What is octane? [INFOGRAPHIC]

Octane is in the news and gaining steam. It likely will be a crucial component of the next round of fuel-economy standards (collectively known as CAFE) for the nation’s fleet of vehicles between now and 2025, a set of rules to be crafted by two federal agencies and California’s influential Air Resources Board. But what is octane, exactly?

We’ve discussed the term, and the wide-ranging benefits high-octane fuels can bring for the public, in previous posts on the Policy CAFE page. But until now we’ve never had a simple, easy-to-understand visual tool that explains the basics.

Here ’tis, suitable for sharing, discussing and framing:

what is octane

For a more detailed discussion, check out our blog post on this topic here.

3 replies
  1. JeffH
    JeffH says:

    You’ll have to take this conversation a bit further.

    Yes, alcohol has a higher resistance to ignition (some sources claim 115 octane), but lower energy density. The problem today with Flexfuel vehicles is that E-85 (115 octane) is not efficient in a gasoline engine (89 octane) and results in lower performance and mileage.

    The community ALREADY has a choice, and most choose NOT to burn E-85

    There is hope, however. Newer direct injection, forced induction engines are able to effectively increase compression ratios for gasoline and alcohol, without dreaded detonation.

    Another alternative, of course, is to have a purpose-built E-85 engine.

    Is it widely known that ethanol was the FIRST octane booster discovered? Before tetraethyl lead? But could not be produced commercially in sufficient quantities to support the gasoline industry?

    Reply
    • Landon Hall
      Landon Hall says:

      Thanks for the well-thought-out comment. E85 burns best in engines tuned to run on it (flex-fuel vehicles), but the automakers are saying they need a higher-octane fuel (beyond the standard E10) to design the high-compression engines needed to reach future fuel-economy thresholds. … The public has not had a choice, not in a meaningful way. Sure, ethanol was once the additive of choice at refineries, and you may be right that it couldn’t scale up at the time. Another possibility is that the oil companies couldn’t make any money off ethanol (which was not a proprietary product … anyone could make it), so they didn’t pursue it.

  2. Ryan
    Ryan says:

    I have to disagree with the first reply we have never had a car on a dyno or had feed back as to a loss in performance using E85 with our products, always quite the opposite. Especially in hot climates gains can be amazing. The only draw back we see is lower milage, but without spending anymore than buying gas if you use premium.

    Reply

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