Why Octane Matters To Your Engine
- News Staff @ AutoGuide.com
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You have a choice when you pull up to the pump. Most gas stations have three choices for fuel for your vehicle, based mostly on octane ratings. Which one is the best for your vehicle? A lot of that depends upon your engine, but one thing is clear, not all high-octane fuels are created equal and one in particular stands apart from the crowd – Sunoco Ultra 94. And while you may hear opinions to the contrary, octane ratings really do matter to your engine.
What is Octane?
Octane is a rating for fuel stability that comes from a specific hydrocarbon, 2,2,4-Trimethylpentane which is commonly called isooctane, that serves as the basis for rating fuels. This molecule became the standard for ranking fuels, and is most commonly related to engine knocking. Knocking occurs when the fuel/air mixture doesn’t combust at the right time during the compression cycle. When your piston is moving inside the cylinder, the incoming fuel-air mix should be ignited by the spark coming off the plug. Lower octane fuels can allow combustion to start from the compression process rather than the spark plug. Too early of combustion creates extreme pressures inside the combustion chamber because the engine isn’t ready to accept the power. The piston rattles in the cylinder and makes an audible noise.
How knocking relates to octane ratings has to do with compression. The piston compresses a cylinder full of fuel and air into a minimal volume prior to ignition, and it is based on each engine's specific compression ratio. This compression creates heat beyond that from the actual ignition of the fuel mix. The octane rating of fuel is a measure of the heat resistance of the fuel to ignition. In other words, higher octane fuel will withstand a higher compression ratio and not prematurely ignite. It is a common misconception that you will get more power simply from using a higher octane fuel. On the contrary, using a higher octane fuel like Sunoco Ultra 94 allows you to get the full potential of power from your higher compression motor.
Why it Matters
There are a couple of ways to look at just why octane matters to you. For those of you lucky enough to have an old muscle car from the 60s and 70s, who have a built-up, higher compression motor, you want the highest octane fuel you can get, said Zachary Santner, a Senior Quality Specialist with Sunoco Race Fuels. The highest octane sold at gas stations that you can buy at the pump today is Sunoco Ultra 94.
“When you look at readily available fuels at the gas station, your octane range is typically 87 to 93 in some cases,” Santner said. “It is really a measure of how much heat and pressure can be put on the air/fuel mixture in the cylinder before ignition. If you have ignition at the wrong time, you wind up with a piston being pushed back down as it is trying to come up, and you have engine components there, and you just break something.”
But higher octane fuel relates to current vehicles, too. Current vehicles with higher performance motors need higher octane fuel as well, Santner said.
“The ability to handle the higher heat and pressure gives the fuel stability that lets the engineers and designers with the automotive manufacturers extract more power out of the same fuel,” he said. “The energy content, the BTUs are the same as lower octane fuel, but the efficiency curves within engine dynamics means that the higher compression ratio you have in the engine, the more efficient the whole process, so you are getting more power from the same BTUs. But to do that, you need more stable fuel.”
With the current trend toward smaller engines with turbochargers and direct injection technology, more and more vehicles are able to make more power on premium fuel vs regular grade. This is where Sunoco’s Ultra 94 fuel comes into play, Santner said. Ultra 94 being the highest octane, Top Tier premium fuel that you can buy at the pump provides quality and performance for your engine. This is especially important for those of us that like to do a little spirited driving, but it also applies to driving in hot weather. It’s easier than you might think to get a little past what the engineers who designed your motor intended for optimal performance ranges. Ultra 94 will give the engine a little more added protection from fuel detonation, letting you have your fun.
Sunoco Ultra 94 fuel has limited availability that is increasing to more markets. If you’re wanting to add the highest octane rated fuel to your tank so you can let your right foot do the talking on the road or the track, go to the Sunoco Ultra 94 website to see if it is available near you.