What is the best gas for a car?

Answer 1

If your question refers to, "What is the best gasoline for your car?" your in luck. In a gasoline engine, the piston compresses a fuel and air mixture in the combustion chamber and is then ignited by the spark plug. This reaction of the gasoline/air mixture being burned forces the piston down which is connected to a connecting rod which in turn is connected to a crank. This turns the gasoline air mixture into rotating mechanical movement used to drive our vehicles.

Engines are built with a specific compression ratio in mind. This compression ratio is the volume in the cylinder when the piston is furthest in the down stroke, to the valume the piston compresses in the "quinch area". For instance, if you have a 50cc engine and the complete volume is 50cc, and your quinch area volume is 5cc with the piston top dead center, your compression ratio is 10:1.

Gasoline is rated in Octane. Standard gasoline at the pump is 85 octane and is good for engines with a compression ratio not to exceed 9.5:1. (This is an educated guess) Octane refers to the ability of the gasoline to be compressed without being ignited by the "heat of compression" Remember, the higher the compression, the more horsepower.

If you try to run a high compression engine like many motorcycle engines(11.5:1) on 85 Octane you may notice a pinging noise comming from it. This is the low octane fuel being preignited, and can actually cause damage to the piston and valves.

The best gasoline to run in your vehicle is the gas your owners manual tells you to run. Running premium or super unleaded in a vehicle that's compression is only 8.5:1 is pointless. Its no cleaner, it just cost more.

Alcohol or Methanol (Race fuel) has an ability to withstand high compression, but generally twice as much alcohol to gasoline is needed to go the same distance. You can certainly get a lot of horsepower out of these fuels but the draw back is having to use twice as much than gasoline. Same goes for Nitro Methanol.

In Drag race engines with a blower, the compression ratio is built to be right around 5:1. THis is so that when the engine is running, the blower can push tons of methanol or nitromethanol into the combusiton chamber essentially raising the compression ratio to 12:1 sometimes 16:1 only because of the amout of fuel and air the blower is forcing into the cylinders. This all results in HUGE HORSEPOWER.

Diesel is a fuel that has to be injected and is ignited by the "Heat of Compresstion" Generally diesel engines run 20:1 or higher compression ratios depending on the appliction.

So really, you have to answer your own question. What is my application? Only then will you know what the best gas to use is.