87 Octane in Vette
Burning Brakes
Joined: Jan 2006
Posts: 900
Likes: 38
From: Waunakee Wisconsin
St. Jude Donor '20
So up to this point I have never used anything less then 93 in my 2000 C5, but recently I was talking to a buddy who claims he accidently put 87 in his C5 and it ran like a bat out of hell. He called another friend and was told that if the car is tuned for lower grade fuel that it will run better. He also said that if the car starts to make a pinging noise then to move up to 91 or 93. Any truth to this ? Thanks
I wish these posts regarding octane were banned for good. Read the owners manual, please. If you can't afford the gas, sell the car and buy a Prius. Sorry, but I think I'm ranting on behalf of many here.
Race Director
Joined: Apr 2007
Posts: 19,652
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From: Ideals are peaceful...History is violent...St.Charles, MO.
2020 Corvette of the Year Finalist (appearance mods)
C5 of Year Winner (appearance mods) 2019
St. Jude Donor '08-'09-'12 thru'22
So up to this point I have never used anything less then 93 in my 2000 C5, but recently I was talking to a buddy who claims he accidently put 87 in his C5 and it ran like a bat out of hell. He called another friend and was told that if the car is tuned for lower grade fuel that it will run better. He also said that if the car starts to make a pinging noise then to move up to 91 or 93. Any truth to this ? Thanks
Just my $.02 worth
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Le Mans Master
Joined: Aug 2004
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From: Southern New Jersey, The wet part at the bottom
St. Jude Donor '08-'09-'10
I would agree that 2 points wouldn't do any harm (pull timing), but where in New Jersey did you find 91 octane gas?
I use nothing but Shell V-Power, But I'm just curious, I've never seen it here.
I use nothing but Shell V-Power, But I'm just curious, I've never seen it here.
Racer
Joined: Apr 2004
Posts: 343
Likes: 167
From: Sugar Land Tx
I run quality (Chevron) 87 octane. Cars runs beautifully....I dont race it so I aint looking to be on "pinks" I get 31MPG on the highway, consistently. Picked the car up in Nebraska...drove it 900 miles with an avg MPG of 30MPG. 
Drifting
Joined: Dec 2004
Posts: 1,820
Likes: 2
From: San Diego
Using fuels of a lower octane than the vehicle was calibrated to will cause increased "Knock Sensor (KS)" system activity. This will result in a net decrease in spark advance and thus poorer fuel economy. Using fuel of a higher octane than the vehicle was calibrated for will not increase fuel econ
Source: http://autorepair.about.com/cs/gener...a022501a_2.htm
Source: http://autorepair.about.com/cs/gener...a022501a_2.htm
Assuming your source is correct (there is a loss of about 1mpg when substituting 87 for 91) and the difference between 87 and 91 octane is 20-cents; you will save money using premium (between 12-cents to $1.86 per full tank) if your corvette averages between 15 and 22mpg on a full tank of gas.
If you average between 23mpg and 34mpg over a full tank, it will be more cost effective (from 04-cents to $1.12 per full tank) to purchase 87 octane.
If the spread is 30-cents or more between 87 and 91 then you'll save money buying 87 no matter what your average mileage is between 15 and 34.
As can be seen, unless you consistently get over 23mpg it is NOT worth it to use 87 octane in the hope you will "save money."
So, you guys using 87 and getting less than 23mpg per full fillup are really losing two ways, 1) worse performance, 2) its costing you more money!
..rickko..
Last edited by rickko; Jun 11, 2008 at 09:17 PM.
Burning Brakes
Joined: Aug 2005
Posts: 845
Likes: 0
From: Mesa Arizona
At the risk of "stealing" this thread, has anyone considered that if we were able burn straight ethanol (E100?) the octane levels would be in the 97 - 98 range. This in turn would allow compression ratios in the 11.5:1 - 12:1 range. At those levels, wouldn't we get equal or better performance, fewer emissions, and pay less money to OPEC?
Anyone with any information along these lines?
Glen
Anyone with any information along these lines?
Glen
Tech Contributor
Joined: Dec 2003
Posts: 19,384
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From: Horncastle Lincolnshire, England
2023 C5 of the Year Finalist - Unmodified
Racer
Joined: Jul 2007
Posts: 469
Likes: 0
From: Salt Lake City Utah
Why lessen the perfromance of a sports car! Isn't the reason you bought it was for the power? You should have gotten a late 70's C-3 with only 180HP then. Don't tell me you bought it only for the looks.
Speed is one ingredient of testosterone!
Speed is one ingredient of testosterone!
Race Director
Joined: Jan 2006
Posts: 10,554
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From: Not on either liberal coast.
Team Owner
Joined: Mar 2001
Posts: 21,325
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From: small town in S.E Pa. PA
St. Jude Donor '03-'04
2nd generation owners of this car make me cry
This just goes to prove anyone can own a Corvette... 87 Octane is "NOT" recommended to be used in this car... the manual only states that you can use it.. what it doesn't say and should say is it can be used to get you a station that does have 91 octane or better. Meaning a half tank wont hurt the car, but running it constantly is a no no... We put that idiot proof sticker on the door for tire pressure only as a product liability disclaimer ( 30 psi cold ) because people were actually pumping their F1's up to Max tire pressure found on the sidewall... the only thing I see with threads like this is there is a New breed of Corvette owner out there. To say your car runs fine on 87 octane is laughable.. stock cars in high altitude or extreme hot weather have problems with 91 octane ... 87 octane will retard timing causing a 10 to 20 % drop in HP depending on the amount of timing pulled.. even going up a slight incline will cause this.. and load on the motor can cause detonation without proper octane.. I dont even know why I am posting in this thread, I guess its a sad epitaph of what has become of the car I invested 5 years of my life too. When this car was new it was like a new million dollar housing community.. its sad to see that community has turned into a ghetto.
Last edited by Evil-Twin; Jun 12, 2008 at 04:53 PM.
Race Director
Joined: Jan 2006
Posts: 10,554
Likes: 33
From: Not on either liberal coast.
Bill, it gets asked on every car forum...just like "Is it ok to use premium when the manufacturer says to use regular?' 'How much horsepower will I get if I do?"
It's the internet...it's the way it'll always be.
But, I repeat, it's the owners car to do with as the owner pleases! Most won't have the car very long anyway...fads change...
It's the internet...it's the way it'll always be.
But, I repeat, it's the owners car to do with as the owner pleases! Most won't have the car very long anyway...fads change...
Last edited by hotwheels57; Jun 12, 2008 at 04:53 PM.