[BYprodriver]

Originally Posted by jcb986

I built street cars back in the 60's and I would mix premium American White 93 octane with Sunoco Blue Plus also 93 octane. These were leaded gasoline, anyway you could feel a change in how the engine ran and the mix also changed the smell of the coming out of the tail pipe. When I went to drag strip I would mix airplane fuel to gas. I was running a 327 Chevy engine, 12-1 pistons, polished and ported heads and high lift street Crane cam. My best guess was my octane was around 105. Engine screamed and it performed perfectly. If you are using racing fuel you would be disqualified. Racing fuel has very unique smell. So octane makes a big difference high performance engines.

I built muscle car engines in the '80s & the best pump gas was Amoco 93 which was white/clear. If cylinder pressure was high enough to cause preignition or detonation I would add 130 octane low lead "blue" aviation fuel. Avgas lacked some lubrication additives that road gas has, so I also added Marvel Mystery oil. Experimented with the Cox model fuel & mothballs that were 100% Naptha. The Amoco 93 had a very distinctive exhaust smell, & so does the Avgas. I'm guessing the American White 93 became Amoco later.