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Old 09-19-2017, 02:44 AM   #21
KBA
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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!
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Old 09-19-2017, 04:16 PM   #22
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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.

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Old 09-21-2017, 03:11 PM   #23
KBA
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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 at 03:18 PM.
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Old 09-21-2017, 05:14 PM   #24
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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.
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Old 09-22-2017, 07:54 AM   #25
KBA
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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!

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Old 09-26-2017, 07:19 AM   #26
KBA
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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.




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Old 09-26-2017, 12:40 PM   #27
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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!
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Old 09-26-2017, 12:56 PM   #28
Bunta
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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?
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Old 09-26-2017, 02:47 PM   #29
KBA
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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...

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Old 10-08-2017, 05:48 AM   #30
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...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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Old 10-09-2017, 02:53 AM   #31
KBA
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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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Old 10-09-2017, 07:55 PM   #32
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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 at 07:57 PM.
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Old 10-10-2017, 07:51 PM   #33
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Man, maybe I do need to get my master's degree! You are doing some really interesting things.
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Old 10-12-2017, 05:56 AM   #34
KBA
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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 at 05:59 AM.
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