New knock control tables
Posted: Tue Aug 30, 2011 1:45 pm
I'm interested in using the new knock control tables in version 1.5.1.0, just in case I get a bad tank of gas, but just want to check my understanding first. I have read the help file several times and understand what is known of the Honda setup, but with the Hondata 'knock ignition limit' table being relative to the main ignition tables its a little more complicated. My current kal was tuned without knock control, so I realise I can't just enable it without it changing the timing the engine will run.
The way I see it, to run the stock knock control setup I need to adjust any part of the main ignition tables in my current kal where there is a negative value in the 'knock ignition limit' table. To run the same ignition value under knock free conditions I need to add (advance) the main ignition value by this negative amount. So, for example if I have +27* in the main ignition table before I enable knock control, and the value in the 'knock ignition limit' table is -1.4*, when I enable knock control I need to change the main ignition value to +28.4*.
If the knock retard table at this point in the kal is 10*
under knock free conditions I will get:
Ignition advance = minimum(MBT Ignition, knock ignition limit - (knock retard x knock control)) = minimum(28.4, (28.4 - 1.4)-(10 x 0)) = 27*
With enough knock to give a knock control value of 50% I will get:
Ignition advance = minimum(28.4, (28.4 - 1.4)-(10 x 0.5)) = 22*
Am I correct?
It seems that in this calculation the magnitude of the value in the 'knock ignition limit' table is not important, it is only relevant whether it is positive or negative. Presumably the magnitude is important in other calculations we don't know about so I will go by the rule of thumb to "use low values where the engine is likely to knock".
The way I see it, to run the stock knock control setup I need to adjust any part of the main ignition tables in my current kal where there is a negative value in the 'knock ignition limit' table. To run the same ignition value under knock free conditions I need to add (advance) the main ignition value by this negative amount. So, for example if I have +27* in the main ignition table before I enable knock control, and the value in the 'knock ignition limit' table is -1.4*, when I enable knock control I need to change the main ignition value to +28.4*.
If the knock retard table at this point in the kal is 10*
under knock free conditions I will get:
Ignition advance = minimum(MBT Ignition, knock ignition limit - (knock retard x knock control)) = minimum(28.4, (28.4 - 1.4)-(10 x 0)) = 27*
With enough knock to give a knock control value of 50% I will get:
Ignition advance = minimum(28.4, (28.4 - 1.4)-(10 x 0.5)) = 22*
Am I correct?
It seems that in this calculation the magnitude of the value in the 'knock ignition limit' table is not important, it is only relevant whether it is positive or negative. Presumably the magnitude is important in other calculations we don't know about so I will go by the rule of thumb to "use low values where the engine is likely to knock".