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jbelanger

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Montreal, Canada

I thought I should answer Dave's question here because it might be of interest to others.

On 12th of Feb, 2007 at 02:39pm TurboDave said:
I'd appreciate to know what you've done on the staged injector side.
Have you got it as a simple 'switch on and half pulse' system for when the second injector comes on line? If so, is there any 'gain' adjustment for this change-over point? I suspect this will be needed, as there is a difference running two injcectors at half the pulse width of a single injector; which will be even more amplified by the larger injectors we'll be running on out engines for big power.

The staging algorithm for the siamese code is the standard MS2/extra one and it is pretty elaborate. It allows you to set the staging with respect to 1 or 2 parameters out of 3 possibilities (RPM, MAP, TPS). You set the threshold at which the staging goes on and once this threshold is reached (or both threshold is you chose 2 parameters) staging is on and both injectors are used with the reduced pulse width. There is also an hysteresis parameter so that staging doesn't go on and off too quickly.

Also, you input the primary and secondary injector sizes so that the pulse width when staging is on is not necessarily just half but it is correctly computed with the ratio of the injector sizes.

Finally, the transition between staging off and on can be gradual. This means that the pulse width of both injectors will not go from full pulse width for one injector and zero pulse width for the other injector to reduced pulse width for both injectors but will gradually go between those values. You can decide how fast the transition is by giving a number of ignition events. This can help to smooth out the transition between staging off and on for certain configurations.

If you download the Megatune software and the MS2/extra ini file, you can play with it and look at all the different menus to give you an idea of the MS2/extra features and how they can be configured. For the moment the changes for the siamese code are minimal but they will become more important in upcoming versions.

Jean

http://www.jbperf.com/


RogerM

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I like nice quiet girly Minis

Cheltenham, Gloucestershire

Will take a fair bit of experimentation to get it all sorted but it does look liek tehy have it pretty well sorted. A couple of odds I'd like to see done differently but then I am a picky sod, would also require blending between two maps etc ..... maybe for the next version!!

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

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

On 27th of Sep, 2007 at 12:45pm Jimster said:

why do you you think I got a girlfriend with small hands?


jbelanger

1267 Posts
Member #: 831
Post Whore

Montreal, Canada

If you use RPM and/or MAP and you set the injection table such that you have one row and/or one column which correspond to the threshold(s) then you don't really need 2 tables because you will be using 2 different parts of the table when staging is on or off.

If you want to use 2 tables, you can do it because there is a dual-table mode but then you don't have thresholds and you have to adjust the tables to do the blending as you want it which is a lot more complicated and time consuming.

By the way, I'm using the word table instead of map because that's the term used in MS documentation and there is less chance of confusing it with MAP (manifold absolute pressure).

Having said that, I would be interested in reading how you would go about doing the staging. And depending on how complex it is, it might be worthwhile to implement it if there are noticeable improvements over the current method.

Jean

http://www.jbperf.com/


TurboDave16V
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SouthPark, Colorado

Cheers Jean,

D

On 17th Nov, 2014 Tom Fenton said:
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