im building my own manifold, i want to know what is proper plenum and runner thickness for a forced induction application. the max boost i will run is 25psi, i was gonna use 1/8 tubing thickness but my velocity stacks will be 2mm thickness. will this be thick enough? i see ross machines extruded plenum material is 1/4" thick that seems a bit much and pretty heavy to be hanging on those runners

 

what kinda manifold u building? for what?

hears a start http://www.rossmachineracing.com/intakepartspage.html

 

the design has a lot to say on how thick things need to be.
a cylindrical plenum will distribute the force evenly, and can be thinner, the bigger the flat surfaces on your plenum is the more it will flex.

25 punds of pressure per square inch. if you have a flat surface that is 2x10inches that means that there is 500pounds pushing on that surface. roughly

 

i was originaly gonna just buy d-plenum material from ross, but ive been thinking about staying just round. this is gonna be for my miata project. bp 1.8l engine with 99 head. ima machinist so making the parts isnt a problem, and i have done my homework and calculated runner length for dynamic flow effect(harmonics). i have never checked any thickness's on cusom manifolds so i was sure what was considered to thin. so yeah i will be using round tube

 

bump

come on guys, i know there are people here who have built manifolds. these sheet metal box style plenums cant be made out of to thick of plate,and they hold massive boost. give me some input

 

Most of the manifolds ive seen use 1/8th 6061 aluminium sheet for the plenum boxes. Im not sure what they were using for runners though.

Ryan

 

if it's a round plenum, your weak point will be the ends. so they need to be a little thicker. 2-3 mm on the round part (1mm will probably hold the pressure, but the vibrations migth crack it over time)