If that is true, why high performance car usually suggests 91 or even higher?
I'm just curious btw
I thought someone was putting me on the first time I heard it as well.
)
The more fuel and air you can put into an engine and compress it, the more power you can get out. However, the more you compress it, the more unstable the fuel becomes, at some point it detonates. Under the right conditions, this can literally blow the head off the engine.
The slower burning fuel makes it resistant to exploding under high pressure or temperatures allowing you to have higher compression without it going boom. While it sounds counter intuitive to burn slower, it's easy to compensate for by adjusting the timing to ignite it a little sooner, which is exactly what they do.
It's the ability to run higher compression or forced induction that makes more power, not anything the fuel itself is doing.
supposidly it also has to do with the engine designed for the gas, but because of the computer, there's absolutely no reason why it can't run on p00r people gas,.
You are sort of right.
Not every engine, computer controlled or not, can completely compensate for cheap gas, even if it can, that doesn't mean it will get the most from it.
Many that do compensate do it in a crude manner by simply listening for pinging/detonation and retarding the timing until it stops (this was common on older Camaros). The engine isn't re-tuned or anything, it's simply just cut off at the knees. You need to do more than just adjusting the timing to completely compensate. If it can adjust, and some newer cars can, it's still a compromise and can take most of a tank (or more) before it really learns the new fuel curve (switching back and forth is a BAD idea). Again, it's still a compromise because the compression ratio of the engine is the biggest determining factor for what octane it requires and you cannot change without altering the heads or pistons. Your asking the system to compensate and make do, not run how it was designed.
Now, here is where it gets dangerous...
In a new car, odds are this won't be an issue, but as it ages, the detonation sensors can falsely trip leading to a loss of power (older Camaros) or fail to register it entirely. You start running lower octane and the engine may not pick up that it's detonating and slowly but surely just destroy your engine (or not so slowly!). As the engine ages and carbon builds up, it becomes even more susceptible to detonation (old Camaros). Some Nissan Xterras and Forntiers are known for this and many owners switch to mid-grade gas to compensate for it, is it the right way of dealing with it? No, but it works. And no, you don't get more performance since you didn't up the compression ratio, it's simply a bandaid to keep the engine from eating itself.
Many people think fuel injected engines are complex, and the truth is, they often are actually quite crude and low on computing power. Other than Tesla, most car makers really have not embraced technology willingly, this is probably why Cadillac was so scared of Tesla, they simply do not understand the technology and they only use it because they have to.