Running premium in a regular car-don't
06-30-2007, 04:07 PM
#1
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Running premium in a regular car-don't
Run your car on the recomended fuel stated in the owners manual. Otherwise, you're wasting your money, and ACTUALLY mucking-up your engine.
Your compression ratio is what determines the octane rating that your car requires to run CLEANLY AND EFFICIENTLY. Putting high-test in an 89 octane car produces incomplete combustion with every power stroke of the engine. Your PCM/ECM will then try to compensate, but it can't. It can only make corrections when concerning lower octane fuel.
Octane is another word for flashpoint. Thats it. It has no inherent performance gaining properties (in any way). It has additives that force it to detonate at a higher temperature, wich is required in boosted/ ultra high compression engines.
Example: A 12:1 compresion ratio produces pressures 30% higher than 9:1. When a fuel/air mixture is compressed, it produces HEAT.....alot of it, and it increases exponentially. In other words, the difference in the charge temperature is much more than 30% in the above mentioned comparison. At 12:1 temperatures, 89 octane fuel would detonate before the piston arrived at its home (top dead center) before the spark plug even fired. This destroys the piston,wristpins, crank and con-rods in short order.
Conversley, at a 9:1 ratio there is insufficient heat created by the compression process to allow higher octane fuels to combust completely when the spark fires.........it just farts, leaves residue behind (gumming-up valvetrain components), creates an inefficient process that actually reduces your power. 94 octane contains no more energy than 89 per volume.
For many on this site it's a no-brainer, but for others it's something they didn't know. With gas prices as they are, it will make a huge diffence over a lifetime of driving your car.
Your compression ratio is what determines the octane rating that your car requires to run CLEANLY AND EFFICIENTLY. Putting high-test in an 89 octane car produces incomplete combustion with every power stroke of the engine. Your PCM/ECM will then try to compensate, but it can't. It can only make corrections when concerning lower octane fuel.
Octane is another word for flashpoint. Thats it. It has no inherent performance gaining properties (in any way). It has additives that force it to detonate at a higher temperature, wich is required in boosted/ ultra high compression engines.
Example: A 12:1 compresion ratio produces pressures 30% higher than 9:1. When a fuel/air mixture is compressed, it produces HEAT.....alot of it, and it increases exponentially. In other words, the difference in the charge temperature is much more than 30% in the above mentioned comparison. At 12:1 temperatures, 89 octane fuel would detonate before the piston arrived at its home (top dead center) before the spark plug even fired. This destroys the piston,wristpins, crank and con-rods in short order.
Conversley, at a 9:1 ratio there is insufficient heat created by the compression process to allow higher octane fuels to combust completely when the spark fires.........it just farts, leaves residue behind (gumming-up valvetrain components), creates an inefficient process that actually reduces your power. 94 octane contains no more energy than 89 per volume.
For many on this site it's a no-brainer, but for others it's something they didn't know. With gas prices as they are, it will make a huge diffence over a lifetime of driving your car.
06-30-2007, 04:27 PM
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Makes perfect sense... I knew that higher octane had no real HP effect, so to speak...but I knew it had a significance for specific engines. Good info... +1
07-01-2007, 05:38 AM
#4
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yupp 93 is just harder to burn than 87. actually if you get right down to it 87 octane contains more btu's than 93 so in theory if you could stop detonation you could make more power with 87 octane
07-01-2007, 06:01 AM
#5
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http://en.wikipedia.org/wiki/Octane_rating
"Octane rating has no direct impact on the deflagration (burn) of the air/fuel mixture in the combustion chamber. Other properties of gasoline and engine design account for the manner at which deflagration takes place. In other words, the flame speed of a normally ignited mixture is not directly connected to octane rating. Deflagration is the type of combustion that constitues the normal burn. Detonation is a different type of combustion and this is to be avoided in spark ignited gasoline engines. Octane rating is a measure of detonation resistance, not deflagration characteristics."
07-01-2007, 06:18 AM
#6
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Actually, that is incorrect and a misconception...
http://en.wikipedia.org/wiki/Octane_rating
"Octane rating has no direct impact on the deflagration (burn) of the air/fuel mixture in the combustion chamber. Other properties of gasoline and engine design account for the manner at which deflagration takes place. In other words, the flame speed of a normally ignited mixture is not directly connected to octane rating. Deflagration is the type of combustion that constitues the normal burn. Detonation is a different type of combustion and this is to be avoided in spark ignited gasoline engines. Octane rating is a measure of detonation resistance, not deflagration characteristics."
http://en.wikipedia.org/wiki/Octane_rating
"Octane rating has no direct impact on the deflagration (burn) of the air/fuel mixture in the combustion chamber. Other properties of gasoline and engine design account for the manner at which deflagration takes place. In other words, the flame speed of a normally ignited mixture is not directly connected to octane rating. Deflagration is the type of combustion that constitues the normal burn. Detonation is a different type of combustion and this is to be avoided in spark ignited gasoline engines. Octane rating is a measure of detonation resistance, not deflagration characteristics."
07-01-2007, 06:25 AM
#7
Senior Member
I'm not perfect or a know it all like some people think
I got your back Ozzy.
07-01-2007, 08:15 AM
#10
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07-01-2007, 10:29 AM
#11
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07-01-2007, 08:16 PM
#13
Senior Member
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