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Posted

the old site had a thread on plenums and designs.....perhaps a new thread could be beneficial for upcoming projects !  there are so many designs being used out there but how many are actually efficient ?  pros / cons / do's and don'ts .   

Posted

here's one i made years ago on my katana that I shouldn't of sold so I'm building another lol 

the other one I didn't make but will probably modify it & set it in a bit closer to the engine as the turbo is just poked inside at the moment 

 

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Posted

Here is something that I made few years back.

Inside:

plenum1.jpg

And finished part.

plenum2.jpg

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I don't know how efficient it really is but based on EGT readings flow balance between the cylinders is pretty good. And engine produces quite healthy power figures compared to boost and tune of the base engine so the plenum can't restrict flow too badly either.

In my opinion the most important target for plenum design is to ensure even air distribution between the cylinders. This can be tricky if air is entering from side. Velocity of incoming air tends to pack air in opposite end of the chamber and then cylinders on that side will get more air. To prevent this some kind diverter arrangement is needed. Typically this is done with dual chamber construction like on my plenum and those in second post. Idea is to kill air velocity in the first chamber and then bleed air to the main chamber through narrow slot, row of holes or something similar. 

  • Like 3
Posted

Borrowed Arttu's design a few years a go for my slabby used the same plenum with a bit of alterations on my bakker.

Works for me never measured egt on cilinders so cant say if all cilinders get even airflow

I scratched my head about plenum design when i made this plenum cause i wanted to make the best plenum available but i must say my first simple plenum made of 60 mm tubing worked perfect also ...

 

 

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Posted

Ok..... as I need to get my plenum sorted  and am in the process of getting a design configuration.... I noticed several types using some sort of flow control . As this style is my first attempt and I am not sure of the hole sizes ..... I just don't want to create too much back pressure . Here is what I am starting with ( test piece #1). Oblong hole with radius .... 19 mm x 6 mm ..... quantity of holes not yet determined .  I wonder if radiused round holes would be better ?

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Posted
14 hours ago, no class said:

Ok..... as I need to get my plenum sorted  and am in the process of getting a design configuration.... I noticed several types using some sort of flow control . As this style is my first attempt and I am not sure of the hole sizes ..... I just don't want to create too much back pressure . Here is what I am starting with ( test piece #1). Oblong hole with radius .... 19 mm x 6 mm ..... quantity of holes not yet determined .  I wonder if radiused round holes would be better ?

Rule of a thumb is to make combined cross section of the holes the same as plenum feed pipe. Radius won't hurt I guess but on the other hand probably won't make big difference either. In the end the idea is to create restriction to direct air flow. So better the holes flow less effect they have. To some degree. Of course it would be better if you can change air flow direction smoothly without creating too much back pressure but usually this requires more room. It's balancing as usual.

  • 1 year later...
Posted
On ‎4‎/‎28‎/‎2017 at 6:05 AM, Bigkenxx said:

IMG_5537.thumb.JPG.c4c59d3742b518ec580fff4e496c87c8.JPGsimple but it does the job 

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I am about to build my first Plenum.

What are the thoughts about a simple design like BigKen but have a plate above the inlet forming a lower chamber and a row of slots in the plate.

Would that cause too much backpressure ?

Posted

I know mine is simple to others but I can only report how mine is I’ve had no problems runs great , boosts well but I’m not going all out but I can only admire  the engineering in others quest for boost 

Posted (edited)

To be honest I was just going to copy what you have BigKen.

 But after looking at the way other people have made them with different methods of getting balanced  air delivery to each inlet I thought it would be easy to make the plenum a little deeper and add a plate to form two chambers.

I havent a clue if it would make anything better but I am worried about making things worse lol

Edited by mick-ne
Spelling without glasses !

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