Switching to regular grade fuel
Popular Reply
11-03-2015, 09:14 AM
Le Mans Master
You're an absolute fool if you put low octane fuel in a high performance, high compression engine.
Sure these engines, as well as the LS's, have the ability to react to detonation and "protect" themselves, essentially driving "fine". The issue is, you're causing the engine to essentially detune itself in a somewhat crude manner. This will certainly impact many factors over the long term...things like hydrocarbon buildup within the cylinders (making the chamber more knock prone), accelerated wear on the catalytic converters, etc. In addition, in order for the motor to protect itself, it can't PREDICT knock, it has to experience it first, then react to it. So, you're causing the engine to repeatedly go through this process of have cylinder pressure spikes occur that ring the piston crown, stress the engine internally, place huge loads on the rod bearings....all to save like 10 bucks...that's just plain stupidity.
Sure these engines, as well as the LS's, have the ability to react to detonation and "protect" themselves, essentially driving "fine". The issue is, you're causing the engine to essentially detune itself in a somewhat crude manner. This will certainly impact many factors over the long term...things like hydrocarbon buildup within the cylinders (making the chamber more knock prone), accelerated wear on the catalytic converters, etc. In addition, in order for the motor to protect itself, it can't PREDICT knock, it has to experience it first, then react to it. So, you're causing the engine to repeatedly go through this process of have cylinder pressure spikes occur that ring the piston crown, stress the engine internally, place huge loads on the rod bearings....all to save like 10 bucks...that's just plain stupidity.
10-31-2015, 04:30 PM
#3
Race Director
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For max performance, you want the higher octane fuel since our engines have the highest compression ratio of any engine I know about (11.5 to 1). Now if you only drive at moderate power levels, especially in winter, regular should be fine.
10-31-2015, 04:34 PM
#4
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Tech Contributor
Not interested in engine knock, this is a high compression V8, ill stay with 91 or higher. I like Chevron.
This whole vid is about econoboxes, not C7’s......
This whole vid is about econoboxes, not C7’s......
Last edited by Glen e; 10-31-2015 at 04:36 PM.
10-31-2015, 04:37 PM
#5
also, the c5 in the video has 10.1 to 1 compression ration, so that 1.4 difference between it and the 11.5 to 1 in the c7 is major, in my opinion.
Last edited by senah; 10-31-2015 at 04:52 PM.
10-31-2015, 04:42 PM
#6
10-31-2015, 04:53 PM
#7
Le Mans Master
I put regular in my wife's Lexus IS250 which recommends premium. No change in performance-cheaper price. For my C7- only premium and 93 octane not 92. I am not going to skimp on a 70K car-I paid for max performance if I want it in my car, and for the few times I really step on it-why get a lower performing gas- to save 3 bucks?
10-31-2015, 05:20 PM
#9
10-31-2015, 05:54 PM
#10
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Let me first say that after 10 years owning a C6 and now a month with my C7, I have never used anything less than 92 octane in either but check out this link:
http://www.chevroletcorvetteusa.com/c7-specs
Quote: Recommended fuel:
premium recommended, not required
http://www.chevroletcorvetteusa.com/c7-specs
Quote: Recommended fuel:
premium recommended, not required
10-31-2015, 06:15 PM
#11
Race Director
10-31-2015, 06:51 PM
#12
Team Owner
Makes no sense at all what is to be gained except a couple of bucks when filling up.
10-31-2015, 06:56 PM
#13
Burning Brakes
I just can't believe this issue keeps coming up every so often. Paid $2.39 a gallon today for top tier 93 octane. So this can't really be about saving $4 per tank, can it? But even when gas was $4/gallon, its just the price of poker. With the low miles most of us put on our Vettes, the annual amount just isn't all that much. I want to save money as much as the next person. These are high performance sports cars not Malibus.
10-31-2015, 07:04 PM
#14
Race Director
For normal cars it is a waste, especially for a standard Civic. For the Vette that can actually use the octane, premium is great.
Can you use it in a Vette? Yes, in most cases although the engine computer will limit performance. In Utah it is about $.35 difference, back east I noticed it was $.50-.60.
Can you use it in a Vette? Yes, in most cases although the engine computer will limit performance. In Utah it is about $.35 difference, back east I noticed it was $.50-.60.
10-31-2015, 07:17 PM
#15
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St. Jude Donor '15
"In honor of jpee"
Just so you'll really know the difference, figure out what you'll be saving on a monthly basis.
Many/most regular gas costs 30 cents-40 cents less per gallon. Let's say you get 23 mpg on premium over the entire year's driving, and assume you get the same on regular which you may or may not. Even if you drive 1,000 miles per month (some will do more, many will do less), that's 12,000 miles per year. Pick a number for regular gas cost per gallon, say, $2.10; then, per the above say 35 cents more for premium, or $2.45 per gallon.
So, here it is:
12,000 miles per year divided by 23 mpg = 522 gal. used
522 X $2.35 per gal. premium = $1,226 per year Premium gas
522 X $2.10 per gal regular = $1,096 per year Regular gas
$1,226-$1,096 = $130 per year saved.
That works out to $10.81 per month saved. It's your decision to see if it's worth it.
You can work it out on just a month's worth of miles, too.
And if you don't know your mpg (miles per gallon) just take your total dollars spent for a year, or a month and divide by total gallons bought. For a month, say, $1,000 divided by 43 gal. That equals 23 mpg.
Fill in your own numbers.
PS If my math is off, I know I'll be told.
Many/most regular gas costs 30 cents-40 cents less per gallon. Let's say you get 23 mpg on premium over the entire year's driving, and assume you get the same on regular which you may or may not. Even if you drive 1,000 miles per month (some will do more, many will do less), that's 12,000 miles per year. Pick a number for regular gas cost per gallon, say, $2.10; then, per the above say 35 cents more for premium, or $2.45 per gallon.
So, here it is:
12,000 miles per year divided by 23 mpg = 522 gal. used
522 X $2.35 per gal. premium = $1,226 per year Premium gas
522 X $2.10 per gal regular = $1,096 per year Regular gas
$1,226-$1,096 = $130 per year saved.
That works out to $10.81 per month saved. It's your decision to see if it's worth it.
You can work it out on just a month's worth of miles, too.
And if you don't know your mpg (miles per gallon) just take your total dollars spent for a year, or a month and divide by total gallons bought. For a month, say, $1,000 divided by 43 gal. That equals 23 mpg.
Fill in your own numbers.
PS If my math is off, I know I'll be told.
10-31-2015, 07:51 PM
#16
Safety Car
with 11.5 to 1 compression ratio, you need premium. on regular the engine controls will retard the timing and inject more fuel when necessary to prevent detonation, so your mpg will decrease and it will likely cost you more money per mile than if you use premium, plus you'll lose horsepower.
also, the c5 in the video has 10.1 to 1 compression ration, so that 1.4 difference between it and the 11.5 to 1 in the c7 is major, in my opinion.
also, the c5 in the video has 10.1 to 1 compression ration, so that 1.4 difference between it and the 11.5 to 1 in the c7 is major, in my opinion.
Use 93 if available!!
10-31-2015, 07:56 PM
#17
Drifting
I admit up front that I only watched the first few minutes of the video, so if there were any parts about effects on cars tuned for premium, I didn’t have enough patience to get as far as those parts. But if you look at it from the perspective of the 90+% of cars on the road that are tuned for regular, what I saw makes sense. They get absolutely no benefits from premium, and we suffer for it. If there weren’t so many dummies buying premium that didn’t need it and get no benefit from it, the price would come closer to the true extra cost of making it, which is about 10 cents over regular.
For cars tuned for premium, yes, they can generally run on regular, protected by their knock sensors to retard timing (supercharged versions are usually protected only to mid grade octane, not regular). Mileage will fall a bit, but not enough to offset the extra cost of premium. There will be a measureable loss of power. The power loss isn’t huge. It certainly won’t turn the car into a slug, perhaps costing half a second in 0-60 time. But the biggest risk to me is that you will be depending on the knock sensors to keep you away from engine damaging detonation. Seems like a dumb risk to me.
For cars tuned for premium, yes, they can generally run on regular, protected by their knock sensors to retard timing (supercharged versions are usually protected only to mid grade octane, not regular). Mileage will fall a bit, but not enough to offset the extra cost of premium. There will be a measureable loss of power. The power loss isn’t huge. It certainly won’t turn the car into a slug, perhaps costing half a second in 0-60 time. But the biggest risk to me is that you will be depending on the knock sensors to keep you away from engine damaging detonation. Seems like a dumb risk to me.
10-31-2015, 08:15 PM
#18
Team Owner
I would be more interested in knowing if 91+ actually does have a higher octane rating than 87, who's to really know?
10-31-2015, 09:51 PM
#19
Drifting
Nobody can categorically guarantee you’ll never get cheated. However, there are enough checks and balances in the system to insure that odds of getting cheated on octane are very nearly zero. Besides the threat of a customer who really needs premium complaining and causing tests to be run, there are multiple layers of recordkeeping throughout the distribution system to insure that premium sales match premium deliveries, and spot checks against specs at stations even if there haven’t been complaints. And perhaps the biggest reason of all is that the gas station only pays the refiner a bit more than the extra cost of making premium, so a cheating station owner would only save the roughly 10 cents per gallon extra cost to make premium, not the inflated 40-60 cents difference in pump price.
10-31-2015, 09:54 PM
#20
Safety Car
I put regular in my wife's Lexus IS250 which recommends premium. No change in performance-cheaper price. For my C7- only premium and 93 octane not 92. I am not going to skimp on a 70K car-I paid for max performance if I want it in my car, and for the few times I really step on it-why get a lower performing gas- to save 3 bucks?
So if you want to drive like a little old dying man, regular will suffice. If you want to drive it like the performance car it is, IMHO, use Premium.