Dual spark map question???

[nitrorocket]

I run a custom O.S. 3 with a twin turbo LS1. I run 18.5 psi of boost on 93 octane. My question is....With the dual spark maps enabled, does it run off the high octane table untill KR is present??
I am wondering if I could enable this in case I were to ever fill up with a lower octane. I dont want my timing to change unless KR is detected while I am truly running 93 octane.

I am assuming that there is no way to do this safely. I would be relying on knock sensors to detect from blowing my motor to the moon. Also, if KR were detected at wide open throttle under full boost, I am sure it would be too late to stop and control detonation.


What is the difference between this, and the timing KR will pull out if KR is detected???
Any info or thoughts???

[Tordne]

There is an Octane Scaler (GM.ASPARK) which balances between both the High and Low Octane Tables.

Generally the parameter should be at 100 meaning that it will read solely from the High Octane Table. As KR is detected and above another parameter it will degrade the Octane Scaler towards 0. In the absence of KR it will come back up towards 100 again.

This is how the Octane Scaler balance works:
100 - Spark number gained only from High octane Table
50 - Spark is balanced 50/50 between High and Low Octane Tables
0 - Spark number gained only from the Low Octane Table

Any number like 89.73 will be a variable amount between High and Low.

Cheers,

[nitrorocket]

So basically with the already active KR timing reduction, the Low octane spark map is just for low fuel and open loop malfunctions in a stock setup.

Correct? Otherwise I do not see a use for it!

[Tordne]

The dual spark maps (while running Speed Density) are only available in the EFILive Custom OS's. In a stock OS if drops to the Low Octane Table.

It is really there are a means to balance/reduce timing between the two tables in the event that you run lower octanr or get a bad batch of fuel I guess.

In the Custom OS you can also use the Forced Octane Scaler (A0000 & A0001) parameters as well if you want to lock to the High (or Low Ooctane) Table.

[nitrorocket]

Question is, the KR timing retard does the same thing without the low octane table, so I am not understanding the low octane table. Does it default to this table for a longer period of time thinking it has low octane because of knock and will have to stay there??

[Tordne]

Nope. The Octane Scaler will try and get back 100%. So as it rises and KR is found to occur the scaler will degrade again favoring the Low Octane Table some more.