Siamese Code Trial - Take Four
Turbo Mini Forums

Started a new thread as the last one has become a bit lengthy.

Today we've been fine tuning the settings from the last trails, so that we have a great setup in NA mode with minimal stumbling and close AFRs up to 5000rpm+.

For any NA engine this has to be the best fueling system available. Better than any carb by far.

As an experiment, we then doubled up the injectors, 2 per port, both firing together using the single pulse mode. The injector capacity on each port is the 375cc plus the original 480cc injectors, giving a total of 855cc/min.

We reduced the Req_Fuel accordingly and it started straight up and idled fine. It just needed a slight adjustment to the injection timing at idle to get the AFRs equal.

Under load it was a different matter. We spent about half an hour on the test track trying different settings. This time we were getting too much fuel in the outer cylinders. We kept advancing the injection timing by 10 degrees a time, the all of a sudden we were at the sweet spot at 6000rpm. Both inners and outers running at 12:1 AFR.

Oddly, in this configuration, it needs 90 degrees more advance at the top end.

So a couple of positives: firstly it will idle fine with excessive injection capacity. Pulse widths were around 1.5mS at idle. Secondly, there seems to be plenty capacity to maintain equal AFRs under boost.

A lot more tuning needs to be done to get equal AFRs across the range, but not a bad result for an afternoon.

Feeling a little more positive 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."

Excellent work Paul, great progress made!

Well done, better tha ordering a VEMS or starting on the bike head....

Now the interesting bits,
First, really good to hear it idled OK with such a large (combined) injector capacity - I was hoping to prove that myself but I'm still well behind.

Second, the fact you initially had too much fuel for the outers, when you have struggled to get enough previously..... This must point to the new (combined) injector characteristics and I can't help but keep thinking it's down to runner design and injector location - ie, wall wetting and transit time. Those parameters were refered to by Leyland/Rover at the MPI design. Was your "second" injector that you brought into play, the one nearer or further away than your initial trials ???

This is where our testing is going to drift apart wildly (once I start for real).

Have you considered adapting your Miglia manifold design (with the twin widebands) to fit on the 998 for turbo testing or is there just too little space ???

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

Yes, the additional injector is the furthest away, but only by an inch or so.

But, more importantly, it is the MPi jobbie with the cone spay nozzle, so it is likley to be sending fuel to the walls.

I should really have four identical injectors, but the MPi ones were still on the car blocking up the holes in the manifold and fuel rail whilst I was running it with just the two injectors.

I do know from the previous trials that the MPi injectors need more advance.

Funnily enough, I was thinking earlier how I am going to properly monitor the AFRs under boost. Watch this space.

Anyways, I just spent another 10 minutes on the injection timing. Plugged in 135 degrees across the top three lines of the timing map. The AFRs are within 1 of each other across the board.

Mutts Nuts indeed.

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."

Captain Slog:

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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."

Impressive AFR match - you must obviously be feeling better now.

But you'd better get your gear changes a bit quicker if you're thinking of taking it on a timed run anywhere

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

On 16th May, 2009 Rod S said:
But you'd better get your gear changes a bit quicker if you're thinking of taking it on a timed run anywhere

Edited by Paul S on 16th May, 2009.

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 have been wondering about measuring AFR pre-turbo (I assume that is what you are interested in)
I have found this
http://wbo2.com/lsu/Y258K01005e03mar21eng.pdf
which at the end of the document shows the change in pump current with pressure.
With this I guess you could post-process your data to calculate true AFR , or if your so inclined write some code to adjust the values from your lambda controllers for closed loop control.

Good to see you making significant progress (again). And the AFR match is good indeed.

It would be interesting to see what timing would be required if you switched the injectors around. I can see that you'd need more advance with an injector further away but 90 degrees is a lot. As you say it's probably due to the spray pattern. Might be that it would help speed up the fuel if an injector with a pencil spray pattern is further upstream.

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."

Won't that still be at the same pressure as the manifold though?

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."

Yes, I just reaslised that , I was being a bit daft.
Sounds like a good idea. And the response should be reasonable too.
Might be worth checking the pressure though.

On 16th May, 2009 Paul S said:

On 16th May, 2009 Rod S said:
But you'd better get your gear changes a bit quicker if you're thinking of taking it on a timed run anywhere

Cheeky young devil

EDIT: Actually I don't think that they are too bad considering that the clutch bites at half inch off the floor. Plus I was not trying.

The gear change is the downward slope of the MAP curve. By the time it goes back up, the clutch is out and you are back on the throttle.

But at about 1 second a change, it needs improving.

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

Have you noticed from the log how there is 150 degrees C difference in the EGTs between inner and outer cylinders?

I don't think that EGT data is of any use with the centre siamese exhaust port.

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."

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

The thermocouples fit into the gas stream through comp fittings. I've set the end about 1cm from the port wall, so they should be giving accurate data.





I'm going to swap them around before I take another log to just check that one has not gone astray.

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."

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

These are the thermocouples:

http://www.tcdirect.co.uk/deptprod.asp?deptid=190/1

I used the 3mm by 150mm ones. They do the compression fittings as well.

Edited by Paul S on 17th May, 2009.

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."

Just went out for a run in this car.

I'd forgotten how well it is running. For a highly geared 998, it's a real blast.

Just need the pending version of the new code and we will fit the turbo.

We might end up mapping it on the way to Stratford.

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 loaded the interim version, ie, with the overlapping pulses glitch fixed (but not yet with the single pulse). ???

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."

Just read this through, I've been trying to follow what you are up to and I think I'm 75% there, real impressive stuff, hats off to you for all the work that has gone into this.

The hybrid mode is now available. Have a look at the msextra post for more details and the code link: http://www.msextra.com/viewtopic.php?f=91&t=31663.

Jean

http://www.jbperf.com/