MONZTER
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Posts posted by MONZTER
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Well, we have had some good comments about the excessive velocity and pressure numbers on the CFD plots. TurboBlueStreak was able to find a better way of testing it with more realistic numbers. We used a Excel sheet for turbo matching to calculate some flow numbers for different boost pressure and RPM. TBS says "all the test were done ignoring atmosphere pressure so inlet and outlet pressures where = to turbo outlet pressure the flow inlet was cubic feet per minute converted to cubic inches per second."
Here is the Excel sheet showing the flow numbers. The test number on the sheet relate to the CFD results below: Click on the picture to enlarge it from my gallery-
Here are the new results as well as some videos
test#1 1.5psi boost 2500 RPM 127 CFM
Test #3 5psi boost 3500RPM 214CFM
Test #7 20 psi boost 5500 RPM 581 CFM
Test #9 20psi boost 7500 RPM 793 CFM
Some videos of test #9
http://album.hybridz.org/data/500/Test_9_velocity.avi
http://album.hybridz.org/data/500/Test_9_velocity_b.avi
http://album.hybridz.org/data/500/Test_9_velocity_c.avi
So now you can see that as the flow and velocity go up, there is some crazy swirling going on in the plenum. It looks like 1 swirl is feeding each bank of runners. It also looks like the runners 1 and 2 are not getting balanced flow. Maybe a baffle inside will help, or maybe something in the plenum to disrupt the vortices.
I hope you find the new information and test data interesting. A big thanks again to TurboBlueStreak for his time in the CFD analysis.
So any new comments? Should I be worried about the results as they are?
Jeff
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Tim,
I PM'ed TurboBlueStreak who did the CFD work. Here is what he had to say: "Jeff as your question of how the cfd was run I ran the cfd with pressure openings. the runners were environmental and the inlet was 25psi. I'm going to review all my information and see if I can run the test in a better way. Hopefully we won't see extreme pressures or supersonic flow. "
So it seems were were correct with our assumption.
Here are the correct sizes of the model -
Runners at the head = 36mm ID
inlet into the plenum = 70mm ID
I will post anything new he runs
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Thanks Tony for the input, since I will have to make the weld fittings for the Wiggings clamps myself, I will just make them fit close together and no straps will be needed to keep them from moving.
Tim this it mounted in back on top, hood clearance is going to be close. I have it mounted on the V-band clamp/fitting that comes with the BOV. I like you ideas about integrating the bottom half into the plenum, but it will not be possible to machine it the way I have designed it to be made. I think I will have to resort to welding it on after the plenum is finished and installed in the engine compartment. I think this will be the safest bet:)
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That's what I was thinking too. That would definitely explain the pressures in the plenum and the high port velocities. If that's the case, I believe it could be easily remedied by adding a known restriction at each port and adjusting until the flow numbers look realistic.
Like the Wiggins clamp solution, btw. Sorry about the added expense...
:flamedevi:flamedevi:flamedeviTim, that was great advice. After your comments about getting to the screws I went and looked at it. I would need like 10" long fingers to get to some of them. I thought at first no big deal because I will just bolt the plenum on before bolting on the manifold. Then I realized, how am I going to balance the TB's without removing the plenum. Its funny how you get deep into a project and so focused on the details that you miss the obvious. This is why I like this forum so much, great people with tons of real world experience.
As for the added expense, It may actually be wash. I had to shorten the length of the air horns to make room for the clamps. The material stock size went down by a 1/4 of thickness, and that's a lot of weight and alot of savings when your talking a hunk of metal that big.
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What happens at the manifold/head interface in the sim? Is there any restriction modeled in at that point, or does it assume that the manifold is dumping to open air at that point?
It looks to me like the runners are dumping all at one time to open air. You can imagine how much air would have to be pushed through to generate pressure like that with open runners. This is just me guessing again, as I have very little understanding of the CFD software. Maybe TurboBlueStreak can chime in on the details.
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Tims Wiggins clamp Idea. I like it, I think I will go this way.
Still have not figured out how to integrate the BOV besides welding it to the plenum
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I kinda thought you might have already had that covered, just couldn't tell from the pics. Do you have an external boost controller, or do you plan on using the TEC3? Maybe leave yourself room to add one if you don't like the GPO control?
I plan on using the GPO control on the Tec 3. How are you running your vacuum lines? Are you tapped into the compressor or the plenum? How would the routing be different for a GPO control vs. an external? I have never looked into the external controller
Since I seem to be in the business of making your life more complicated tonight, what if you just used the diaphragm assembly from your TiAl and integrated the valve body part of it into the plenum? This might allow a bit more clearance (and would be slick as hell
)That’s a cool idea; I will look to see if I have room. The main problem is that the plenum will be made in two halves, surface machined in two operations normal to the seam line. This makes it difficult to get ports or details on the sides. I could always weld it in and blend it afterwards??
Oh - and have you considered either V-band or Wiggins clamps (stupidly expensive) for connecting the plenum to the throttle bodies instead of the bolt-on flanges? This is one thing I wish I could have done with mine - the bolts on the bottom side are a huge pain to get to. A nice quick release setup would have made the setup much more serviceable.
I am using Wiggens clamps everywhere else. I machine the flanges myself and only buy the clamshells (saves some money). That would make life easier. The thing I worry about is the expansion of the Wiggings clamps. They are designed to float and have about 1/4 inch gap between the flanges. I am not sure but I think when under boost the flanges might be pushed apart causing the plenum to have a lot of movement. Again maybe Tony D has some comments.
If you stay with the flanges, I had o-ring grooves cut in the throttle bodies so I wouldn't have to mess with gaskets...
Once again another good idea, do know how much money you are costing me today
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by back corner you mean that area of very high pressure near the rear cylinder, right? That looks like the perfect place.
how far away from the exhaust manifold would this plenum be situated? perhaps you can modify the back corner so there is a flange on the underside?
Yep that is where I was thinking. Tim had some good ideas that might help.
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On the vacuum ports integrated into the backside - I'd suggest leaving yourself a couple of spare ports - there always seems to be one more thing that you need to connect. You could just plug them with a nice anodized hex plug in the meantime.
Also, do you already have a solution for a compressor bypass? If you so desired you could integrate a flange for the bypass of your choice, or even design your own, integrated right into the plenum with a properly sized valve...
Hi Tim,
Thanks for the comments, good Idea of making a couple extra ports in the vacuum log. I currently have provided for in rail #1 the Air Idle Control, and the EGR. In rail #2 I have provided for the MAP, Boost gauge, Fuel pressure regulator, and the Compressor bypass BOV. Can you think of anything I am missing?, or some suggestion for future needs?
I really wanted to integrate the BOV into the back corner of the plenum tank (I have a Tial) but there is no room. I have pushed the engine back an inch and the plenum is close to the brake booster. My plan was to run it in the intercooler outlet tube in front of the core support, Do you have any suggestions or comments if this will be a good place to put it? Is there an advantage to putting on the plenum?
Thanks Jeff
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this looks great. but why make it so you weld it together?? why not make the 2 sides bolt together with an o-ring to seal it?? like just have half an o-ring grove on each side and then just add tabs around the outside to bolt it together. to me that would look way better and maybe even allow for different size plenum chambers to suit different taste's/preference
Good idea being able to get back inside it for testing and tuning. I looked into it but the part wall thickness would have to go way up which would add a lot of weight. Also, the plenum is really big, and I just have clearance around it for the booster, my header, wastgate and such. Welding it is simple and easy, and personally I like nice TIG welds in moderation. I guess I could always cut it back open if I had to. I also think I would have to have a wideband sensor in each exhaust runner to find variations, I am not ready for that yet.
Jeff
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So, I have pretty much finished the design for the turbo plenum. You can see in the pictures below the complete assembly. I have integrated the AIC system as well as the vacuum reservoirs into the backside of the plenum. Should make for some clean hose routing to the throttle bodies and all necessary systems MAP, FPR, gauges, BOV, AIC, EGR.
In this new version I have smoothed out the entrance into the main plenum from the entry slot where it looked to be a problem.
Turbobluestreak ran some new CFD plots of this rev. Check it out and let me know your comments.
I have the stock on order and this thing will be in the machining center next week.
Click on the pics for a bigger view
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monzter, as an engineer at such a great bike company what do you think of our bike. Any suggestions?
I think it looks great. Remember safety, not to sound like an old fart (I'm not), but it is the most important consideration in my opinion. It doesn’t matter how cool or light it is if it isn’t safe. With that in mind keep a close eye on the joints to make sure you do not have any issues with the wraps. If the frame starts feeling "soft" hang it up. With the BB installed backwards you may have to use some locktite on the BB threads and pedal threads to keep them from loosening.
Again great job, you should try some tig welded steel next time. It looks like your miters are done well.
Best Regards
Jeff
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I actually work as a Design Engineer for a bike company called Felt Bicycles. We do a few Fixed gear bike. http://feltracing.com/08/product.asp?catid=1504,1525&pid=8717
All of them come with a "peanutbutter" wrench with a bottle opener built into it. It mounts to the seat tube braze-ons with wingnuts. Good beer and bikes go together quite well.
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Hey, Whats up with the LHD? You going to run fixed or freewheel with a front brake.
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Custom frame builders actually sell this type of bike.
http://www.calfeedesign.com/bamboo.htm
Check out the prices.
Good Job, and cut that steer tube before you hurt yourself...
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From my understanding a thick cast manifold will loose heat faster than a tubular manifold. A thick manifold has much more heat soak ability than thin material, especially if the thin material is stainless. Stainless is a horrible conductor of heat, and great at handling the temps. Think of it this way, have you ever tried welding a thin tube? Low amps is all you need for good penetration right? Now try welding a thick hunk of metal, notice how much more amps you need to get the material to melt? This is because the thick heavy pc has more capacity to pull heat.
If you design a good header with room for expansion, personally I think it is all good. I built my own and it was by no means cheap easy or going to give me back in performance what I put into it, but I did it because I wanted to and I like building. If you are on a budget with limited finances then I feel the money could be spent better somewhere else. For me I had no budget and just wanted to make the coolest header I could. Here are some pics of it tacked up
Jeff
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IT IS TOO SMALL!
I made one, and it was horrid on carburettors. MUCH worse than the knockoff HKS I build in Japan.
It should be more like 4X4, which is about Cartech size, but it's still just a box and doesn't pressurize the float bowls to enrich on-boost like the HKS and SK Plenums do. With the proper entry strategy, and plenum that size could probably be baffled to work correctly, but inside an extrusion it would be a job. You may as well fabe the whole thing and not take shortcuts.
Tony I was just thinking about you comments on the old HKS manifolds. It sounds like the pressure drop in the large volume of the main plenum box isn't enough to balance out the floats. I wonder if you could tap into the system anywhere before the air goes into the large plenum and run this to the floats to get the boost like the sub plenum is providing. So a simple 4x4 box for the plenum with lines running to the float area to somewhere before the 4x4 box. Maybe before the intercooler?? Does this make any sense??
Just a guess
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Your modeling of the air flow looks neat, but at your highest velocity in the intake you are over sonic velocity, choked flow! At 6000 rpms a z flows about 8550 cubic inches per second in a perfect world, half of you model. It seam that boundry layers, the higher the velocity the thicker they are, were missed in the model. This might have been picked up and not shown in the computer model.
I still think the design is great and is a whole lot better than my 4x4 box with a hole in the end!
Not sure how the analysis was run, and if this was accounted for or not. This time I have to base the runner size on experience. Dave Rebello ported the head and was very specific about asking what engine size, cam, boost and HP goals. The end of the runners match to what he ported the head to. Actually not much bigger than stock. Interestingly the head flowed good numbers with the small ports @212cfm at 25" Dave said big ports doesn't necessarily mean good flow, but small ports help with velocity which will help with off boost performance. I guess well see
Thanks for the comments, maybe TurboBlueStreak has some comments on how the test was run.
Best Regards
Jeff
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Jeff, would you want to take a look at those old 80's Tech HKS Plenums in person? I could probably make my way your direction if you're interested in taking some dimensions. It would be interesting to see the CFD comparisons for 80's technology...
Hi Tony,
Ya I would like to look at those plenums. I could reverse engineer it in Pro-Engineer so that it could be run on CFD software, but I can't speak for TurboBlueStreak if he will run the simulation or not:icon43:. Maybe after the new year we can get together and check it out. Thanks for the offer.
Jeff
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Hey Braap,
Thanks for your comments, Unfortunately I don't know the answer, I'm just working from what just looks and feels like it would work properly. Helix posted a link above from somebody else doing the same type of design for a 4 cylinder. He had the slot facing the runners forcing the air down them. He determined this to cause turbulence in the runner and moved it to the middle like I have shown. I guess the best answer is lots of R&D to find out.
Jeff
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I think the best way to fight turbulance would be to have a completely tubular intake "header" after the TB. You could also make them equal length so you wouldn't have problems with unequal distribution...
Like this, It scares me!!!
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TurboBlueStreak was kind enough to help out with the CFD work on this new plenum Thanks. I made some changes to the model before sending it to him. Mainly, I lengthened the slot from the lower plenum to the upper plenum. The slot now goes full length. I also modeled the rest of the intake track. You can see the throttle bodies, and how they taper down to where the flange meets the head ports. I also added the throttle shafts and butterflies to see the effect. Here are some pictures of the latest design.
Here are the CFD results:
I can see from the results the radius going into the begining of the slot is too sharp, making it difficult for the air to get around the corner. I will modify it like this picture.
I am no expert at reading the CFD results, but it looks pretty consistent down each runner. I also find it interesting how the velocity increases down the runners due to the taper.
Anybody have comments
Thanks again to TurboBlueStreak
Best Regards, Jeff
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As for TWM throttle bodies, most ITB's use the standard Weber/Mikuini/Solex/OER/Dellorto inlet side carburettor flange dimensions, so it should be universal.
Tony,
Your 100% correct. The TWM spacing I used is standard mounting for all the universal manifolds out there. So really this thing could bolt up to any throttle body mounted to and triple style manifold.
I should be getting some CFD results soon; we'll se how it looks.
Jeff
:flamedevi:flamedevi:flamedevi
Calling out Jan Trondsen/Awsome S30 renderings
in Non Tech Board
Posted
Does anybody know what color that is on the sides. Looks like a Datsun factory color from a bluebird or something around that time.
I really like the paint