Plenum design
Turbo Mini Forums

I am looking at making a plenum for the 7 port, i am not going to worry to much about volume as it will just fit in the space i have available regardless if its optimal or not.

Any thoughts on shape? has anyone built a simple plenum of equal shape from end to end and had good results? or should it taper down at the opposite end to the throttle body?

Are trumpets required? looking online it seems some of the high end bespoke plenums do and some dont, i assume a nice radiused edge is a good start.

For my K build I originally had a Semi circular log type plenum with the throttle body at one end, I sent the Car to Clare and Bob at Concept racing for an intercooler to be fabricated and the feedback from Bob was the design was poor and advised that the shape should be tapered to promote flow to the furthest cylinders from the throttle body.
I think volume ended up a tad over 1.3x engine volume.

First image is the abortion I made for my K100 build as described above, the other pictures are for the revised plenum for my 16v build with radii on the inlet runners and tapered for improved flow.
Im not sure how the space constraints compare between 16v BMW heads and 7 ports but my engine bay is a tad snug.

Is there any reason your opting for a plenum over ITB's or is it solely space driven?

Shane.

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Edited by shane on 1st May, 2022.

If it's a boosted plenum, I wouldn't worry too much.

Carbs or EFI ?

Any rough plans as to what you propose ?

Blowing into one end ? middle ? top/bottom ? etc What space have you for either ?

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

EFI

I think it will be blowing in from one end, no space on top and next to no space underneath. Single throttle body.

Mine is single TB and in from one end.

It's tall and slim and I fabricated an internal splitter so the TB was split 50:50 between each end.

I did post a lot of photos on here how I did it but when Photobucket commited comercial suicide they all didappeared.

Schrödinger's cat - so which one am I ???

when I built mine I used a flat alloy plate with the 4 holes in for the trumpets to hold the plenum chamber onto the throttle bodies then I welded the sides on with the blown air on one side and the blow off valve on the other side then bolted the back plate onto the box with a gasket