CNC Billet Injector Bosses and Manifold
Turbo Mini Forums

Too yellow, they should be much greener.

Try keeping them in the fridge.

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

Nah, it's all to do with the L/D ratio :)

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

My bananas have finally arrived from the US. Nothing special, but I could not find them in the UK, well not in small batches anyway:



About £20 each, half of which is the postage and import duty etc.

I call them bananas not just because they are banana shape, but by extending the intake runner length, they create more torque in the 4k to 7k rpm range than any other modification. Combined with a short intake duration, high LSA cam, charge robbing is minimised.

Next job is to try to CNC mill them to shape. Also going to try to CNC the complex hole in the plenum

Edited by Paul S on 29th Nov, 2012.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

What do you call a collection of plenums?



Crude but effective jigging going on today :)

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

That seems very thin walled.....

Welding or your new glue ???

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

It's actually 2mm thick, plenty :)

Going to try my new "glue".

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

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

For those interested in the CNC process, we start with a solidworks 3d drawing of the part:


In this case it was a simple revolve to create the tube and then a revolved cut to create the holes. Solidworks is great for this because it works like you would make things. Start with the material and then lops bits off. You have to put paper or AutoCAD concepts out of your head though.

I then ask Sturgeo to make the G-code from the drawing and him being a good lad, he does as he is told :) Actually, I need to work out quite how he does it with SolidCAM, but I think it basically involves selecting an origin which will be the X,Y & Z zero for the tool, selecting a profile to cut and selecting the end mill. You can do a 3d simulation of the tool path as a double check.

We then take the G-code to the computer on the machine, load it up, check to see if the tool path shown in Mach 3 is OK, zero the tool to the workpiece and off we go.

I've just drawn this:


Took about 15 minutes. Tomorrow, we should have time to create the G-code and cut the 6 runners.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

I dont think i will ever understand cad lol

That is exactly what I did with my first efi manifold too. I used the bananas from the escort 1.9 that Marcel Chicak used on his EFI manifold. I was never convinced by the flow going into the bananas with that shape - never did any analysis, it was just "seat of the pants" feelings that it didn't feel right.

To make myself feel better, I ended up sawing my plenum in half too becuase I wanted to weld it on the inside and then smooth it so that it'd have a better flow into the bananas.

And of course once I cut it, it distorted all to shit because it was all welded on one half of the tube and not on the other half that I cut away...

I still have what's left of it in my box of bananas - I cut up six manifolds in total.

Well, the full transient CFD analysis did not show up any real issues.

https://www.youtube.com/watch?v=Wf4u7L2Qt60

It must have been a problem with your pants Dave :)

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Actually, I know that the current design is compromised due to the packaging constraints. The ideal configuration would be as the original Mig manifold:


However, in a conventional mini that puts the throttle body either where the clutch master or the wiper motor sits :)

So, out of interest I thought that I would attempt to evaluate the difference. Firstly a plot of the velocity trajectories in the new manifold:


A cut plot of the velocity in the plenum and runner:


And a cut plot of the pressure in the plenum and runner:


So now if I compare that with the Mig manifold pressure plot, I can evaluate the difference:


I reckon that it's about 0.03 Bar or about 0.5 psi.

There is deifinately scope for improvement, so I shall be cutting a decent radius of the "short side" to get rid of that knife edge that seems to be creating a problem.

EDIT: the plots are all at maximum port velocity on a 1293 at 100% VE peak, so at the extreme.

Edited by Paul S on 3rd Dec, 2012.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

my head now hurts

Back to practicalities this afternoon, cutting bananas:

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Very nice Paul.

1275 N/A Sprite, 998 T2 Turbo Mayfair
1275 EFi Turbo

really interesting .

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM