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Blog: Ethanol advantages outweigh Btu

By Susanne Retka Schill | September 12, 2016

Whenever I blog about ethanol’s value as a fuel, there’s usually a comment about how ethanol has 30 percent less energy than gasoline, concluding that it’s obviously inferior for that reason.  In looking it up, E100 has 76,100 Btu per gallon, compared to 114,000 Btu per gallon of gasoline. For an E10 blend, with its 111,836 Btu per gallon, the difference in energy content is minor—it probably has less impact on mileage than whether the tires are properly inflated.

What I’ve been wondering, though, is just how helpful a Btu comparison is. After all, an internal combustion engine isn’t burning fuel like the burner on a stove that raises the temperature of water by one degree (which is what Btu measures). And, I’ve often heard how you can get more torque and horsepower from ethanol.

I gave Dan Schwartzkopf a call to help me understand better. He has long been an ethanol supporter, working for two decades or more in the racing world, helping to tune performance vehicles to optimize ethanol blends.

I asked if Btu was really relevant, since the fuel isn’t actually burned, but exploded. He corrected me on that misconception. “There is a burn across the cylinder. You think it’s exploding, but we try to get an even burn of the fuel across the cylinder with ignition. Sometimes explosions happen when the fuel is not right.” 

We didn’t talk about knock or ping, but that’s that the common name for those premature explosions. The website I looked that up on said, “One of the causes of engine knock is sub-par gasoline—low quality and low octane fuel can cause a whole cluster of problems, such as increased combustion chamber temperatures and higher cylinder pressures.”

So yes, ethanol has lower Btu, but it has other properties that compensate, Schwartzkopf said. “Oxygen content for one, which relates to all the benefits of emissions. You don’t have the hydrocarbons. You don’t have the aromatics like gasoline, which create toxic emissions. Ethanol is clean burning. That’s why oil companies really like adding ethanol. They can put their junk gas, with all these aromatic additives in there and they add ethanol and it reduces emissions, so it makes them look better.  

“I’m a race guy. To put it simply the benefit of ethanol is the oxygen, the octane. Ethanol carries a way superior octane. It allows for that burning effect, even though you’re putting more fuel in the cylinder.”

“In performance world, we get proficient, we’re able to utilize the total fuel we put in. Flex-fuel cars are flexible. You never get the same mixture each time at the pump. You might get E50 or E60 or E70.  You might be getting E85, you don’t know.  There’s an oxygen sensor that allows the fuel mapping to change and it’s kind of sloppy. That’s why FVVs get less mileage, cause it’s a sloppy tune-up. But when you get into efficient performance engines and you use the ethanol – it’s not as great as difference as everybody makes it out to be.  The percentage shrinks, because these engines are precisely tuned and they take advantage of everything you’re putting in them.”

Another advantage to ethanol is that is burns cooler, he said. “It has a cooling effect when you burn that ethanol because it burns so rapidly, you don’t have a heat soak into the engine – you burn and it exhausts. You don’t have that time for saturation of the heat.”

“Ethanol beats gasoline because you can get more power on the racetrack or in the performance world. Alcohol fuels are superior because they are oxygenated, they’re cooler, they’re quick burning  and because of the extra volume you use over gasoline, you carry the equivalent to or more Btu than gasoline. It makes more horsepower and it’s because it has a superior octane rating. There’s less wear and tear on your engine, you’re reducing the carbon deposits. It’s more economical.  When you start figuring: I don’t have the engine repairs I used to because I don’t have the carbon deposits; I pay less at the pump; I may give up a couple miles to the gallon but, you know, my overall savings is really probably better.”

In the performance world, anything that gives a racer an advantage is embraced pretty quickly, Schwartzkopf said. His mission these days is to help racers learn how to take full advantage of ethanol blends.