Octane questions......
#14
03-06-2010, 01:01 PM
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Um, it doesn't sound like you have a grasp of what octane is.
Octane is an additive put in gasoline to resist detonation. It changes how the gasoline reacts to heat and pressure. If you have an engine designed to run on 87 octane, it is a low compression motor with late ignition. The 87 burns easier because of the lower octane rating, so it burns faster. If you have an engine designed to run on high octane, it is a high compression motor and/or an advanced timed motor where the spark occurs further from TDC. If you have low octane gas in either situation, it will burn too fast and spark knock, so you need the higher octane to slow down the detonation. The added power does not come from the gasoline itself, but from the increased heat and pressure by igniting the gas earlier (in an advanced timed motor) or compressing it more (in a high compression motor).
If you run 93 octane in an engine designed to run on 87, the gas will burn colder and slower, and you will have increased emissions, increased carbon buildup, and decreased power. If you continue to do so for a long period of time, it will eventually lead to bad build-up problems in the heads and upper cylinders. So you are absolutely not correct in saying you are ok to use 93 in an engine designed to run 87.
Octane is an additive put in gasoline to resist detonation. It changes how the gasoline reacts to heat and pressure. If you have an engine designed to run on 87 octane, it is a low compression motor with late ignition. The 87 burns easier because of the lower octane rating, so it burns faster. If you have an engine designed to run on high octane, it is a high compression motor and/or an advanced timed motor where the spark occurs further from TDC. If you have low octane gas in either situation, it will burn too fast and spark knock, so you need the higher octane to slow down the detonation. The added power does not come from the gasoline itself, but from the increased heat and pressure by igniting the gas earlier (in an advanced timed motor) or compressing it more (in a high compression motor).
If you run 93 octane in an engine designed to run on 87, the gas will burn colder and slower, and you will have increased emissions, increased carbon buildup, and decreased power. If you continue to do so for a long period of time, it will eventually lead to bad build-up problems in the heads and upper cylinders. So you are absolutely not correct in saying you are ok to use 93 in an engine designed to run 87.
Last edited by DCypherThis13; 03-06-2010 at 01:06 PM.
#15
03-06-2010, 06:58 PM
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the higher the octane the cleaner the gas( thats why it's more expensive, more refining ), the cleaner the gas the more volatile it is, the more likely you will have pre-ignition in a carbon filled engine. don't know much about octane boosters but it seems like adding something like a 98 octane bottle to bring your gas up a few notches.
#16
03-06-2010, 11:09 PM
OK, Mr. Wizard, I think what your trying to tell me is I've got a timing issue. I know that I have a mild vacuum leak, but that would only delay ignition(as I recall), meaning that the truck would run worse the higher the octane rating. But the opposite is true. Gutless on regular, ate-your-Camaro-for-breakfast-and-had-room-for-seconds on premium. The engine will miss and sputter at idle, unless I run high octane fuel. That also doesn't tell me why it ran so well right after I got it. The vacuum leak has been there for about 2 months now. I've had the truck for over a year. And I started running premium about 2 months after I got it.
Also, your statement about the vacuum leak is not necessarily true. As you open the throttle up, manifold vacuum decreases. So if you have a vacuum leak bleeding off the manifold vacuum, the MAP sensor is going to get bad readings and the computer could think you are trying to accelerate harder than you are. The computer advances the timing the harder you are accelerating, so you could very well be running an advanced timing table with that vacuum leak. I don't know how likely that is... its hard to tell what the computer is thinking... but it is possible.
#17
03-07-2010, 02:21 AM
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the higher the octane the cleaner the gas( thats why it's more expensive, more refining ), the cleaner the gas the more volatile it is, the more likely you will have pre-ignition in a carbon filled engine. don't know much about octane boosters but it seems like adding something like a 98 octane bottle to bring your gas up a few notches.
#18
03-07-2010, 02:47 AM
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#19
03-07-2010, 03:00 AM