There is no "perfect" air/fuel ratio.
Each engine will like a slightly different value, since the BSFC (a measure of efficiency making power from fuel) will be different.

But with a Ron's alcohol injection, a good starting point is
Lambda = 0.835
Methanol scale = 5.35 (5.2 to 5.5)
Gasoline scale = 12.3 (12.0 to 12.6)

What values have you seen on the track so far?

I highly recommend talking to James or Scott at www.killerrons.com