Plenum chamber

[superls]

Anyone konw anything about there design or what criteria they have to meed when building one?

cheers in advance, superls

 

[badj]

It is just a 'chamber' where the air pressure is stored, or regulated. The idea is that is supplies a constant pressure for an irregular demand, so that the delivery is a bit more even.

Some manufacturers use them on inlet piping purely because the pressure also works as a sound deadening - reducing inlet noise. (Y)

The pressure has to be at a positive amount in comparision to atmospheric pressure, its the same principle thats applied to hydraulic systems.

 

[Noddie]

mph has been designing one for the k11, might be worth asking him...

 

[frank]

Anyone konw anything about there design or what criteria they have to meed when building one?

cheers in advance, superls

the 1.4 plenum and runners hold just over 1 liter scott, and the 1.0 is the same size (so the volume/design can,t be that critical eh)

 

[Alienfish360]

The difference been that the Micra wasn't designed for performance, they just used as many identical parts to keep costs down.

There is a few very good articles around with relation to Inlet Manifold design, but it's admittedly well over my head, and the maths is very involved.

 

[superls]

basically as i see it, the csa (cross sectional area) of the plenum has to be a multiple of the number of ports its providing with air? let me explain a little.

the very end of the plenum is only feeding 1 port so its csa has to be the same and 1 port as a minimum, the inlet of the plenum is supplying all 4 ports so its csa has to be equivalent to the csa of 4 ports as a minimum.

would anyone agree (or disagree) that this makes sense?

ive made an excel spreadsheet to calculate the radius of the plenum at the intervals of the 4 ports, it also calculates the volume of the plenum chamber, the shape of the chamber im designing is like this

obviously the ports attach to the flat edge.

but id say at a bare minimum the volume of the plenum chamber has to be the capacity of the engine?

thoughts anyone?

 

[frank]

each port/runner is only drawing a short slug/pulse (one at a time) tho eh scott ?
at a rate of 2 per rev ?
and modern engines tend to have very long thin runners (like a bunch of banana,s )

 

[superls]

just knocked these up to show what im thinking its going to look like.

 

[frank]

well, a similar design was used on the 200hp sr16ve eh scott, so yeh (Y)
http://www.micra.org.uk/attachment.php?attachmentid=13563&stc=1&d=1253395728

 

[superls]

excellent, something else on the fabrication to do list for when the new workshops built.