C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

Gas Prices!!

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Old Mar 12, 2008 | 05:33 PM
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Default Gas Prices!!

How bad will my "93 LT1 run on 89 Octane gas, fuel prices are going through the roof and if I can reasonable shave a few bucks I would like to. Although not at the cost of destorying my motor.
Old Mar 12, 2008 | 06:59 PM
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What ever your gas prices are in the us, they Cant be a patch on the £1.05 ( $2.10 ) per litre for standard and £1.12 ( $2.24 ) per litre for premium we pay her in the uk, and its going up ever week!!

Sorry i know it dont help with your question but it might make you feel better!!
Old Mar 12, 2008 | 07:24 PM
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I have a 90 so it might not be the same, but in my owners manual it states I can use 89 octane but I might encounter engine knock and poor acceleration. I've never used anything lower then 92.

Last edited by jimmers; Mar 12, 2008 at 07:32 PM.
Old Mar 12, 2008 | 09:01 PM
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the highly skilled fuel jockeys here in oregon put 87octane in my 84 last weekend, that thing ran horrible, so i would advise against it
Old Mar 12, 2008 | 09:31 PM
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Originally Posted by ZfidyONE-84
the highly skilled fuel jockeys here in oregon put 87octane in my 84 last weekend, that thing ran horrible, so i would advise against it
It must be time to blow the carbon out of that thing. The 9.0:1 compression ratio L83 doesn't have enough compression to blow out a match. Mine hasn't had anything higher than good old 85 octane for decades.


saber7469,
The ONLY thing octane does is suppress knock. If it doesn't knock or pull timing because the ESC gets activated, with lower octane gasoline, you have sacrificed nothing. The higher octane gasoline only boosts your ego, not your cars performance if it doesn't knock. Wait until the tank gets really low. Then put in 10 gallons or so. If it pings or has problems, you can always dilute it with the high dollar stuff.

RACE ON!!!
Old Mar 12, 2008 | 10:12 PM
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Originally Posted by CFI-EFI
saber7469,
The ONLY thing octane does is suppress knock. If it doesn't knock or pull timing because the ESC gets activated, with lower octane gasoline, you have sacrificed nothing. The higher octane gasoline only boosts your ego, not your cars performance if it doesn't knock. Wait until the tank gets really low. Then put in 10 gallons or so. If it pings or has problems, you can always dilute it with the high dollar stuff.

RACE ON!!!
Doesn't the car get better MPG on the octane that it's tuned for? I remember hearing people talk about how you'd get slightly worse MPG by switching to 87 (thus defeating the purpose to some degree), and wondering if there was any truth to that.
Old Mar 12, 2008 | 10:26 PM
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Originally Posted by LouisvilleLT4
Doesn't the car get better MPG on the octane that it's tuned for? I remember hearing people talk about how you'd get slightly worse MPG by switching to 87 (thus defeating the purpose to some degree), and wondering if there was any truth to that.
No!
Old Mar 12, 2008 | 11:13 PM
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Originally Posted by LouisvilleLT4
Doesn't the car get better MPG on the octane that it's tuned for? I remember hearing people talk about how you'd get slightly worse MPG by switching to 87 (thus defeating the purpose to some degree), and wondering if there was any truth to that.
If you have an LT1, use the recommended octane (91). 87 or 89 cannot hurt the engine, but you will suffer fuel economy and performance losses as the ECM dials back your timing in response to input from the knock sensor. I have tried the lower octane fuel in mine and the difference is very noticeable (especially the 87 stuff).
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Old Mar 12, 2008 | 11:28 PM
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Guess I need to be running 87 then
Old Mar 12, 2008 | 11:40 PM
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Originally Posted by Onyx C4
If you have an LT1, use the recommended octane (91). 87 or 89 cannot hurt the engine, but you will suffer fuel economy and performance losses as the ECM dials back your timing in response to input from the knock sensor. I have tried the lower octane fuel in mine and the difference is very noticeable (especially the 87 stuff).
I've run the 89 in my 95 with slightly reduced performance due to the timing adjustments. Here however the diff between 89 & 92 is only a dime so for less than $2.00 a tank I can run the 92 but it's still costing my a *##@% $3.75/gal
Old Mar 12, 2008 | 11:55 PM
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If you are all complaining about gas, I experimented a little and set my base timing to 2 degrees. I ran about 5 gallons of 87 octane through my 383. Well ok, here are the issues. The motor lost at least 40 ft-lbs all around the rev range, the engine doesn't seem to idle as nicely, and there is a slight delay in throttle response. But actually no pinging whatsoever! I would say, either suck it up and use premium no matter what, or change your spark timing and your driving habits and all will be fine.
Old Mar 13, 2008 | 12:14 AM
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Default No mo cheap gas

Gas prices wo't be going down any time soon. If you guys think you have
high prices, consider that in Vancouver, B.C. they were charging $1.20 per liter of regular today. Premium would be about $1.35 .
A gallon of premium would be roughly $5.40. here!
This may be our last hurrah. Buy the premium and have fun while you can.
It won't be long before we go back to riding horses.
Old Mar 13, 2008 | 12:48 AM
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In south america some countries are down to 0.12 a gallon.
I have a MSD dial retard on my LT1 and run regular,I hate paying $4.13 a gallon for E10.Higher Octain just makes the fuel burn longer that is all folks
My race gas is only $8.63 a gallon C-17. My compression is 14.8 to 1 so I can't run regular .
Old Mar 13, 2008 | 08:32 AM
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First of all, to compare US gas prices to European prices doesn't work. England taxes their gas to pay for things like health care.

Anyway, I was reading recently that although gas prices are up significantly, because we are a more successful nation a much smaller percentage of our income is spent on it. I.E. in the 80's gas was nearly this expensive (with inflation factored in) and we spent like 20% of our income on it. These days the gas is technically a bit more expensive, but we're only spending like 15% of our income on it because average income has risen faster than gas prices.

Yeah, it hurts, but we aren't exactly going bankrupt if we can still buy and mod vettes.
Old Mar 13, 2008 | 10:13 AM
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The difference in cost between regular and premium here is generally 20 to 25 cents per gallon. Since I get about 22 mpg overall average that comes to about 1 cent per mile. I drive it about 1000 miles a month so the difference, with no adjustment for possilbly worse mileage/peformance is about $10 a month. I will stay with the premium and preferably Chevron. I would rather push it around than buy Citgo crap (just an added thought to keep things going).
Old Mar 13, 2008 | 11:33 AM
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Originally Posted by LouisvilleLT4
Doesn't the car get better MPG on the octane that it's tuned for? I remember hearing people talk about how you'd get slightly worse MPG by switching to 87 (thus defeating the purpose to some degree), and wondering if there was any truth to that.
NO! Octane is nothing more than a measure of a gasoline's anti-knock properties. If it doesn't knock on low octane, the only thing you get with higher octane is the ability to tell your neighbor that your Corvette is such an animal that you HAVE to use the expensive stuff. Except for rare isolated cases, super premium is for the oil companies to make excess profits from the "nothing but the best for my baby" crowd.

RACE ON!!!
Old Mar 13, 2008 | 11:47 AM
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A block heater and timer can do wonders for gas milage. Cold start uses ALOT of fuel.

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Old Mar 13, 2008 | 11:55 AM
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Originally Posted by CFI-EFI
NO! Octane is nothing more than a measure of a gasoline's anti-knock properties. If it doesn't knock on low octane, the only thing you get with higher octane is the ability to tell your neighbor that your Corvette is such an animal that you HAVE to use the expensive stuff. Except for rare isolated cases, super premium is for the oil companies to make excess profits from the "nothing but the best for my baby" crowd.

RACE ON!!!
Actually your both right. Cars are set up to run a certain octane fuel, you can tune it to change that in various ways. You only need to run the lowest octane your car will allow without knocking. I've modified mine and have a slightly higher CR than later L98's but I can still run 87 without knocking. I must admit it doesnt feel as smooth as running mid-grade. Power is the same though. I'm sure its just left over fuel not getting burnt hanging around in there smoothing it out.
Old Mar 13, 2008 | 02:17 PM
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Originally Posted by Demonic85
Actually your both right.
Both? you only quoted me.



Originally Posted by Demonic85
Cars are set up to run a certain octane fuel, you can tune it to change that in various ways.
No matter how your engine is "set up" or how you tune it, gasoline with a higher octane number than the lowest octane that doesn't knock, is a waste of octane and money.



Originally Posted by Demonic85
I can still run 87 without knocking. I must admit it doesnt feel as smooth as running mid-grade. Power is the same though. I'm sure its just left over fuel not getting burnt hanging around in there smoothing it out.
Octane has nothing to do with "left over fuel not getting burnt". Octane is ONLY a measure of knock resistance. More octane than needed produces nothing advantageous.

RACE ON!!!
Old Mar 13, 2008 | 02:42 PM
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Originally Posted by hooblyboobly
If you are all complaining about gas, I experimented a little and set my base timing to 2 degrees. I ran about 5 gallons of 87 octane through my 383. Well ok, here are the issues. The motor lost at least 40 ft-lbs all around the rev range, the engine doesn't seem to idle as nicely, and there is a slight delay in throttle response. But actually no pinging whatsoever! I would say, either suck it up and use premium no matter what, or change your spark timing and your driving habits and all will be fine.
That's because you globally retarded the timing 4 degrees (if it was set to 6* btdc originally), not necessarily due to the 87 octane fuel. I could run race fuel in my car, but if I knocked the timing back 4 degrees across the board, I'd get the same results you did. A valid experiment would have been to run the 87 octane fuel, make no other changes, and data log the amount of knock counts / spark retard before and after the octane change.



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