Gasoline: Octane limitations (Part III)

In continuing in my brief discussion on gasoline, I want to look at octane. The most basic definition I can give for octane, or more specifically, the rating that bears it's name is that an 'octane rating' is an indication of how stable the fuel in question is. By stability I mean how unlikely it is that the fuel will combust when a pressure is exerted on it. This is important to engineers designing cars because an internal combustion engine compresses the air air in the cylinder, and an unstable fuel will detonate before it is supposed to, limiting the amount of compression that can be exerted. Are you all still with me?

As you might have noticed in the pictures attached to my previous post, the gas pump only offered one grade, and the octane rating of that grade of fuel was not listed anywhere on the pump. As I mention before though, the octane rating of gasoline before WWII was usually between 45-55. This low octane rating meant engine designers had to design much lower compression engines to prevent knocking or ping. As a result, engines could not produce nearly as much power as they might have, had they been designed to run on today's high octane pump gas. This is not to say higher octane fuel was not available, airplane ran on higher octane fuel as did most racecars, but for the common consumer, engineers had to detune engines to operate on the poor fuel offered.

In the grad scheme of things, this really just meant that cars were intentionally made less powerful. Sure, they weren't as advanced as the cars of today are, but the amount of power they produced was greatly affected by the fact that the fuel they consumed was of such low quality, not because they were not well designed. Take this into consideration next time you see that a 1935 Cadillac V16 with a 452 c.i. V16 engine made only 170 horsepower.