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Inlet manifold feedback...
J666AYP - 26/4/18 at 08:57 PM

Gents,

Just having a brainstorming session in the garage. Could this work? (excuse the lack of primarys its just a mock up and dont want to waste my time welding it if its no good)

Jay



snapper - 26/4/18 at 09:12 PM

There should be some sort of inlet trumpet in the box and the very narrow profile of the box at the far end is very restrictive.
You need more room between individual inlet hole and the face of the box.
There is a volume of air in the plenum that the negative pressure created by the piston descending draws on, because the induction is not linear you don’t want the volume trying to move back and forwards up and down the plenum.

A bit difficult to describe but I hope you get the idea.
Basically the very narrow far end is not a good desighn

J666AYP - 26/4/18 at 09:37 PM

Snapper,

I thought narrowing the back would speed up the airflow towards the rear end and ensure that the last cylinder would not be starved of air after the other 3 have drawn air in?

I may have that completley wrong (the logic seemed so strong lol).

Back to the drawing board it is

Cheers,

Jay

bi22le - 26/4/18 at 09:56 PM

I am lucky enough to have access to CFD software and I can 3D CAD model quickly. Snapper is bang on. The first three will take all of the air. Remember the engine is still sucking the air, even though it's under pressure.

I tried designing various home brew versions and then realised that actually the best designs are already out there.

Google to death after market turbo plenums for any make of car. If you can hit on Motorsport ones that's even better as they are normally completely uncompromising.

theduck - 26/4/18 at 10:10 PM

quote:
Originally posted by J666AYP
Snapper,

I thought narrowing the back would speed up the airflow towards the rear end and ensure that the last cylinder would not be starved of air after the other 3 have drawn air in?

I may have that completley wrong (the logic seemed so strong lol).

Back to the drawing board it is

Cheers,

Jay


That theory is correct, but I think the point is it narrows too much

J666AYP - 26/4/18 at 10:40 PM

Oh well, win some lose some.

Cheers gents I will get back to the drawing board.

Jay

coyoteboy - 27/4/18 at 02:49 PM

quote:
Originally posted by bi22le
Remember the engine is still sucking the air, even though it's under pressure.


Technically, the plenum air is pushing in on the lower pressure area generated by the opening of the valve on a lower pressure cyl, sucking is a misnomer here - forced induction or natural, the process is the same, only the absolute pressure values change.