Living in humid conditions does have its benefits
Dense moisture in the air slightly cools the incoming charge. But it's also counterproductive, because the more moisture you have, the less room you have to efficiently burn fuel. For example if you have a 90F day in California with 20-percent humidity, your engine will demand a lot more octane in comparison to a 90F day in Florida with high humidity. The advantage of humidity is the moisture within the air helps to smooth out the combustion process. Minimal evaporative cooling enables the intake charge to maintain a slightly lower temperature, ultimately suppressing detonation and horsepower.
Altitude check for all you hermits living out there
For someone living in at a high altitude, fuel sold at the pump may decrease to 84- or 85- octane. Part of the ASTM gasoline regulations is any county 4,000 feet above sea level can reduce octane. Engines at higher elevations don't need the higher-octane levels when compared to vehicles at sea level. Fuel rules state that for every thousand feet above sea level, you are able to reduce the octane appetite by one number. Conceivably, if you filled your tank up in Denver and then loaded the car on a transport rig and towed it to sea level, the gas within the vehicle might detonate because of its lower octane.
What are the advantages of using a high-octane race gasoline?
Vehicles with a higher compression ratio, using nitrous or forced induction will typically need higher octane. With racing gasoline, consumers demand the best of the best in fuel quality, especially when paying a premium at the pumps. "When we blend our Rocket Brand Racing fuels, we don't use any of the real light stuff. We chop the tail end off and then go forward, picking the goodies out from the middle," says Wusz. The main reason for using a high-octane fuel is it will burn quickly in the engine-you can't afford to have a slow-burn gasoline when your engine is turning 9000 or 10000 rpm. With any slow-burning gasoline, the engine will likely push un-burned hydrocarbons out the pipe, which is considered unbeneficial. The main focus for any vehicle is to have as much burn in the combustion chamber as possible. This maximizes the conversion of chemical energy into mechanical energy; it ultimately takes all of the potential energy and makes as much of it into horsepower as mechanically possible.
Are gasoline companies cheating us out of quality fuel with their "supposed" octane numbers?
When a company puts out a 91-octane, unless there was some serious screw up, it's going to be anywhere in the range of 91.2 or 91.3-octane. "It should be at least a 91-octane unless someone drops some 87-octane in there. If they do that they're supposed to identify it and correct the problem. They may not, but they're supposed to," states Wusz. Just how accurate are these octane numbers that are posted at the gas station? "It's probably as accurate as a typical octane test engine," says Wusz.
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