Dwell question

[contectr]

Hondata,
i have try a little measure at engine warmed at idle with my bosch oscilloscope and my bosch clamps 30A on 3 mS, 4 mS and 5 mS on calibration for see how work the dwell correction on Honda ecu.

The first is a 3 mS set on calibration



And the oscilloscope give me this result



About 2 mS

The second test is a 4 mS on calibration



And the oscilloscope show



about 2.5 mS

The last test was at 5 mS



and the oscilloscope show



about 3 ms..

Why this?
There are a hidden compensation table??

[contectr]

Hondata, i have try few test with my bosch oscilloscope and i have found this value

- 7 mS setting on the calibration, real dwell readed by the oscilloscope is 5 mS
- 5 mS setting on the calibration, real dwell readed by the oscilloscope is 3 mS

Do you have any answer?!

I have another question, with the ls coil that i'm ready to use, i need to set the dwell real ( readed with the oscilloscope) at 5 mS..for have this real value i need about 7 mS on the calibration. This because the ls coil need a long charge time for Give the best performance.
At 6500 Rpm 7 mS is 273 degree ...i have try and i see the max value for degree cranck dwell is 254..

This max value is a Kpro software limit or is the Honda ecu limit?
Can you modify this max value?

[Spunkster]

Our software designer is out of town until late next week so you will have to wait until he returns for an answer.

[Hondata]

How are you converting the duration to time? What is the battery voltage when you are doing this?

[contectr]

Hondata,
i convert the dwell ° to dwell mS with this formula:

Dwell mS= Dwell° / (6*rpm)*1000

The measure are done with the engine warmed at idle 1000 rpm and the battery voltage on Datalog are 13.90 Volts.

This is the same measure with ls coil and on the black line you can see the voltage readed by the oscilloscope



There is any hidden table unlocked that have a % of correction?
And the issue of can't digit a value over 254 °dwell is possible to modify?

[contectr]

Hondata, do you have any news about this?!

[Hondata]

The unit is incorrect. It is not crank degrees, but is percentage x 10.

eg a value of 100 gives 10% dwell, or 12ms @ 1000 rpm.

This should match your measurements. Thanks for pointing this out, we'll change the unit for the next release.

[contectr]

Hondata,
Ok for this but our example :

If at the breakpoint 600 rpm and the table the value is 18 the dwell is 18/600 *100 = 3 mS?!
And for 6000 rpm with value of 110 the dwell is 110/6000*100= 1.83 mS?!

and for the issue about i can't charge my coil over the 254 value can you fix this?
Because i need a flat curve of dwell real at about 4.3 mS for have the maximun performance from my coil..

[Hondata]

The maximum dwell is just over 20%. We've made over 1100 hp on stock coils, so they do have enough energy for any application.

[contectr]

Hondata,
Ok for the stock coil good for over 1100 hp with race gas.
The stock coil at 3 mS of dwell are near the saturation point with about 8.5 A of current on primary circuit. The stock coil have 2.2 mH induttance and with this formula can calculate the energy spark:

E= 0.5 * C^2*I

So about 80 mJ of spark energy
But at this dwell and voltage battery 13.5 the coil are near the saturation and they heat a lot.
With the Ls coil with an 4.8 mH of induttance at 4.3 mS they have about 7A on primary circuit.

So about 117 mJ of spark energy.
The ls coil at this dwell are in very safety range and they don't heat.

When you injection are water/methanol or pure water, you need a very strong spark energy for burn the mixture.

Sorry but i don't understand...
The dwell is not only over the 20 % because at idle the stock dwell is 14 and if i add 20% i have 17..i'm able to insert a value of 254 at idle

If i want to calculate the dwell on mS wich mathematical formula should i use?!
Because if the number in the table are a percentage *10, when i have 18 at 600 Rpm what is this?
The 180 of 600 Rpm ?!

Dwell mS = number in the table/Rpm * 100 ?!

[Hondata]

18 @ 600 rpm would be 1.8%, which would be 60*2/600=200ms * 1.8% = 3.6ms

[contectr]

Hondata, now this look clear...
And for the maximun value used on the table can't modify them?

[Hondata]

Sorry, no, Honda has limited it to 20.8% duty.

[contectr]

Ok Hondata, Thanks a lot :-)

[contectr]

Hondata,
in the dwell table the max value is 254 that's is the 25.4% and at 9000 rpm is 3.39 mS.
If i set my 0 on voltage compensation table at 16V and set at 14 V a +47.5 % the ecu compensate and give me 5 mS dwell or the limit is physical on the Honda hardware?!