Tuning for Meth - a few questions

[TiredGXP]

This is for a 2010 Legacy GT, no mods other than the Cobb Stage 1 91 octane tune.

Since we only have 91 octane fuel around here, I'm looking at adding meth injection to allow more boost and a bit more timing. I'll be using the Coolingmist CMGS-FS unit programmed to begin injection at 9 pounds of boost and 3.2V on the MAF (~85 g/s of airflow, or a load of ~2.0).

At the moment I'm doing some math for mapping out the meth injection and some preliminary adjustments to the primary fueling tables to pull fuel when the meth is injecting.

Questions:
What is the purpose of the "Primary Fuel Dynamic Enrichment" table, and how does it work?

I haven't found a description of this table in the Cobb literature or from a quick search of this site. Can anyone provide some insight to this?

If it is adding fuel under load, then the values in this table must decrease the targeted AFR in the "Primary Fuel" table. If this table works as I think, commanded AFR's appear to be super rich - on the order of 9.8:1. I'd like to get this up to 12:1, if possible.

With a maximum of 17 lbs boost, tapering to ~12 at redline, what AFR are people usually targeting?

TIA

[Bill@COBB]

At the moment I'm doing some math for mapping out the meth injection and some preliminary adjustments to the primary fueling tables to pull fuel when the meth is injecting.

Questions:
What is the purpose of the "Primary Fuel Dynamic Enrichment" table, and how does it work?

I haven't found a description of this table in the Cobb literature or from a quick search of this site. Can anyone provide some insight to this?

This table is only active when the dynamic advance multiplier (DAM) is less than 1.0. Prior years had a DAM threshold below which a failsafe fuel map would be used. For the 10' LGT, the fuel target can become progressively richer as the DAM drops, dependent on the dynamic enrichment table. You can determine the fuel target as follows:
(substitute 1 for 14.7 if you are using non-standard (i.e. lambda) units):
14.7/((14.7/"Primary Fuel" map value) + ("...Dynamic Enrichment" map value * (1.0 - current DAM)))

[TiredGXP]

Thanks for the quick response. I'll have to work my way through this.

[Bill@COBB]

Generally, unless you have knock issues that are dropping the DAM, the DAM will be at 1.0, so the dynamic enrichment table is irrelevant. The "Primary Fuel" table is what you tune. The "...Dynamic Enrichment" map is essentially a failsafe map.

[TiredGXP]

I've only logged DAM values of 1 so far, so looks good.

Just found out yesterday that most of the local Mohawk gas stations are converting over to 94 octane E10 blend, so meth injection is on hold, but thanks for the responses.