Not sure if that is true, on my wifes Tahoe, gets around 2MPG less if I run 85 instead of 87. Never really tried 91 though.elcapitan87 said:Lets not forget what a higher octane actually does. Higher octane does nothing to increase power, rather the higher an octane rating, the more resistant to burning a fuel is. Thus motors with higher compression or power adders may require a higher octane to prevent premature detonation (ping). If your car does not ping on 87 octane you are wasting your money with anything higher. The best fuel for any car is the lowest octane you can get away with while avoiding pinging, this is true with respect to both power production and wallet protection.
Incidentally, as mentioned here, I too found better fuel economy by ~2mpg on 87 octane than I did with 89.
Likely. Old car needed higher octane fuel or leaded fuel to prevent detonation. Due equally to high compression ratios and poor combustion chamber design. Our motors have neither.shrinkydinx said:how come people say "dynoed at 400hp on 103 octane"?
they running ridiculously high compression ratios?