Amount of ignition advance required is only relevant to combustion rate.
Peak power happens when peak cylinder pressure occurs @ 15 degrees AFTER TDC(some sources claim 16 or 17). It actually takes time from when the spark occurs until the flame has engulfed the chamber and created peak cylinder pressure.(Flame propagation in technical terms)
PCP is a critical point. If it occurs before 15 ATDC you risk damage from detonation. You dont want PCP occurring at TDC and certainly not before that. PCP occuring much later than 15-17 degrees ATDC WILL cost you power.
A whole bunch of factors determine actual combustion rate. To name a few...chamber design, piston design, quench, the fuels resistance to burn(octane), charge temps, heat of compression, cylinder head temp, water temp, air/fuel mix.
The amount of ignition lead required to acheive full flame propagation for Peak Cylinder Pressure(PCP) to occur is directly tied to how fast the combustion rate is.
E85 is a whole different animal than gasoline at same octane rating. Ethanol at a "race mixture" burns slower. The low octane gas portion of E85 is there to help light the fuel on cold starts. That said it still doesnt cold start as well as race gasoline. The ethanol has a cooling effect on charge temps in the cylinder, methanol in rich race mixtures more so.
Hope this helps you understand why your friends Toyota motor might only need 11 degrees of timing to your 27.
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