Inlet Manifold Design - Triple Injectors
Turbo Mini Forums

clever stuff

Team www.sheepspeed.com Racing

std 998 A+, g295, MD266, RHF4, 109hp @0.8bar/5400rpm

Umm...

I dont think this is any good:

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."

now that IS interesting (not that the others wern't)

can you tilt the large pipe so the airflow swirls in the plenum instead?

If I put the inlet in the front or back, then it would not be as bad, but there is no space to do so.

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 you have room to get in a tapered cone and silt arrangement ala quattro.

IS that swirl not a useful thing for decent fuel mixture after the point of injection, especially given the limited window you do have to get the fuel in?

I tend to agree - it depends where the injectors actually are in the parallel bit but if the model is correct, it shows the velocity down the runner becomes uniform about half way down.

Once the velociy is uniform across the runner, I don't see why it matters if it's still swirling unless the injection window is so small it catches only one half of a swirl rather than multiple swirls....

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

My immediate reaction is to avoid swirl, buts that's from years of dealing in water flow where swirl is of no benefit unless you are mixing.

The fact that the velocity profile has evened out by the outlet is definately a positive. On the negative side, the swirl means higher velocities against the pipe surface which will incur a greater pressure loss.

One thing that I do know is that the 998T manifold with the central inlet seems to work vey well. It may be a good idea to model that and see what is actually going on.

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."

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."

Does it do the same thing in the other inlet?

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."

This is an interim development of the 998T manifold:



Obviously putting the inlet and outlet in the same plane prevents the swirl in the outlet.

I'll now develop the outlet to replicate the 998T manifold with the double bends, but I expect it to show nice straight flow at the outlet.

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."

This is the 998T manifold (currently in use and performing well).



Not much swirl at the outlet.

Right I'm inclined to just add a 100mm long taper to the end of the plenum as shown here:



That seems to give the best result.

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."

Have you tried modelling the effect of a taper on the runner tube instead, ie, starting larger in the plenum and tapering down towards the port ???

(so the initial "swirl" is at lower velocity so less surface drag)

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."

Have you seen the Audi manifolds ?

There could be some clever engineering going on there. Cossie one is along similar lines

http://www.bufkinengineering.com/intake%20manifolds.htm

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

i like this ..

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

Oh man, that's quality!

interesting site too, just spotted this, audi only injects on 1 of the 3 intake valves.

very indeed !!!

I guess higher velocities make for better spray ? using a single port like that ?

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

Great thread ! Love this brain storming different idea stuff.

Really gets my juices flowing.
Cheers !

"So wat we gonna do tonight Brain?"
"Same thing we do evernight Pinky!"
"Try to take over the world!"

That Audi design may well work well on a flow bench with all 4/5 ports flowing continuously.

But, I can't see the advantage when you consider that the flow in the inlet is a series of slugs feeding individual cylinders. The tapered section just does not make sense.

The flow at the inlet of a manifold is not the combined flow to all the cylinders, it is a succession of equal sized slugs that go to different places. So why have the tapered section? The slug feeding the furthest cylinder would have to accelerate to get to the end of the taper.

It's like parallel or serial data transmission. Inlet manifold flow is serial.

Edited by Paul S on 14th Jun, 2010.

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 insteresting stuff, much of which is pure jibberish to me! Theres clearly much more to it that simply pumping air into a carb!

Think one of these will fit in the back of a mini?

Fire Up The Quattro ya nonce!

1/4 Mile 14.3secs 96Mph Terminal 10psi of boost.


Fibreglass Parts? - http://www.tdkracing.co.uk/
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Although a series of pulses, they will overlap to some extent depending on the cam.

But more to the point, the total mass flow is five time larger at the inlet than the far end, and will be behaving a lot more like a continuous flow than a series of pulses. Only towards the far end will the pulse(s) become more defined.

If it was absolute pulses (like you serial data analogy) all the way down I would agree the size/shape doesn't matter but with a very different flow regime at the inlet compared to the far end, there probably are benefits to a slight taper - after all, it isn't a 5:1 taper by any means, more like a 5:4 from the picture.

Or, to put it another way, the serial data analogy would be OK for a non-compressible fluid but not for a compressible one.

EDIT - typos

Edited by Rod S on 14th Jun, 2010.

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."