Livin’ La Vida Octane: The quest for torque and affordable, sustainable vroom

May 22, 2017 |


Most gearheads with a passion for awesome cars will make at least one pilgrimage to the Petersen Automotive Museum on Wilshire Boulevard in Los Angeles. Among it’s many charms, it’s Hot Rod heaven and speed demon dreamland, and the faithful make the Hajj.

But the real Mecca of the Muscle Car, where the Rajas of RPMs and the Titans of Torque were found, back in the day, was about a half-mile farther west along Wilshire. Specifically, on the 7th floor of the old Petersen Building at 6420 Wilshire.

That was where the Motor Trend group was located, the HOT ROD Power Tour was born in that building, and HOT ROD magazine HQd there too, plus more Mustang mags than you could count on your fingers. The Seventh Floor was the center of the Vroom Universe.

It would be difficult to convey to you the level of disdain that accreted in that building for the California Air Resources Board. President Trump could take lessons in dissing from these guys. They just HATED the culture of emissions and engine regulations that arrived in the CARB wave.

Their general attitude towards CARB was basically, Don’t Tread on Me or I’ll Run You Over.

But gearheads of the world, when you get down to it, we actually ought to thank CARB and the Low Carbon Fuel Standard. They are doing more to revive the Magic of Acceleration than possibly any other organization of comparable influence in the world.

Livin’ La Vida Octane: the hard data

If you are Livin’ La Vida Octane, good times are returning. Let’s investigate that.

In recent days. we’ve been updating some very useful industry charts relating to costs, carbon, and biofuels — and here’s another highly useful chart from the University of Illinois that looks at ethanol as a provider of cheap octane. As the UI study noted:

While certainly not equivalent to a complete mathematical treatment of gasoline blending, a direct comparison of the price of ethanol and alternative sources of octane does shed some light on the question of the marginal value of ethanol as an octane enhancer. We first addressed the issue of the relationship of ethanol prices to the price of other octane enhancers in the farmdoc daily article of January 30, 2015. In particular, we considered the price of the aromatic compounds benzene, toluene, and xylene relative to the price of ethanol. These compounds have octane ratings generally similar to that of ethanol and have a long history as octane enhancers in gasoline blends.

We updated the data using the latest CBOT wholesale ethanol prices and the most recent data from Platts on wholesale aromatics prices, which you can find here (toluene, benzene and p-xylene). The most recent data confirms that ethanol continues to be a cheap source of octane for fuel formulators.

What’s the underlying value of octane?

What’s octane worth? The easiest way to look at it is via average gasoline prices for various fuel grades. According to AAA, the most recent US average national fuel prices are:

2.358 regular unleaded (87 octane)
2.637 mid-grade (89 octane)
2.883 premium (91-93 octane)

If you prefer the wholesale prices, EIA has these, here.

1.583 regular unleaded (87 octane)
1.769 mid-grade (89 octane)
1.940 premium (91-93 octane)

Since these fuels generally vary only in octane content, you can average these prices out and discover an underlying value of 12.2 cents per point of added octane (retail) and 8.2 cents per point (wholesale).

Which suggests that the octane value of ethanol is much higher than its price. There’s 28 points more octane in a gallon of ethanol (113 is the RON+MON/2 rating that RFA notes here, compared to the standard 85-octane gasoline blendstock that refiners use) — and that gives you a value of $3.42 in retail value per gallon to the consumer in the added octane that ethanol provides, or $2.30 wholesale. The current price for ethanol is $1.48.

How does octane relate to fuel economy?

One of the best starting points is the Mazda SKYACTIV engine, since it has sharply raised the engine compression and fuel economy that you might have seen with an older Mazda 6 — yet, it’s available in a lower compression version for the US market because of the lower octane in US gasoline. So, it gives us some good comparison data.

The 2010 Mazda 6 ran on a Mazda L-engine with 10:1 compression and its EPA mileage rating was 21 city / 30 highway. Today, the 2017 Mazda 6 is running on the SKYACTIV engine with 13:1 compression and has a fuel economy rating of 26 city / 35 highway.

Mazda itself claims “significantly improved engine efficiency thanks to the high compression combustion, resulting in 15 percent increases in fuel efficiency and torque” yet cautions that US models will have 3-5 percent less fuel economy because of running on 87 octane instead of 91 octane fuels. So, you gain roughly 1 point of fuel efficiency for every 1 point of extra octane, in that scenario.

The octane value spread

How do energy density and octane relate back to fuel economy, and then to price? Do higher ethanol blends offer a weak or s strong fuel value proposition to the consumer — leaving aside the broader social benefits? Let’s put those octane, energy density and fuel price data points together.

Here’s a chart which should give you a starting point. Here, we look at retail prices based on octane levels. At 87 octane, we have the same price because all 87 octane fuels essentially are E10. When we seek 89 octane, we can buy the standard mid-grade blend from a standard pump, or pay much less to obtain the same octane by using E20 ethanol blends.

When it comes to premium fuel we can pay $2.883 to buy fuel from the premium pump, or we can get the same octane value out of E30 ethanol for $2.09.

The value equation

Let’s now take in account the fuel economy when we choose between higher octane-rated fuels, to see where the value proposition is. In our final chart, we have converted price into cost per mile. We going to use a baseline vehicle that gets 30 mpg from a standard compression engine and using 87-octane fuel. We’re going to assume that consumers are trading up to higher compression engines when they trade up to a higher-octane fuel‚ in other words, they are trading up for a real reason. And we’re going to award 1 point of added fuel economy for an extra point of octane.

(Note to readers. There are more important reasons to use higher octane ratings when running high-compression engine — primarily to avoid engine knock from premature fuel detonation, and thereby avoiding major vehicle damage. But here, we’re just looking at the direct fuel-at-the-pump value.)

So, when consumers trade up for added octane, it’s going to cost them more if they are using standard fuels, but when it comes to using higher ethanol blends, the trade-up to higher compression actually comes at a discount. You save money running a higher-compression engine on E30 than running around on E10 – looking at the data points we’ve analyzed here.

(Note to readers: Actual engine tests are the best way to determine the fuel economy of a given high-compression configuration and all the other varaibles that an engine maker can work with to produce economy or torque. So, please don’t skip any chance to get real-world data.).

The Bottom Line

By creating a market for biofuels, the Renewable Fuel Standard and the California Low Carbon Fuel Standard are driving benefits to consumers no matter what fuel blend you’re running. As we noted above, ethanol-free fuels cost a lot more, and who knows what fuels would cost if there was not a market choice? But the special beneficiary of high-ethanol blends are higher-compression engines.

Rather than facing higher costs to obtain the fuels to run on their engines, now drivers have a value choice — not just in cost per gallon, but cost per mile. And with carbon schemes shifting prices to favor high-octane fuels, there’s more vroom in your buck.

Happily, high-compression engines are better for the environment, because they promote fuel economy through higher work efficiency. And here’s a special benefit. High-compression engines have more torque, that’s one of the reasons we love them — the kick that makes you feel like you’re in a race vehicle.

So, you get torque for nothing.  So, when you’re enjoying that incredible extra acceleration and power – just remember that the muscle in your car is actually better for the environment, and provides domestic jobs.

So, accelerate in peace.

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