Sequencial injection idea...
Turbo Mini Forums

Hi,
If we mounted 4 indentical injectors 2 next to each other per port, would we then be able to use each injector to feed 1 cylinder?
If so, with a sequencial firing ECU we could swap the 1,3,4,2 firing order to 1,1,2,2,1,1 by simply swapping the injector wiring around.
I realise there's still the timing issue to sort, but would this idea sort the firing order problem?
If using MPi injectors for example, what sort of boost level would this support?
If it's a crap idea I'm sure someone will say so! :$
Cheers,
Gavin :)

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That's a good idea.

As long as the injector firing coincides with the valve opening.

I think the problem may be that to ensure that the fuel from an injector goes to its associated cylinder, it can only be open for a maximum of 25% of the time. Usually this is about 80%.

Even if you use 4 large injectors, say the Rover MPi ones at 460 cc/min, then you have only got enough for 90hp ish.

The MS Siamesed Code plan is to fire two injectors at the same time into the same port throughout the period that the inlet valves are opening. The injectors can be open for about 45% of the cycle. Then 160hp may be possible with the MPi injectors.

If you want more than that then you need larger injectors but you run into problems with the resolution at idle. So there should be the facility to run large and small injectors and stage them.

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."

Not being funny but if this is such a good idea, why did Rover not do it? and spend shed loads of money on developing sequential timed injection.

I think theres more to it than just fitting another two injectors, and all of which im not to clear on myself

Hi,
It will still have to be sequential timed injection even with the 4 injectors. I just figured it would make things easier, might be a bit tight trying to squeeze 2 injector into the manifold runner!
Thinking about it some more, I seem to remember one of the problems was the time taken to open and close and open the injector to get the 2 injection events in the one port. This idea would surely free up some of that time?
Sprocket .. I would imagine to keep the costs down of the extra injectors and ECU components. Rover wouldn't be looking for the power we're after as the g/box wouldn't like it...... They would be looking for cheapest way to get emissions compliance.
Cheers,
Gavin :)

Edited by Bat on 11th Nov, 2006.

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What cam do You recommend with turbo and sequencial injection?

cheers
TCC

Hi,
Welcome aboard!
According to theory, yet to be tested, a scatter cam would be best with injection.
With a turbo fitted you'll need a cam with a short over lap, and long exhaust duration.
What injection system are you thinking of using?
Cheers,
Gavin :)

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4 injectors is a good idea. The problem is that most affordable aftermarket ECUs don't have 4 injector drivers. The Emerald M3D sequencial does and some of the MOTECs (not checked the latest OMEX).

MS3 (which is due this year) will have enough drivers to do this, so if someone has time to adapt Jeans code for this then you can have all the options you want.

Bat, what you suggest may be possible to impliment but not with MS2 for the reason Bill states. Staged injectors however can get over the duty cycle problem as you could keep the normal injectors to work with idle and then have others for the extra fuel when required.
This is how I am planning on doing the instalation.

4 injectors, 2 pairs side by side, could well give some major packaging issues too. Staged injectors would have the normal pair in front (nearer head) and the second pair behind (nearer butterfly)

With these pairs of injectors the max individual duty cycle (injection window) would remain the same but the extra flow would allow for more bananas.

Every day is a school day ...........

How fast and how expensive ...... the same question...

As far as cams are concerned it'll be teh same cam as you'd normally use with a carb as quite simply there isn't much else avaialble ... that may change though if injected turbo becomes the norm.

Every day is a school day ...........

How fast and how expensive ...... the same question...

Hello!

My plan is use 4 injectors, 2 big and 2 huge ones. Idle to around 2500 rpm big ones and after that big and huge ones together. I try inject when only one intake valve is open, not when they share port. That is the reason I need those huge ones (cycle is max 25%).

cheers
TCC

Tcc - Size of injectors doesn't account for everything - a 900cc injector that takes 1.6ms to open for example, along with erratic control is pretty naff.

In theory, two (four) Mpi injectors will fuel an awful lot of horsepower...

Dave, as you say if the opening time is very large trying to inject only on an open valve (full sequential) becomes very difficult. However, with the semi-sequential once per rev injection then the opening time is meaningless because you have plenty of time between pulses.

And I don't have anything to add to what Axel and Roger said.

However, I'm planning to have the MS2 be able to control separately 4 injectors. This will require a small modification to the MS2 daughter board, some additional components for the injector drivers, and, of course, some code modifications but it will allow fully sequential injection.

This will also allow, and this is more interesting than full sequential in my opinion, to do individual cylinder trimming of the amount of fuel for a cylinder and injection timing. The tuning effort for such a setup will likely be quite high but would allow to extract every last bit of power out of an engine.

Anyway, there is much work left to do before we get to this, so if anyone is ready for bench testing, let me know.

Jean

http://www.jbperf.com/

Jean ...... don't tempt me away from my initial plan ... that will be a big enough challenge to get running well .... fully trimmed, fully sequential to come later ...... Now how will we fit them all in?!?!?!?!

Every day is a school day ...........

How fast and how expensive ...... the same question...

Dave, as You know about 160 kW needs about 1350 lbs/min injector at 25 duty. So it has to be big.

cheers
TCC

How did you work that out? I only get 480lb/min

215BHP is quite a few bananas but I'm sure you don't need 1350lbs/min to achieve it, even with just two injectors

Every day is a school day ...........

How fast and how expensive ...... the same question...

First of all, you're mixing 2 different units for injector flow rating. It's either lbs/hr or cc/min. With 1350 lbs/min, you'd need a tanker connected to your car to cover any reasonable distance :)

Second point is that with the correct sequential code, you're not limited to 25% duty cycle but you can go to 45-50%.

So for 215bhp (huge power by the way), you need about 100-120 lbs/hour for each port depending on your BSFC. This is doable with a single injector per port but you wouldn't want to do it that way if you want to be able to idle at something below 3000 RPM. This is the reason why staging is necessary for high power engines if they're to be used in any normal fashion.

Cheers,
Jean

http://www.jbperf.com/

Hi! Yes, my mistake (where the hell I get those lbs)? I mean 1350cc/min ofcourse. Is it only true that I cant inject only when one intake is open? This means duty cycle 25?´And 215 hp is big power!

Cheers
TCC

duty is measured over 360 crank degrees, hence a valve is open a little over 180-(crank) degrees, so it's around the 50%, not 25%.

Hello!
Are You sure? I though they measured it on cam degrees.

cheers
TCC