Originally Posted by SkiSmuggs
I think the interesting thing about the graphs is that the bump in HP and torque is from 2000-3000 RPM which is where a lot of spirited driving is done. I personally don't see much above 2000 except when towing and I always use premium then.
So, recently an experiment was done by a driveability tech friend of mine... he had his diagnostic programes running on his toughbook plugged into his truck and ran a tank of regular (or as always) and then premium... both of which I belive he had "flashed" his PCM to ensure it was operating from a learning state.
First off, he says that anytime you put more than 20 liters of fuel into the vehicle, it will automatically know to learn.
When running reg At 87 the knock sensor retards as high as 3 degrees. On 91, there is no knock retarding to the timing and even advancement of timing and spark.
So in essence, this is a premium engine that has a very sophisticated knock sensor to allow to run at 87.