HIGH OCTANE FUELS

[voodoo22]

Originally Posted by jambo101

I never did understand why people buy a cheap reliable economy car then spend $0.20 more per gallon to put in premium fuel on the mistaken assumption that its going to make the car go faster and get better mileage.If you wanted a faster car buying a Yaris is a poor choice.
PS,your premium gas may only be 4% higher than regular but over the life of the car that will amount to some serious unnecessarily spent money.

Like when my brother bought a $55k BMW and put in regular. What a tard.

[jambo101]

Originally Posted by voodoo22

Like when my brother bought a $55k BMW and put in regular. What a tard.

My father in law had this strange habit of filling his pickup truck with the cheapest oil he could find usually the $0.75 a quart stuff and fill up his gas tank with the most expensive gas he could find.

[Marthos]

Octane is a rating, of a fuels ability to combust.

The higher the octane rating the harder it is to "burn" that fuel.

The higher the compression, the higher the octane needed.

When a low octane fuel is compressed to high it will self combust, causing preignition, that is when the fuel burns before the spark plug fires and the piston is on the downward power stroke.

A supercharged engine needs high octane fuel so the compression does not ingnite the fuel before the spark plug fires.

Always use the recomended fuel octane rating listed in the owners manual.

Only go up to a higher octane if you hear Pinging, as this can lead to major engine damage.

[Yaris Hilton]

Higher octane doesn't mean it's harder to burn, just that it's slower to autoignite when heated to a temperature where that can occur.

Preignition is different from detonation in that detonation occurs after the spark has fired, in the part of the fuel/air mixture that hasn't yet been reached by the expanding flame front from the spark. Preignition is caused by hot spots in the chamber igniting the fuel before the spark fires. High octane won't fix that.

[Marthos]

Originally Posted by Yaris Hilton

Higher octane doesn't mean it's harder to burn, just that it's slower to autoignite when heated to a temperature where that can occur.

Preignition is different from detonation in that detonation occurs after the spark has fired, in the part of the fuel/air mixture that hasn't yet been reached by the expanding flame front from the spark. Preignition is caused by hot spots in the chamber igniting the fuel before the spark fires. High octane won't fix that.

Its just the way it was explained to me years ago in Auto Tech.
laymens terms was what i was going for.

This is from a wiki

"The octane rating is a measure of the resistance of gasoline and other fuels to detonation (engine knocking) in spark-ignition internal combustion engines."


Changed that to preignition.

[Yaris Hilton]

Usually when you hear pinging, you're hearing detonation. If it's preignition, something's wrong with the engine that needs fixing fast.