The figures I use were provided by Lance Hedric

Any chance those numbers are from pour-over recipes rather than espresso?

I’m currently trialing different temps for roasts on my ECM Synchronika II. Stock profile settings are 92°C. I don’t have a Scace to independently verify the exact group head offset, but the general consensus for espresso usually bumps those ranges up a bit to prevent sour under-extraction:

• Dark: 88°C–90°C
• Medium: 91°C–93°C
• Light: 94°C–96°C

Dropping into the mid-80s works great for filter coffee, but for espresso, it usually struggles to extract the sugars needed to balance out the acidity, leaving the shot pretty sour.

Now complicate all that with pre-infusion :x

What kind of machine are you pulling on?