Inlet Manifold Design analysed....Warning BIG Post. Not 56k Friendly!

Afternoon...

Whilst this is actully distracting me from designing an inlet for a race engine, Id thought Id show you anyway.

This is an inlet manifold Ive been designing to fit a 1242cc 8v SPi Engine, it'll also fit the 1108cc SPi and with mods would fit the 8v MPi too

It looks a bit like this

Ive been running it through an analysis package to see what the flow is like...I can't do a dynamic engine cycle in this / I cba figuring it out as Ive got bigger fish to fry atm...so Ive done a series of static analyses on it taht approximate an 1-3-4-2 cycle.

On cylinder 1 inhalation:


On Cyl 1 and 3 overlap period:

Cylinder 3 Inhaling after Overlap Period:

Cylinders 3 and 4 during Overlap:

Cylinder 4 inhaling after overlap:

Cylinder 4 and 2 during Overlap:

Cylinder 2 inhaling after overlap:


As you can see, theres quite a lot of turbulence caused / pressure losses around the point the runners meet the main chamber. This is as the joint is 90-degree. it needs to be radiused ideally...Im gonna give that a go eventually.

But overall average pressure loss is around 0.003Bar...and theres some swirl in the runners (notice the flow is reasonably straight), but not too much (its not all over the place- like at the chamber-runner joint. So it should perform reasonably well...

1 and 4 look like they will starve, it looks abit like the alfa v6 inlet except for the throttle position not being on the side.

the idea of having equal length pipes is great however do your flow test again with diagonal plates stopping the flat wall in your design on each side I think it would work much better (like a triangle instead of a circular striaght - christ whats the shape called).

I would post pictures of my meaning but I do not know how to do this.

Please pm me your email address and I will show you what I mean.

Thanks,

Like baffle plates in an exhaust?

That'd definately cause problems IMO...thats bound to cause petrol-pooling...

According to your simulation what shap diameters and lengths and plenum volume did you come up with?