For the energy balance, your main inputs are the energy from the fuel (energy density of fuel x mass of fuel) and energy added from the compression stroke compressing the mixture. The main outputs are heat loss through cylinder ( cylinder walls, head, piston, etc.), frictional losses, the work done by the piston moving, and whatever is left is what's going out the exhaust as heat energy.
E85 has an energy density around 29.7 kJ/g, while gasoline is around 46 kJ/g. So per gram of fuel, e85% has about 35% less energy. However, you need more fuel to hit to hit stoic with e85. For example, assume an engine consuming 100g of air. To hit 14.7 stoich with gasoline, you need 6.8g of fuel. To hit 9.7 stoic with e85, you need 10.3g of fuel. This is 3.5g, or 51% more fuel (mass basis, not volume). So with e85, you have about 35% less energy per gram, but you need about 51% more fuel mass at the same airflow and stoichiometry - this is a net energy gain for the system running e85 (at same mass air flow and stoichiometry).
I don't know how the combustion temperatures differ from e85 to gasoline, but that will be a factor in cylinder pressure generated during combustion.
As far as lifting the cylinder head, I'd correlate that mostly to the torque the engine is producing, as that is directly related to cylinder pressure, which is what would lift the head. E85 is more knock resistant, so you can run higher engine loads (airflow expressed as a percentage of cylinder fill per stroke), and therefore higher torque/power with e85. So you have a greater potential to lift a head with e85, but that's mostly because it allows you to push the engine harder.
EDIT: I forgot a key output in the energy balance above, which you touched on - work done by the piston pushing against exhaust gas pressure during the exhaust stroke. Back pressure is a killer!!!
