The Octane rating is used for one thing, and one thing only: to measure the
percentage of octane to heptane, or the ability of the gasoline mixture to mimic a similar octane/heptane ratio.
It just so happens that those ratios of octane to heptane have a generally accepted ability to resist spontaneous combustion at a given compression ratio.
This does not take into account the ambient air tempreature, the load on the engine, and the heat already generated by the motor from previous pre-ignition (ping/knock/detonation/spontaneous combustion).
The Solara motor (V6 in my case) does have a knock sensor that compensates for having to use (against the manufacturer's recommendation) sub-premium fuel. This is not recommended because of the following:
As to the assertion that higher octane results in lower gas mileage (probably because you use the 100 to drive faster, which results in lower gas mileage - not the octane rating but your lead foot), and that increasing octane ratios does not result in higher mileage OR better performance, the purpose of high octane fuels is that they enable high compression ratios to be used. Higher compression ratios give increased power output and improved economy (assuming the same engine displacement and other aspects). The octane number requirements for a given compression ratio vary widely, but typically a compression ratio of 7.5:1 requires 85 octane fuel, while a compression ratio of 10.0:1 requires 100 octane fuel. The V6 has a 10.6:1 compression ratio, so the knock sensor is already working overtime.
Raising the octane level of your fuel will primarily help prevent knock. If your engine is not currently knocking, you won't see any significant advantages of using higher octane fuel. On the other hand, if the engine is designed from the beginning for higher octane fuel (and ours are!), it will have considerable advantages in power and economy. Since the knock sensor retards timing to prevent spark until after TDC, you are losing a percentage of the power stroke to retarded timing with lower octane ratios, and thus losing the full power stroke per cylinder of fuel burned. Since you are not getting full power, you therefore have to use a greater quantity of gasoline to go the same distance. Again, since you are losing a part of your power stroke to retarded timing, you are losing the engine's ability to completely burn the fuel, so you lose power and mileage again.
Over time, you also clog up the exhaust channels with partially burned fuel (from the cylinder head up to the catalytic converter, which has to work overtime). This clogging constricts the exhaust channels and will then result in lower power and inefficient fuel burn.
Lemme ask you: Why do race drivers use higher octane mixtures if there is no power advantage?
Compression, which we got, requires higher octane fuel, or you end up being retarded!
way to go man lol
