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Turbo Intake Plenum


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Is it Ok to link some of your pictures to that thread?

Could you tell me the height between the floor and roof in your main plenum?

Did the size (volume) of the main plenum stay the same as when you started this project?


Hey Porsche Guy,

Ya, no problem, use the pictures, I have no problem with it.


Distance is around 72mm

Volume stayed the same per my original plan


Good luck with your project





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Monzter - good work, man. I love seeing your craftsmanship.


I own 2 books on manifold design and I was wondering if you know for sure if intake pulse reversion matters for boosted applications? I'm having trouble thinking through the dynamics in a boosted application. It doesn't look like the runner inlet to the manifold is ideal based on what the books say - but everything I've read is for N/A applications.


How did you set up the CFD... Is it forced in from the inlet and you let the 6 runners determine flow rates or do you assume equal flow rates at the runners and suck the air into the manifold?


Do you expect the dynamic nature of air in a manifold to have a big impact on flow in the manifold? When the valve is closed there will be a wall of air blocking flow to that port creating inconsistencies. Sorry for the rambling.

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Look to industrial compressor TWebb, the plenum sizing is very similar to that used when sizing a receiver for a reciprocating booster compressor off a centrifugal or screw compressor running on a capacity control system with only 30% capacity turndown.


No throttle plates, but the dynamic compressor feeding a positive displacement reciprocating compressor is the same thing.


This goes only towards volume considerations, flow in each runner is likely a science I'm not even going to get into!

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Wow, I just read this whole thread. If I go FI, I'll definitely consider something like this. Though mine would be much more crude. I know this is built already, but I just found the thread.


I'm anxious to see it all hooked up and running, I mean You've shown us the proto and the new head now, but so far as it compares to stock numbers would be very interesting to hear.


Some thoughts on the design. The "slot" the air enters from the intake could be used to control pressure by varying the width from the fron to the back, though the problem is sorted by your internal fins. Another thought was that these fins could be shaped into "wing" airfoil shapes to vary your airflow for fine tuning. lastly one furthor suggestion would have been to include some sideways "C" shaped portrubances above the intake ports in the upper plenum to direct flow down the intake throats.


How are you planning the intake from the output on the Turbo (which Turbo were you planning on using too?) It looks like your turbo is mounted low which could induce turbulance into the plenum itself.


I liked the idea of blowing up a junkyard L28ET with it, but that's fun w/o a fancy plenum.



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  • 2 months later...
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Rolling a cone is a basic sheetmetal fabrication skill. Look to any HVAC Duct Construction layout book, and it should show you the layout for a cone. Stick it in the slip roller and you're done. Easy Peasy!


Basically, you lay out two arcs which scribe through the circumfrence of the circles at the repsective ends, and cut a pie-wedge shape out of sheetmetal with the respective arcs at each end. It's a horrible explanaiton, but when you see it laid out from the text in the HVAC Duct Book, you will see what I mean.


Start on page 2-19 on this link, and it will make more sense. "Frustrum", "Trammel Points", "Bisect".... ahhhh, old trades class, what has it been now, 25 years?



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I'm on my 2nd read of this thread and I'd like to ask where one can find the same excel spreadsheet that was used for Turbo matching. It seems like the most straight forward application for identifying the flow pressures and pressure drops.


Amazing thread. I've been a member for a so long and I can't believe I never read up on this until now.\




I'm really sorry to bump such an old thread.

I'd also like to inquire as to how many hours was utilized to manufacture the piece.


That way I can get a sense of the pricing for myself.



- Billy

Edited by drunkmunky
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I still stop in on the Z forum from time to time, Been busy with Family and other projects, so the Z is getting not much love. I finally got the engine back from the machine shop. All the money I saved to complete it was sitting around so long that i decided to be a good dad and take my family on a surprise vacation to Hawaii. It was a wise choice, as my daughter is getting older and wont want to spend as much time with me once she is a teen, however the Z will still be there waiting to be finished.


I got rear ended in my truck a few weeks back, so been driving my other Z every day while the truck is in the shop. I missed it.


So to answer your question about machine time, I remember about 8 hours with set-up for machine run time. The roughing goes quick, then the finish step-over passes were not super fine since I was going to clean it up by hand.


Regards, Monzter


BTW, I know its been a long time since the switchover, but I still just don't like this new format to the forum, I think I am getting too old and resist change.

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"All the money I saved to complete it was sitting around so long that i decided to be a good dad and take my family on a surprise vacation to Hawaii. It was a wise choice, as my daughter is getting older and wont want to spend as much time with me once she is a teen, however the Z will still be there waiting to be finished."


Curiously I made a similar decision some time ago---I can tell you, the Z's will wait. The trip will remain much longer in their minds than you would ever think possible.


Funny thing...I was talking to a Japanese guy about this project while there earlier last month and I discussed where you 'work' and just then we turned the corner and there was a shop in the suburbs of Tokyo with a shingle hung: "Trek & Felt" :blink: It was funny to be discussing it, say something like "Unless you're really into top-end stuff you probably won't recognize it" then literally turn the corner to see a distributor where you least expected to see it!


Okamura said "Them?"


Yeah..."Them!" :P

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Hey Monzter


not to be a suck up or nething but thanks for sharing all the information. I don't own a Z even though I've been on the forum for ages but the information you posted has been very education and informative. It will allow me to build my own intake manifold and gives me some sense/idea as to how the flow dynamics work. Just brilliant.




- Drunkmunky

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