Originally Posted by dpando1
Yeah if ever, but right now I am kinda frustrated because I was averaging atleast 29 now Im getting a flat 27...but the car is so much more responsive.
I have NEVER run 91, I honestly do not see the point since our car is meant for 87. And from what I understand higher octanes are used purposefully to prevent engine knock at higher compression ratios which I understand our car has a 12:1. Is it really worth buying more expensive gas?
12:1 would be an incredibly high compression ratio on 87 octane if it wasn't for the Gasoline Direct Injection and the twin independnt variable camshaft timing.
The injection of liquid fuel directly into the cylinder cools the compressed air charge and helps to prevent detonation, as well as the variable cam timing retarding the combustion cycle enough to prevent spark knock for the most part. It does this by sacrificing a measure of power and performance that could be gained with advanced spark timing. 91-93 octane fuels are more resistant to pinging and detonation/ pre-ignition and therefore the car can adjust timing accordingly in order to make more power from the same quantity of fuel consumed.