What type of gas?
02-05-2008, 02:05 PM
#26
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use 87 your car is not tuned for higher and if you use higher less is burned which clogs our crappy factory cat which is maybe why some of you dont have black gunk at tail end.Believe me its happened to me already when i used higher octane. I had to get a whole new dp but of course my dealership didnt charge me because of warranty and played it dumb pure and innocent. plz i warn you all use 87 octane unless you are tuned
Last edited by xpod666; 02-06-2008 at 07:54 AM.
02-05-2008, 02:10 PM
#27
I now use 93 octane after using 89 since i got my car. My reasoning:
After installing my GMPP sport exhaust and straight cut tip i noticed a build up of a black substance which im assuming is carbon inside of the tip and after i would wipe it off it would build up again after about a week. After running 93 octane this is no longer a buildup of black substance. I'm assuming this is because the fuel is burning cleaner and more efficiently. This may mean nothing or there may be something wrong with my engine =P who knows! PLEASE correct me if i'm wrong.
After installing my GMPP sport exhaust and straight cut tip i noticed a build up of a black substance which im assuming is carbon inside of the tip and after i would wipe it off it would build up again after about a week. After running 93 octane this is no longer a buildup of black substance. I'm assuming this is because the fuel is burning cleaner and more efficiently. This may mean nothing or there may be something wrong with my engine =P who knows! PLEASE correct me if i'm wrong.
running too high an octane hurts more than it helps. no reason for you to use anything other than 87 in your car.
02-05-2008, 02:18 PM
#28
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this is not true at all. you have a 2.2l, you should be using regular 87.
higher octane absolutely does not burn any cleaner. read up on octane and what it is, and what it's not. burning cleaner is one of the top octane myths of all time.
running too high an octane hurts more than it helps. no reason for you to use anything other than 87 in your car.
higher octane absolutely does not burn any cleaner. read up on octane and what it is, and what it's not. burning cleaner is one of the top octane myths of all time.
running too high an octane hurts more than it helps. no reason for you to use anything other than 87 in your car.
02-06-2008, 01:03 AM
#29
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well first---I have run both 91 and 87 in my 07 cobalt, and i've only noticed like 20miles difference in the use of either. There is that muffler thread showing tuned and untuned gains of like 1% HP and TQ between 87 and 91...don't know what thats about...gotta dig that up again.....
As for the science behind gas.....the more carbon-carbon bonds in your gas, the more energy thats made when they break. So if you live like me in Vegas, we have an oxygenized ~95% gas and 5% ethanol mix. Some places here have 90% gas and 10% ethanol, the octane rating may be the same all over the USA for 91 but the makeup of the gas can be different. The more gas and less ethanol you have, the more energy released in the explosion. All octane really is, is the resistance to premature detonation that causes knocking in your car. Now gas's optimum fuel:air ratio is 12.5:1. However the compression on your car also plays a big role, altitude, barometric pressure, and manifold vacuum all play into the account of how much air you (are able to) suck into your cylinder and how much the EFI pumps into it. if I was in somewhere below sea level - I would want to use 91 with our 10.0:1 compression ratios (my 2.2s), because you have a lot more air in your cylinders than us in vegas at 4800ft elevation.
Octane DOES produce performance difference when engines are running at peak power(tq) or under heavy loads. For example, the engine maximum power is reduced by about 4% with a fuel switch from 93 to 91 octane (11 hp, from 291 to 280 hp). If the engine is being run below maximum load, the difference in octane will have even less effect. Higher elevation means less octane is needed.
(courtesy of answers.com)
As for the science behind gas.....the more carbon-carbon bonds in your gas, the more energy thats made when they break. So if you live like me in Vegas, we have an oxygenized ~95% gas and 5% ethanol mix. Some places here have 90% gas and 10% ethanol, the octane rating may be the same all over the USA for 91 but the makeup of the gas can be different. The more gas and less ethanol you have, the more energy released in the explosion. All octane really is, is the resistance to premature detonation that causes knocking in your car. Now gas's optimum fuel:air ratio is 12.5:1. However the compression on your car also plays a big role, altitude, barometric pressure, and manifold vacuum all play into the account of how much air you (are able to) suck into your cylinder and how much the EFI pumps into it. if I was in somewhere below sea level - I would want to use 91 with our 10.0:1 compression ratios (my 2.2s), because you have a lot more air in your cylinders than us in vegas at 4800ft elevation.
Octane DOES produce performance difference when engines are running at peak power(tq) or under heavy loads. For example, the engine maximum power is reduced by about 4% with a fuel switch from 93 to 91 octane (11 hp, from 291 to 280 hp). If the engine is being run below maximum load, the difference in octane will have even less effect. Higher elevation means less octane is needed.
(courtesy of answers.com)
02-06-2008, 07:50 AM
#30
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well first---I have run both 91 and 87 in my 07 cobalt, and i've only noticed like 20miles difference in the use of either. There is that muffler thread showing tuned and untuned gains of like 1% HP and TQ between 87 and 91...don't know what thats about...gotta dig that up again.....
As for the science behind gas.....the more carbon-carbon bonds in your gas, the more energy thats made when they break. So if you live like me in Vegas, we have an oxygenized ~95% gas and 5% ethanol mix. Some places here have 90% gas and 10% ethanol, the octane rating may be the same all over the USA for 91 but the makeup of the gas can be different. The more gas and less ethanol you have, the more energy released in the explosion. All octane really is, is the resistance to premature detonation that causes knocking in your car. Now gas's optimum fuel:air ratio is 12.5:1. However the compression on your car also plays a big role, altitude, barometric pressure, and manifold vacuum all play into the account of how much air you (are able to) suck into your cylinder and how much the EFI pumps into it. if I was in somewhere below sea level - I would want to use 91 with our 10.0:1 compression ratios (my 2.2s), because you have a lot more air in your cylinders than us in vegas at 4800ft elevation.
Octane DOES produce performance difference when engines are running at peak power(tq) or under heavy loads. For example, the engine maximum power is reduced by about 4% with a fuel switch from 93 to 91 octane (11 hp, from 291 to 280 hp). If the engine is being run below maximum load, the difference in octane will have even less effect. Higher elevation means less octane is needed.
(courtesy of answers.com)
As for the science behind gas.....the more carbon-carbon bonds in your gas, the more energy thats made when they break. So if you live like me in Vegas, we have an oxygenized ~95% gas and 5% ethanol mix. Some places here have 90% gas and 10% ethanol, the octane rating may be the same all over the USA for 91 but the makeup of the gas can be different. The more gas and less ethanol you have, the more energy released in the explosion. All octane really is, is the resistance to premature detonation that causes knocking in your car. Now gas's optimum fuel:air ratio is 12.5:1. However the compression on your car also plays a big role, altitude, barometric pressure, and manifold vacuum all play into the account of how much air you (are able to) suck into your cylinder and how much the EFI pumps into it. if I was in somewhere below sea level - I would want to use 91 with our 10.0:1 compression ratios (my 2.2s), because you have a lot more air in your cylinders than us in vegas at 4800ft elevation.
Octane DOES produce performance difference when engines are running at peak power(tq) or under heavy loads. For example, the engine maximum power is reduced by about 4% with a fuel switch from 93 to 91 octane (11 hp, from 291 to 280 hp). If the engine is being run below maximum load, the difference in octane will have even less effect. Higher elevation means less octane is needed.
(courtesy of answers.com)
Last edited by xpod666; 02-06-2008 at 07:50 AM. Reason: Automerged Doublepost
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