Once crude oil is broken down into the smaller hydrocarbons, it is mixed with additives. Some additives are detergents to prevent buildup inside your engine, while others improve combustion, prevent corrosion, or allow easier cold starts in cold climates. Octane is one of those hydrocarbons in gasoline, and it increases the resistance of gasoline to detonate prematurely in your engine.
The higher the octane content in your fuel, the more resistant it is to predetonation that causes spark knock or pinging.
In some premium gasolines, there are increased levels of detergents and other additives, but the basis of premium gasoline is its octane rating. At the pump, regular gasoline is usually rated around 87 octane while premium is anywhere from 91 to 93 octane. One more thing about fuel composition - by and large, there is no difference in the energy contained in regular gasoline and premium gasoline.
That means that, aside from the resistance to predetonation, there is little difference in the fuel itself. As mentioned, premium gas prevents fuel predetonation under compression. To help clarify, think of it like a diesel engine. All the extra kinetic energy when the fuel is compressed causes it to explode and push the piston down in the cylinder.
In high-compression gasoline engines, the same principle occurs with regular gasoline. In high-compression engines, premium gas waits to ignite until the spark plug fires.
Knowing if you require premium gas is as easy as looking for a label behind your fuel door. Our certified mobile mechanics perform over services, including diagnostics, brakes, oil changes, scheduled mileage maintenances, and will come to you with all necessary parts and tools. We wanted to know. The dyno results shocked us. Not because of the hp difference between 91 and 93 octane. No, that delta was in line with expectations. Our jaws were left hanging by just how much power and torque we measured.
While BMW claims horsepower at the crank, the dyno reports it makes that much at the wheels after driveline losses on octane premium. And both fuels produced significantly more torque than BMW's advertised lb-ft. The higher-octane fuel trimmed a single tenth of a second across all of the M5's acceleration times.
That results in a time-bending 2. The BMW also claimed the largest fuel-economy margin in the test, but the 0. The M5 Competition stands as proof that the octane rating does make a difference, although in the case of these two premium fuels, if you're forced to use 91 octane, you're hardly missing out.
At Naturally then, the Ford hauls ass as effortlessly as it hauls a half-ton of manure. When fed 93 octane, this pound, self-propelled wheelbarrow will crash 60 mph in 5. Power at the wheels dropped from to horsepower with the change from 93 to 87 octane.
That difference seemed to grow, and we could even feel it from the driver's seat at the test track. Compared with premium fuel, regular feed sapped the F's urgency both leaving the line and in the meat of the tach sweep. 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. Of course modern engines can adjust for lower octanes with the penalty of reduced performance. In most cases higher octane does not improve MPG but does provide a little better performance. This can be important when towing, hot weather, or turbo engines that are more sensitive to octane requirements.
Owners manuals are the best place to see what is required and possibly recommended for your engine. I find I get higher miles per gallon when I use any gasoline that does not have ethanol in it.
When I use ethanol gasoline, my mileage drops into the 13 to 15 miles per gallon range. When using non-ethanol gasoline, my mileage goes up to the 23 to 27 mileage. What about 85 octane? Which is the best gas for ur car if a mechanic tell u u get the high percentage for ur car to help clean gas line out. I thought that octane was gasolines ability to hold oxygen therefore at higher elevations where the air is thinner the gasoline cannot hold as much oxygen resulting in a lower octane rating.
Is this correct? When your cars engine with carburetor is tuned for sea level driving, the gasoline octane rating should be determined on the compression ratio of the engines combustion chamber. The carbureted engine will start to smoke black smoke, too much fuel and start running erratically! Old hot rodders such as myself always carry a case with different sized main jets, and stop before the erratic behavior begins.
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