter tubes will broaden the torque curve, but it will not reach as high. Using steps in combination with longer tubes will give you the best of both worlds if done right. In this case, the larger section in the middle is used more as a damper or "resonator" to induce the wave interaction. My expectations are that torque will start mild, gradually increase along with RPM and die off very close to the power peak. Similar to what you would see with a centrifugal supercharger.

                Sorry for such a long write up but I can't think of another way to explain this..

                Comment


                  #38
                  No, thank you for your long write up One can never know too much.
                  For how much you think you can build this header?

                  Comment


                    #39
                    KBA, I'm curious as to how far out, you might be on actually making this header, and dyno'ing your setup?

                    I love everything that your doing for the community as a whole. I'm seriously interested in the results, due to everyone thinking the F22A/PT3 platform isn't worth even mentioning.

                    What are your thoughts about cam options? Are you just going to get a hardweld with high lift and such for the high rpm, or something that has a better torque curve?

                    I'm sure you have more than enough knowledge gained and forgotten in the engine building department than most of us will ever have even gained. You may want to read a previous members ride thread, as he pioneered a lot on the F22A/PT3 platform. Here is the link jdm92_accorn.
                    MRT: 1993 Honda Accord SE Coupe (Lola)

                    Comment


                      #40
                      NolsAccord_CC1,

                      Well, I am not sure really.. The laser cutting could cost about 20-30 Eur including material. The pipe bending could reach as much as 100-150 Eur including material as there are 4 pots X 5 bends = 20 bent pieces (each with about 50&#37; wasted material). The collector is sheet metal so the rolling might cost another 20 Eur. And then there is TIG welding. (TIG because I like my pipes to look good) This could be another 50 - 100 eur.

                      Add everything up and we are looking at 200 - 300 Eur as just cost-price. It could be done cheaper I guess but that would require higher quantities. The biggest problem are the bends. We have a zillion companies over here offering different pipe bends but they are all for construction purposes so the sizes are way off from what I need. The only option is to get them done at my employer but he is a pain in the... when it comes to anything other than serial production bringing big bucks. We shall see.

                      Rilas,

                      It is always nice to hear such kind words, thanks! Generally I do not like to think of myself as very much "experienced", I am simply an enthusiast with an open mind and endless curiosity.

                      The cam in my opinion is the reason why no one is considering this setup worth mentioning. It is virtually non-existent when compared to any other engines that are called worth-while, like H22. I usually get very mad when researching this stuff online, I see 99% of people judging engine's potential based on the number of cams and presence or absence of VTEC. The major thing that keeps the F22A back from cranking H22A like numbers is the cam. And it is not because there is only one, it is because the profiles are very short. There is no overlap. It barely lifts the valve in comparison. On the other hand, the base circle is bigger than H22A and the rockers have more leverage, this is again something that Bisi found. The valvetrain is setup the same way the head is. The potential is there but the small valves and cam are whats keeping it back. The regrinds that you can find are decent, but still not enough to really open that thing up. Personally I do not like regrinds because they cut down on reliability by decreasing the base circle and compromising the hardness.

                      About the torque curve, after having a closer look at the overall design, I think there really are better heads for reasonable torque curves, like the F23A. It has a smaller port that flows better at low lift which is ideal for strong low and mid torque. The F22A head, however, provides the opposite: large port that outflows anything at higher lifts. This is ideal for mid to top end torque and in my opinion one more reason why the engine lacks performance per displacement - it is set up for low RPM from the factory. So overall what you have is a professional sprinter put to weightlifting, a very good power-plant used for the wrong purpose. That's describing the F22A in metaphor. Personally I will be aiming my build to whatever the stock F23 block can safely withstand with lighter pistons, better bearings, ported oil pump and perhaps a block guard. Could be 7500-8000 tops, so I will be aiming at 6500 RPM peak torque and 7500 RPM peak power.
                      At the moment in cam specs that would be about 240/268 deg @0.050 and around 13/12 mm lift. The cam is practically made for such specs..

                      About the header, I think I will get it done, the question is when.. Since my hands are full at the moment I cannot pay full attention to anything I am doing, only here and then.. We shall see.
                      Reading through jdm92_accorn's post was the first thing I did when coming here. The same goes to Ghost and his blog
                      Last edited by KBA; 02-08-2018, 05:23 AM.

                      Comment


                        #41
                        Just finished a few more renderings to inspire my self getting to fabrication.
                        Enjoy.




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                          #42
                          If ever there was a reason to go back to an F-series engine your research and work would be among the top choices.

                          Comment


                            #43
                            Now this is good as gold! i wanna thank you for all the time invested in researching this motor and its byproducts.
                            No marathon gets easier later. ...

                            Comment


                              #44
                              Thank you and you're welcome to everyone.

                              Right now the head is at a local shop to remove the dead valve seats and guides. The process is slow and I have to keep calling them in order to make them remember about myself.
                              But in the meantime thought I'd clean her up a bit. All these years working on engines has thought me one thing - if you want things to perform and last, assemble them clean. A good workshop draws parallels to a pharmacy if you know what I mean

                              Starting with the rocker arms:
                              Left: diesel bath + soda gun
                              Right: diesel bath + soda gun + dremel brushing

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                                #45
                                And so, based on the CFD input, I had the feeling that port work might not even be necessary, simply because the PT3 is already so good from the factory. So I decided to simply install +2 mm valves, blend the seats and clean the casting with a sand paper. Before I do it all, I just wanted to throw up a last, clean flow sim on a port that would match my final result as close as possible. Here are some pictures of how and what was done in CAD to accomplish this.



                                The green areas point to the only changes that were made aside from the original.





                                Here the interference zones show a very close tolerance between the scan and CAD surface. Overall I think the resemblance is now a lot greater than it was initially.



                                Lets just say that I decided to go with shiny beryllium copper seats and bronze guides along with the bigger valves, so here is the final image.



                                CFD will follow next week.

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