Complete and total nonsense that the engine is high compression. Complete and total nonsense that such a relatively low compression NA engine is making anywhere near that power on 85% ethanol 15% gasoline.
I think you’re misunderstanding the difference between compression and compression ratio.
For one, you noted “when new”. Compression RATIO doesn’t change with wear. Compression ratio is the difference in volume in the cylinder between the piston being at the top and at the bottom of the stroke. There is 10x more physical “space” inside a cylinder at the bottom of the stroke than the top in a 10:1 compression ratio. You don’t measure compression
ratio with a compression gauge.
Wear can allow some of that air to escape past rings or perhaps valves and that will result in lower
compression, but it doesn’t change the
compression ratio of the engine.
Back in the 1960’s, every engine was basically the same so displacement and compression ratio told you everything you needed to know about an engine. Then you could say things like “You need X fuel at Y compression ratio”. Again, in the example of my Ford Focus with a 12.5:1 compression ratio; such an engine would blow up with 87 octane fuel. But because of it’s variable valve timing (the same technology which is present in the 5.3) and more advanced intake and ignition systems, it’s able to operate on 87 without any knocking.
The whole concept behind forced induction is ramming more air inside a cylinder and it’s often done with a
lower compression ratio. It’s usually more efficient to have a low compression ratio engine with a lot of boost than a high compression ratio with a little boost.
It sounds like you aren’t very familiar with E85 and the impact that higher octane fuels can have on modern engines. I shared the link you asked me to share; but there are also a lot of other resources out there. Not every flex fuel engine takes advantage of E85 (some run like absolute garbage with E85). Traditionally the ones that benefit the most are turbocharged engines because the high octane rating means they can cram tons and tons of air into the cylinder without pre-igniting the fuel and causing damage. Even though my 5.3 isn’t turbocharged, it can still vary the amount of air in the cylinder using a variable valve timing system; which means it has more air in it when running E85 (it detects the fuel using an alcohol sensor), thus, more power. If that same amount of air were present with 87 or even 93 octane regular gasoline, detonation could occur. Because; while the RATIO (change in volume) would be the same, the heat and pressure would be much higher when more air is allowed into the cylinder when the piston is at the bottom of the stroke.
Another way to look at it might be to consider that the engine is designed to run on E85 but is capable of de-tuning itself to run regular gasoline safely without damage; instead of trying to wrap your head around an engine adjusting to take advantage of E85. If you could buy 105 octane gasoline, you’d make even MORE power.
I think most of the confusion is because there are two different components at play here. BTU and AKI. E85 has a lower BTU rating than pure gasoline, meaning less energy in a quantity of the fuel. (Hence, the poorer fuel economy). If that was the only difference, then power with E85 would be reduced commensurate to that drop in BTU. However, the second factor is AKI (anti-knock index). E85 has an AKI of roughly 105, compared to 87-93 typically available in gas stations. If an engine can take advantage of a high AKI, it can OVERCOME the low BTU’s and even leap frog it to make more power.