Premium gas comes with a 90 plus octane rating that averages out to about Fuels of different grades will not burn the same way. The less octane a fuel contains, the easier it burns. For modern vehicles equipped with an engine control module, the computer uses sensors to determine the optimal air fuel ratio.
The computer uses a knock sensor adjust ignition timing to stop detonation. So in some cases you may get a slight boost in performance by using a higher octane fuel. Although all grades of gasoline produce similar levels of heat power, their rates of combustion can vary. The grade of a fuel lets you know how readily it will combust inside of your engine.
Fuels with lower levels of octane usually burn faster and stronger when they are pressurized, which produces a ticking or knocking noise in your motor. It may also void your warranty. In older vehicles, the engine can make an audible "knocking" or "pinging" sound. Many newer vehicles can adjust the spark timing to reduce knock, but engine power and fuel economy will still suffer.
It depends. For most vehicles, higher octane fuel may improve performance and gas mileage and reduce carbon dioxide CO 2 emissions by a few percent during severe duty operation, such as towing a trailer or carrying heavy loads, especially in hot weather.
However, under normal driving conditions, you may get little to no benefit. If your vehicle requires midgrade or premium fuel, absolutely. If your owner's manual says your vehicle doesn't require premium but says that your vehicle will run better on higher octane fuel, it's really up to you.
The cost increase is typically higher than the fuel savings. However, lowering CO 2 emissions and decreasing petroleum usage by even a small amount may be more important than cost to some consumers. The sale of 85 octane fuel was originally allowed in high-elevation regions—where the barometric pressure is lower —because it was cheaper and because most carbureted engines tolerated it fairly well. This is not true for modern gasoline engines. So, unless you have an older vehicle with a carbureted engine , you should use the manufacturer-recommended fuel for your vehicle, even where 85 octane fuel is available.
Ethanol has a much higher octane rating about than gasoline. Refiners usually blend ethanol with gasoline to help boost its octane rating—most gasoline in the U.
Ford Motor Company. Szybist, J. SAE Int. Fuels Lubr. Stein, R. Polovina, K. Roth, M. Foster, et al. Leone, T. Olin, J. Anderson, H. The rush to 60 mph softened to a still-blistering 5. Tapped into the Ford's CAN bus, we recorded a peak boost pressure roughly 1. The high-octane gas also helped when soft-pedaling the accelerator, elevating mph fuel economy from That won't make a financial case for running 93 octane, but then you didn't buy the expensive engine as a rational choice.
You can think of this EcoBoost engine's more aggressive high-octane tune as a sort-of sport mode that can be switched on or off with every fill of its We always assumed that mid-grade fuel existed chiefly to bilk a few more dimes from the type of people who ask the dealer to undercoat their car.
Turns out it's also for owners of Fiat Chrysler's Hemi 5. With no mention of that on the fuel-filler door, though, a driver would have to read the manual to know.
With just miles on the odometer and looking as if it had already been hand washed with grit sandpaper a half-dozen times, this Charger is unlikely to ever taste 93 octane again.
Oh well. The Charger's manual says 87 octane will provide "satisfactory fuel economy and performance. Similar to the BMW, the Dodge's gains on the dyno 14 horsepower and 23 lb-ft of torque translated into negligible improvement in our real-world acceleration testing.
Saddled with elephantine heft and eager to spin its rear all-season tires at launch, the Charger posted the same 4. At triple-digit speeds, the higher power on 93 octane gave the Charger an advantage measured in tenths of a second.
The Dodge also posted a 0. Just as important, the bellicose roar of the iron-block Hemi and the Charger's ability to reduce its rear tires to jungle-gym ground cover are unaffected by the fuel in the tank. While Ford's EcoBoost F stands out as an obvious exception, the Dodge Charger's numbers make for a tidy summary of our findings.
If you buy fuel with an octane rating above the manufacturer's requirement, you're likely to feel it in your wallet more than the seat of your pants.
How your engine constantly invites and silences engine knock to estimate a fuel's octane rating. Your car doesn't know the octane rating of the fuel in its tank. Instead, the engine controller calculates an inferred octane with closed-loop logic that continuously advances the ignition timing until it detects knock, which occurs when a portion of the fuel-air mixture ignites before the spark-plug-initiated flame front reaches it.
The further the computer can advance the timing without provoking knock, the higher the octane rating. During knock, the flame front travels through the combustion chamber up to 10 times quicker than the normal spark-initiated flame front. Left unchecked, these pressure waves can damage the head gasket, pistons, or cylinder head.
But the occasional brief knock is a useful tool for checking that the engine is operating efficiently. It's detected with one or more knock sensors bolted to the block to sense the oscillations created by the pressure waves with a typical frequency between 7 and 16 kilohertz. Stephen Russ, senior technical leader for gas engines at Ford, says this normal knock is usually detected and addressed within one or two combustion cycles and poses no threat to the engine.
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