Octane rating is based upon the same assumptions, then and now. However, the way it is tested for today seems much different than when I went to an U.S. Army school to learn "petroleum, oils, and lubricants" testing including octane rating of gasoline.
99 Octane essentially means, that gasoline burns at the same speed as a mixture of 99 parts iso octane gasoline and 1 part benzene gasoline. Bottom line is the new premium fuels may knock, ping, and make your car overheat because that fuel burns to fast and "bangs" in the combustion chamber before everything is ready. Thus less spark advance or an additive. Higher compression also causes the fuel to burn faster, thus lower compression ratios in the newer cars. Computers and engine management systems can help burn the new stuff in higher compression engines and supercharged and turbocharged engines.
That's about all I know, I hope it helped.
Russ
http://albums.photopoint.com/j/View?u=1595962&a=12199293&p=44747301.JPG
99 Octane essentially means, that gasoline burns at the same speed as a mixture of 99 parts iso octane gasoline and 1 part benzene gasoline. Bottom line is the new premium fuels may knock, ping, and make your car overheat because that fuel burns to fast and "bangs" in the combustion chamber before everything is ready. Thus less spark advance or an additive. Higher compression also causes the fuel to burn faster, thus lower compression ratios in the newer cars. Computers and engine management systems can help burn the new stuff in higher compression engines and supercharged and turbocharged engines.
That's about all I know, I hope it helped.
Russ
http://albums.photopoint.com/j/View?u=1595962&a=12199293&p=44747301.JPG
