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Originally Posted by wootwoot
Agreed. Perhaps we can get a tuner to explain this statement to us because I can't make sense of it.... How can 100 octane not give performance gains? And why is the engine knocking in the first place?
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As far as leveling out the knock sensors, the car was designed to run on 93 octane, or RON, and was "tested on 98" according to Toyota somewhere, I forget where. In commifornia, where premium is 91, the ecu dials back the timing so that the engine will not knock. This makes for lower numbers. When you put in the 100 octane, it allows the engine with the stock, factory tune, to run at it's full potential without pulling timing back. Therefore no power loss.
With that said, it seems they are running 100 octane fuel, but without a custom tune. IE they're running a trd intake and exhaust, on 100 octane "race" gas, but with a factory tune. They could squeeze more out of it if they wanted to by advancing the timing just a tad.
It's basically why people are able to make more power with the E85 tune on our cars. On boosted motors, it allows you to run more boost without detonation. On NA motors, like mine with my E85 tune, the timing is able to be advanced and so on, again, without risk of detonation.
As a side note, E85 has a knock rating equivalent to that of a 105 octane fuel.
All in all, running a 100 octane gas on a factory tune will simply allow the car to run the way it was designed to from the get go if you're used to filling up with 91 or 93.
Running 105, 110, C16, or E85 with a custom map tailored to that grade of fuel is what lets you push more power out!
