Cylinder pressure limits (3.5 ECO) or other advice E85

I've got a 2020 3.5 Ecoboost I recently converted to Flex/E85 with all the supporting modifications. I got a very conservative timing advance for the flex (5 degrees) and was about to make a dedicated E85 tune. I previously raised all my cylinder pressure limits for the flex tuning and hit about 600 torque. I didn't know with the increase of timing for the dedicated E85 tune if I should calibrate in the pressure limits with the possible increased pressure from timing advance. Also, if there is anything else I should be concerned with, please let me know. I'm still decently new to the tuning. I do know that around 600 torque is about my max I should request as a driver demand due to the rods and pistons still being stock.

How are you adding timing based on ethanol content? Post a tune for help.

Quote:

---

Originally Posted by Davem3261

How are you adding timing based on ethanol content? Post a tune for help.

---

Current tune is attached below.

It is a tune currently for 93/flex that only advances timing 5 degrees. Running no knock and perfect oar.

I am looking to now make a dedicated tune just for full E85.

I am reading that 12-18 is the max spark for cylinder pressure limits based on calculated conditions and it seems like a good cap to keep the engine from raising the head or bending the rods. I did not know if it needed modified or if it was a good max spark ?safety net?in case MBT spark was trying to advance it further.

16 or 17 degrees is about the limit. I would leave your cylinder pressure limit where its at and only add more timing above 5000. Your probably making alot of torque down low, adding timing above peak torque will help the rods and head gasket live.

Quote:

---

Originally Posted by Davem3261

16 or 17 degrees is about the limit. I would leave your cylinder pressure limit where its at and only add more timing above 5000. Your probably making alot of torque down low, adding timing above peak torque will help the rods and head gasket live.

---

Thank you for the info. I am hopefully going to get to the tuning this week and might chime in a few more questions if I encounter any. Hopefully everything goes smoothly.