Inlet Manifold Design - Triple Injectors
Turbo Mini Forums

First stab at a design for the 200+hp 1293cc engine for the Miglia.

Following the latest test of the siamese code showing that I need around 2500cc/min per port to achieve 250hp, then I've decided to try to fit 3 * 800cc/min injectors.

Initialy I thought I would need to fit two on top and one below. However, I think I can get all three on top by arranging the injectors as follows:


Machine the flange and pockets from a single block of alluminium to minimise the welding as so:


This is the critical path to getting the Miglia running.

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."

with mutiple injectors that close to each other could the sprays interacting become an issue?

Just waiting for the glue to set on my "Blue Peter" mockup - my CAD skills (or lack of) are being used on PCBs at the moment....

I don't think interaction is an issue if the centre one is stage 1 and the outer ones both stage 2.

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

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 thinking about it the cone would have to be pretty wide for them to converge.

Have you thought about the fuel rails? For the bottom two injectors its easy, but the top four could be tricky as there not straight is that makes sense. Just something to consider before you start fabrication.

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."

Right,

Couldn't wait for my glue to set so in true Blue Peter style, wood, cardboard and Fairy Liquid bottles....

Single as already proved for me.



Double as under construction but not finished.


And triple without all the glue being set.....


What is really interesting, the angle of the outer injectors actually brings them closer to the manifold so I don't have such a big worry about how far back the plenum has to go.

The fuel rail WILL be a nightmare, but that was true with my two per port design.

As you say Rob, nothing is impossible if you are an engineer, and I like a challenge.....

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

Rod, I think you idea is best for spray etc.

But, how would you make the fuel rail? I think you would need to make individual "rails" for each injector and connect with flexibles.

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."

The fuel rail will be interesting...

On the single injector per port design I just threaded the tube straight and screwed it in with (my favourite) loctite.

For multiple angles, getting the tapered threads to "bite" at the right point will be "difficult" to say the least.

So, I guess, single stubs and flexibles inbetween, BUT, with trying to get a decent angle on the stubs so the flexibles are actually "straight".

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

Machine up a top hat to go over the injector, with a barbed fitting on it. Or else one of the typical AN threads.

That will leave the fuel supply pretty easy, just requiring a seperate flexible fuel line each.

Build a small remote manifold or fuel rail with multiple outlets to supply them all.

Im sure securing the rail and top hat into the manifold shouldnt be that difficult with that setup. Perhaps a small flange and some threaded rod. beside it.


Then you have a flexible system to mount injectors anywhere or any shape you want.

Was it old Cavaliers that had injectors with a barbed fitting on top ?

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

Edited by Rod S on 9th Aug, 2009.

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

something like this steve , ,

i think id run one close to the port then the others on top of the plenumbillium

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

Robert,

Really nice in your configuration, but...

look at mine side on with just two injectors



No room for flexibles on the middle one if there were three per runner.

I think I can do it with flexibles to the outer ones, but complex.....

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

Wouldn't that work with a barbed fitting on the front and the fuel rail (or distribution block) just by the rocker cover?

Jean

http://www.jbperf.com/

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

Bit of an update.

Changed it a bit to make it machineable.



Decided to put the two injectors at the bottom so that I could keep the port round at the face.

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."

Do these injectors require the same bore size at the manifold and in the fuel rail? If not, do you have enough clearance between the injectors in the fuel rail? Any idea how you're going to connect the fuel rails: in parallel or in series?

That single injector is really going to splash it's fuel on the floor of the port. I'm not sure if it's a good thing or a bad one or if it just doesn't matter.

Jean

http://www.jbperf.com/

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."

So my change,



The right one isn't down in position because the flange hasn't yet been machined for the slots, but you can get the idea....

There are lots of possibiities here.

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

It may just be from the angle of the picture but it looks like you're going to have fun tightening the nuts on the manifold with the injector pockets in the way.

Jean

http://www.jbperf.com/

Rod,

Just make sure that the two innermost injectors are not going to fight for space.

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."

They are in the photo, in practice, they will clear..... Just.

The angle of the three bosses isn't quite what it seams from the photos.

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

you guys really are determined...

Would the Bosch 1600cc injectors be of any use ? once beyond the limits of say a single 650cc or thereabouts ?

3 inj per port really does seem messy...there has to be a better way.

And is it essential the injectors are mounted close to the valve ?

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

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