regular, mid-grade or premium ?
07-15-2003, 03:59 AM
#21
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Hess runs 93 Octane around here for 1.56.She runs pretty damn smooth. My dad put in 87 one time....god did i try to burn that tank fast.
07-15-2003, 01:22 PM
#25
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My car has gotten to the point that I can actually tell the difference between 91 and 93 Octane. With a few mods, things change, and the octane requirement seems to go up. When I first had the car, before any mods, I could actually run 89 and not notice it......but did it rarely.
07-15-2003, 03:35 PM
#27
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General question: Do ALL cars run better with higher octane? Including economy cars. You would obviously think so, but I'm sure there is a better answer...there always is. 
07-15-2003, 04:14 PM
#28
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Not necessarily, the higher the octane, the slower it burns. The higher the compression, the more the tendency to "detonate" (burn too fast at the top of the power stroke). That is why we run high octane fuel in a high compression engine. It burns slower, throughout the power stroke.
Now assume you have a low compression vehicle, say a 7.5:1 compression, the lower octane will burn through the entire power stroke just fine, but if we use high octane (we will use 100 octane as an extreme example) in the same engine, the fuel will still be burning during the exhaust stroke, which is wasted engergy. Essentially, part of the combustion is taking place in your headers or exhaust manifolds. Now in our Bonnevilles, we have a computer to help regulate this. The O2 sensor will pick up a rich condition and the computer will lean out the mix. But the O2 sensor will be subject to a shortened life.
There are other variables (such as relative length of stroke--which usually contributes directly with the compression ratio, altitude and air density, etc), but this is the gist of it.
Now assume you have a low compression vehicle, say a 7.5:1 compression, the lower octane will burn through the entire power stroke just fine, but if we use high octane (we will use 100 octane as an extreme example) in the same engine, the fuel will still be burning during the exhaust stroke, which is wasted engergy. Essentially, part of the combustion is taking place in your headers or exhaust manifolds. Now in our Bonnevilles, we have a computer to help regulate this. The O2 sensor will pick up a rich condition and the computer will lean out the mix. But the O2 sensor will be subject to a shortened life.
There are other variables (such as relative length of stroke--which usually contributes directly with the compression ratio, altitude and air density, etc), but this is the gist of it.
07-15-2003, 09:04 PM
#29
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Originally Posted by dbtk2
My car has gotten to the point that I can actually tell the difference between 91 and 93 Octane. With a few mods, things change, and the octane requirement seems to go up. When I first had the car, before any mods, I could actually run 89 and not notice it......but did it rarely.
07-15-2003, 09:21 PM
#30
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We have 94 octane at Sunoco. Not sure what is offered in the US...wait Sunoco is in the US
http://www.sunoco.ca/content.asp?id=152
Thats the CDN site tho
http://www.sunoco.ca/content.asp?id=152
Thats the CDN site tho