Gas!
Le Mans Master
Joined: Dec 2003
Posts: 9,713
Likes: 0
From: East Las Vegas Nv
100 oct. here 4.95 gal and shes worth it @ 26 mpg . i drive mine daily. if you love your car give her the best you cant go wrong. they will run on 87 but think about realy how much your saving. im pretty sure you will see most people putting the 91 or more. if not you saving what a buck. there will be more people leaving replys
Burning Brakes
Joined: Oct 2001
Posts: 1,146
Likes: 0
From: The Internet
Unless this is a trick question, the answer is "the lowest octane rating that doesn't cause knock"
Using a higher octane rating than you need is just plain silly because, despite what people would like to believe, higher octane fuels do not produce more power and, in fact, may cause worse performance in and of themselves.
You'll hear all manner of rationalisations for the emotional case of using the most expensive; it's only a few pennies, it's a 50K sports car, my baby deserves the "good stuff" versus the "bad stuff", but the real answer lies in understanding how an internal combustion engine works and what an octane rating is all about.
Using a higher octane rating than you need is just plain silly because, despite what people would like to believe, higher octane fuels do not produce more power and, in fact, may cause worse performance in and of themselves.
You'll hear all manner of rationalisations for the emotional case of using the most expensive; it's only a few pennies, it's a 50K sports car, my baby deserves the "good stuff" versus the "bad stuff", but the real answer lies in understanding how an internal combustion engine works and what an octane rating is all about.
Race Director
Joined: Nov 2003
Posts: 12,346
Likes: 5
From: Mustang OK
From the C5 Owner's Manual:
The only reason that you should need to go to a higher octane than 91 for the stock LS1/LS6 engine is if your getting some detonation (engine knock). Even then, you might want to consider trying a different brand of gasoline first. As mentioned above, there is a lot of misunderstanding of what octane is and does and octane in itself does not increase horsepower.
Gasoline Octane
Use premium unleaded gasoline with a posted octane of 91 or higher for best performance. You may also use middle grade or regular unleaded gasoline rated at 87 octane or higher, but your vehicle’s acceleration may be slightly reduced. If the engine octane is less than 87, you may get a heavy knocking noise when you drive. If this occurs, use a gasoline rated at 87 octane or higher as soon as possible. Otherwise, you might damage your engine.
Use premium unleaded gasoline with a posted octane of 91 or higher for best performance. You may also use middle grade or regular unleaded gasoline rated at 87 octane or higher, but your vehicle’s acceleration may be slightly reduced. If the engine octane is less than 87, you may get a heavy knocking noise when you drive. If this occurs, use a gasoline rated at 87 octane or higher as soon as possible. Otherwise, you might damage your engine.
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Le Mans Master
Joined: Jun 2004
Posts: 6,269
Likes: 50
From: Dallas Texas
St. Jude Donor '06-'07-'09-'10
Originally Posted by chocoholic
Unless this is a trick question, the answer is "the lowest octane rating that doesn't cause knock"
Using a higher octane rating than you need is just plain silly because, despite what people would like to believe, higher octane fuels do not produce more power and, in fact, may cause worse performance in and of themselves.
You'll hear all manner of rationalisations for the emotional case of using the most expensive; it's only a few pennies, it's a 50K sports car, my baby deserves the "good stuff" versus the "bad stuff", but the real answer lies in understanding how an internal combustion engine works and what an octane rating is all about.
Using a higher octane rating than you need is just plain silly because, despite what people would like to believe, higher octane fuels do not produce more power and, in fact, may cause worse performance in and of themselves.
You'll hear all manner of rationalisations for the emotional case of using the most expensive; it's only a few pennies, it's a 50K sports car, my baby deserves the "good stuff" versus the "bad stuff", but the real answer lies in understanding how an internal combustion engine works and what an octane rating is all about.
and a Tier 1 gasoline that has Techron is perferable. A higher octane number means that the flame spread rate of the fuel upon ignition is slower thereby retarding knock. Using a fuel with a higher rating than necessary will actually reduce performance slightly. The oil companies have done a good marketing job on the public about using Premium Gas. 
Melting Slicks
Joined: Jan 2004
Posts: 3,012
Likes: 15
From: Jensen Beach FL
Originally Posted by chocoholic
Unless this is a trick question, the answer is "the lowest octane rating that doesn't cause knock"
Using a higher octane rating than you need is just plain silly because, despite what people would like to believe, higher octane fuels do not produce more power and, in fact, may cause worse performance in and of themselves.
You'll hear all manner of rationalisations for the emotional case of using the most expensive; it's only a few pennies, it's a 50K sports car, my baby deserves the "good stuff" versus the "bad stuff", but the real answer lies in understanding how an internal combustion engine works and what an octane rating is all about.
Using a higher octane rating than you need is just plain silly because, despite what people would like to believe, higher octane fuels do not produce more power and, in fact, may cause worse performance in and of themselves.
You'll hear all manner of rationalisations for the emotional case of using the most expensive; it's only a few pennies, it's a 50K sports car, my baby deserves the "good stuff" versus the "bad stuff", but the real answer lies in understanding how an internal combustion engine works and what an octane rating is all about.
Le Mans Master
Joined: Mar 2005
Posts: 5,492
Likes: 39
From: Tampa Florida
you are suppose to use the least octane possible that doesnt get knock, so no putting in higher octane like 100 will do nothing but probably actually hurt your performance, thats why when i had a supra it ran okay at 93, like a beast at 100, and ok at 116
i use 93 personally
i use 93 personally
Team Owner
Joined: May 2005
Posts: 23,682
Likes: 9
From: Flagstaff Az.
Gas
I agree with Craig. You can run 87 but the car cannot perform at the same level as if you were running a higher octane number. The computor will retard the spark at higher throttle or pulling under load so as to stop detonation.
Instructor
Joined: Aug 2005
Posts: 233
Likes: 0
Originally Posted by GrayC5
From the C5 Owner's Manual:
The only reason that you should need to go to a higher octane than 91 for the stock LS1/LS6 engine is if your getting some detonation (engine knock). Even then, you might want to consider trying a different brand of gasoline first. As mentioned above, there is a lot of misunderstanding of what octane is and does and octane in itself does not increase horsepower.
The only reason that you should need to go to a higher octane than 91 for the stock LS1/LS6 engine is if your getting some detonation (engine knock). Even then, you might want to consider trying a different brand of gasoline first. As mentioned above, there is a lot of misunderstanding of what octane is and does and octane in itself does not increase horsepower.
Instructor
Joined: Feb 2004
Posts: 171
Likes: 19
From: Marietta GA
Try this post: http://forums.corvetteforum.com/show...8&page=1&pp=20
I'll sum it up for you: you can use the LOWEST octane that doesn't cause PINGING (detonation), but it may cause a slight drop in performance. Higher compression engines need higher octane, but how high (or low)? 87? 89? 91? You just have to try it to find out. Higher octane does not mean more "power". It is a "detonation" rating. ALTHOUGH: "your knock sensor can compensate for low octane fuel by retarding the spark, at a cost in performance. But the reverse is not true. Once octane is high enough to allow optimum spark advance, more octane doesn’t help, because greater than optimum spark advance does not increase performance." So how do you know if you are still acheiving maximum spark advance using the lowest octane? Hell if I know.
At least that's what I got after reading that post. Please correct me if I'm wrong.
I'll sum it up for you: you can use the LOWEST octane that doesn't cause PINGING (detonation), but it may cause a slight drop in performance. Higher compression engines need higher octane, but how high (or low)? 87? 89? 91? You just have to try it to find out. Higher octane does not mean more "power". It is a "detonation" rating. ALTHOUGH: "your knock sensor can compensate for low octane fuel by retarding the spark, at a cost in performance. But the reverse is not true. Once octane is high enough to allow optimum spark advance, more octane doesn’t help, because greater than optimum spark advance does not increase performance." So how do you know if you are still acheiving maximum spark advance using the lowest octane? Hell if I know.
At least that's what I got after reading that post. Please correct me if I'm wrong.
Race Director
Joined: Nov 2003
Posts: 12,346
Likes: 5
From: Mustang OK
Originally Posted by allaboutdaz
is this what is says on the manual??
Last edited by GrayC5; Sep 1, 2005 at 04:21 PM.
Burning Brakes
Joined: Oct 2001
Posts: 1,146
Likes: 0
From: The Internet
Tyler has hit the nail on the head.
For some reason, people associate octane with horsepower but that relationship does not exist. The number of BTUs in a given fuel is not predicated upon its octane rating octane. Hence, higher octane fuel has no capacity to produce more power than lower octane fuel.
However, a particular higher-compression engine may need a higher octane fuel for it to produce maximum power compared to another but, again, if you overdo it you run the risk of incomplete combustion and you lose power.
So, again, you use the octane rating that allows your engine to produce peak power. Stuffing in 100 octane fuel to an engine that only needs 91, wastes money and power.
For some reason, people associate octane with horsepower but that relationship does not exist. The number of BTUs in a given fuel is not predicated upon its octane rating octane. Hence, higher octane fuel has no capacity to produce more power than lower octane fuel.
However, a particular higher-compression engine may need a higher octane fuel for it to produce maximum power compared to another but, again, if you overdo it you run the risk of incomplete combustion and you lose power.
So, again, you use the octane rating that allows your engine to produce peak power. Stuffing in 100 octane fuel to an engine that only needs 91, wastes money and power.
Melting Slicks
Joined: Jan 2004
Posts: 3,012
Likes: 15
From: Jensen Beach FL
Originally Posted by Tyler Dirden
Try this post: http://forums.corvetteforum.com/show...8&page=1&pp=20
I'll sum it up for you: you can use the LOWEST octane that doesn't cause PINGING (detonation), but it may cause a slight drop in performance. Higher compression engines need higher octane, but how high (or low)? 87? 89? 91? You just have to try it to find out. Higher octane does not mean more "power". It is a "detonation" rating. ALTHOUGH: "your knock sensor can compensate for low octane fuel by retarding the spark, at a cost in performance. But the reverse is not true. Once octane is high enough to allow optimum spark advance, more octane doesn’t help, because greater than optimum spark advance does not increase performance." So how do you know if you are still acheiving maximum spark advance using the lowest octane? Hell if I know.
At least that's what I got after reading that post. Please correct me if I'm wrong.
I'll sum it up for you: you can use the LOWEST octane that doesn't cause PINGING (detonation), but it may cause a slight drop in performance. Higher compression engines need higher octane, but how high (or low)? 87? 89? 91? You just have to try it to find out. Higher octane does not mean more "power". It is a "detonation" rating. ALTHOUGH: "your knock sensor can compensate for low octane fuel by retarding the spark, at a cost in performance. But the reverse is not true. Once octane is high enough to allow optimum spark advance, more octane doesn’t help, because greater than optimum spark advance does not increase performance." So how do you know if you are still acheiving maximum spark advance using the lowest octane? Hell if I know.
At least that's what I got after reading that post. Please correct me if I'm wrong.
Le Mans Master
Joined: Jun 2004
Posts: 6,269
Likes: 50
From: Dallas Texas
St. Jude Donor '06-'07-'09-'10
Originally Posted by chocoholic
Tyler has hit the nail on the head.
For some reason, people associate octane with horsepower but that relationship does not exist. The number of BTUs in a given fuel is not predicated upon its octane rating octane. Hence, higher octane fuel has no capacity to produce more power than lower octane fuel.
However, a particular higher-compression engine may need a higher octane fuel for it to produce maximum power compared to another but, again, if you overdo it you run the risk of incomplete combustion and you lose power.
So, again, you use the octane rating that allows your engine to produce peak power. Stuffing in 100 octane fuel to an engine that only needs 91, wastes money and power.
For some reason, people associate octane with horsepower but that relationship does not exist. The number of BTUs in a given fuel is not predicated upon its octane rating octane. Hence, higher octane fuel has no capacity to produce more power than lower octane fuel.
However, a particular higher-compression engine may need a higher octane fuel for it to produce maximum power compared to another but, again, if you overdo it you run the risk of incomplete combustion and you lose power.
So, again, you use the octane rating that allows your engine to produce peak power. Stuffing in 100 octane fuel to an engine that only needs 91, wastes money and power.
Years ago when 130 octane Avgas was availible, I knew a Guy who thought it would be great in his car. It didn't take long before his exhaust valves were burnt as the Avgas was still burning as it was exiting. The Avgas worked fine in a low rpm aircraft engine, but not in a car. Tetraethyl lead was added to slow the flame front at ignition and reduce detonation. The more lead the high the octane rating and the slower the gas burned.
Race Director
Joined: Apr 2001
Posts: 19,329
Likes: 16
From: Saint Augustine, FL
Mid-TN Events Coordinator
St. Jude Donor '03-'04-'05-'06-'07-'08-'09-'10-'11-'12-'13-'14-'15-'16
Originally Posted by Smoke-N-Shot
I don't put many miles on my vette but wouldn't consider anything but 92 or better.....