I would think the stock manifolds probably heat up the EGT's a bit. Wonder how much that changes with new tubular manifolds.The right air fuel ratio is the one that delivers peak torque with the correct Exhaust Gas Temperature.
Put an EGT gauge in an E85 burning VR38DETT and you will some interesting results!
You definitely don't want to run too rich on E85.Most times I see 12.0-12.2 as measured on the car's O2 sensors on e85. A conservative tune will have them at 11.8.
I read that as well so I decided to call Cobb to get the scoop. From what they told me, if you are an ATR user this will not affect your 'Fuel Low Det' tables so if you were commanding 12.22 before that number will stay the same. As you stated, the only change should be that 'AFR Old' is no longer used and "Air/Fuel Ratio" is now used and should better approximate the actual AFR value. I would personally want to verify this using an aftermarket wideband to understand the offset for my vehicle. I think Cobb is going to post something about his in the Cobb forum.Fwiw Cobb has done away with AFR "old" in newer versions of the software and now "Air/Fuel Ratio" more closely mimics the tailpipe AFR. Accordingly it's not a good idea to target 12.2 in the tables on the newest revisions of AccessTuner.
EcuTek's AFR is similar to this.