Octane ratings vs power
Pro
Joined: Jul 2007
Posts: 535
Likes: 1
From: San Diego CA
Th car is a 50-state car, meaning that Chevrolet did not produce California-only models, but rather made one car that was emissions compliant in all 50 states. The highest octane available at the gas pump in California and other Western states is 91 Octane [(Research Octane+Motor Octane)/2 or R+M/2 or Anti-Knock Index]. In other states it can be as high as 94 Octane R+M/2. That's why the owner's manual states that 91 octane is recommended. The engine will run on 87 octane, but as stated in earlier posts, it will exhibit Knock under heavy loads. That is also why Chevrolet designed the Powertrain Control Module (PCM) with 2 Spark Timing tables: a High Octane table & a Low Octane table. This is so that in the event of low octane fuel in the car, the PCM will detect the Knock via the Knock Sensors and switch to the Low Octane Spark Timing table.
With that said, 91 Octane is the lowest that you should run in your Corvette, and if higher octane fuel is available, up to 94 octane may be used to eliminate the chance of engine knock under heavy loads.
Here's a link to a wikipedia article on gasoline octane, and it notes the differences in regional blends of gasoline.
http://en.wikipedia.org/wiki/Octane_rating
With that said, 91 Octane is the lowest that you should run in your Corvette, and if higher octane fuel is available, up to 94 octane may be used to eliminate the chance of engine knock under heavy loads.
Here's a link to a wikipedia article on gasoline octane, and it notes the differences in regional blends of gasoline.
http://en.wikipedia.org/wiki/Octane_rating
Last edited by c5_4_me; Jan 14, 2010 at 06:38 PM. Reason: wikipedia
Instructor
Joined: Dec 2009
Posts: 236
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Le Mans Master
Joined: Feb 2003
Posts: 6,683
Likes: 144
From: Memphis Tennessee
Here's an interesting twist.
One of my best friends lab tests octane and cetane for Valero refinery here in MEM. He very often tells me that as they "cook" the gas, most times it well exceedes the posted octane rating on the pump. Just a few weeks ago, he told me that that particular day's gas was all 94 octane....all of it, and that they did not produce any "premium" as the volume produced was sufficient for both grades.
Now, I would not chance it, but I think it is interesting that the labeled rating may be exceeded. Makes you wonder about one place with 91 and another with 93.
Bottom line for me, get the good stuff and don't worry about it.
One of my best friends lab tests octane and cetane for Valero refinery here in MEM. He very often tells me that as they "cook" the gas, most times it well exceedes the posted octane rating on the pump. Just a few weeks ago, he told me that that particular day's gas was all 94 octane....all of it, and that they did not produce any "premium" as the volume produced was sufficient for both grades.
Now, I would not chance it, but I think it is interesting that the labeled rating may be exceeded. Makes you wonder about one place with 91 and another with 93.
Bottom line for me, get the good stuff and don't worry about it.
Thread Starter
Heel & Toe
Joined: Jan 2010
Posts: 18
Likes: 0
From: Norfolk
Shell Vpower 99RON $7.14 a gallon (£4.46)
Normal 95RON is about $6.72 a gallon (£4.20)
When I picked my car up it was on reserve, I filled it with 95RON and it cost £72.00 ($45)
What are the fuel prices in the US at the moment? Just thought I'd throw this in to depress me for the weekend lol
Tech Contributor
Joined: Dec 2003
Posts: 19,384
Likes: 87
From: Horncastle Lincolnshire, England
2023 C5 of the Year Finalist - Unmodified
In the Uk typically fuel is costing:
Shell Vpower 99RON $7.14 a gallon (£4.46)
Normal 95RON is about $6.72 a gallon (£4.20)
When I picked my car up it was on reserve, I filled it with 95RON and it cost £72.00 ($45)
What are the fuel prices in the US at the moment? Just thought I'd throw this in to depress me for the weekend lol
Shell Vpower 99RON $7.14 a gallon (£4.46)
Normal 95RON is about $6.72 a gallon (£4.20)
When I picked my car up it was on reserve, I filled it with 95RON and it cost £72.00 ($45)
What are the fuel prices in the US at the moment? Just thought I'd throw this in to depress me for the weekend lol
I paid £1.19 a litre last week
BTW £72 is $119 or was it £45?
Last edited by DeeGee; Jan 15, 2010 at 03:05 AM.
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Pro
Joined: Jul 2007
Posts: 535
Likes: 1
From: San Diego CA
In the Uk typically fuel is costing:
Shell Vpower 99RON $7.14 a gallon (£4.46)
Normal 95RON is about $6.72 a gallon (£4.20)
When I picked my car up it was on reserve, I filled it with 95RON and it cost £72.00 ($45)
What are the fuel prices in the US at the moment? Just thought I'd throw this in to depress me for the weekend lol
Shell Vpower 99RON $7.14 a gallon (£4.46)
Normal 95RON is about $6.72 a gallon (£4.20)
When I picked my car up it was on reserve, I filled it with 95RON and it cost £72.00 ($45)
What are the fuel prices in the US at the moment? Just thought I'd throw this in to depress me for the weekend lol
Sorry it depresses you that it is so expensive there. But thanks for sharing, because even though I am in California, with the most expensive gas in the US, it is costing me less than half as much as you! ($3.35 for 91 AKI at last fill-up on Monday 1/11/10)
On a side note, can you get E85 ethanol there?
Last edited by c5_4_me; Jan 15, 2010 at 02:07 PM. Reason: added my cost
Melting Slicks
Joined: Apr 2009
Posts: 2,479
Likes: 36
Thread Starter
Heel & Toe
Joined: Jan 2010
Posts: 18
Likes: 0
From: Norfolk
JEEBUS! THAT IS EXPENSIVE!
Sorry it depresses you that it is so expensive there. But thanks for sharing, because even though I am in California, with the most expensive gas in the US, it is costing me less than half as much as you! ($3.35 for 91 AKI at last fill-up on Monday 1/11/10)
On a side note, can you get E85 ethanol there?
Sorry it depresses you that it is so expensive there. But thanks for sharing, because even though I am in California, with the most expensive gas in the US, it is costing me less than half as much as you! ($3.35 for 91 AKI at last fill-up on Monday 1/11/10)
On a side note, can you get E85 ethanol there?
Oh and i meant £72 to fill up that's about $115!!!
I do about 250 miles a week just for work so it costs about £40 before i even have 'me time' :-(
Thread Starter
Heel & Toe
Joined: Jan 2010
Posts: 18
Likes: 0
From: Norfolk
http://www.whatgreencar.com/bioethanol.php
looks to be about 2p a litre cheaper but fuel economy is far worse + there's the tuning /installation required.
looks to be about 2p a litre cheaper but fuel economy is far worse + there's the tuning /installation required.
