C6 fuel
Team Owner
Joined: Sep 2000
Posts: 25,015
Likes: 2,709
From: Far NW 'burbs of Chicago
St. Jude Donor '13
If using low octane fuel, you are depending on the knock sensors and timing retard to protect your engine from destruction. That's not the way i want to do things.
There are enough other things that can go wrong, don't add another one to the list.
There are enough other things that can go wrong, don't add another one to the list.
Drifting
Joined: Jan 2005
Posts: 1,942
Likes: 1,328
From: Houston Tx
Originally Posted by Hoonose
Somewhere in the manual it states for C6 to use 93 octane for maximum performance. I don't have access to a manual now...
The next possibility is to cover themselves against use of cheap gas. What gets posted is (R+M)/2 octane, but most cars are more sensitive to M than to R number. It is cheaper to make R number in a refinery than M number. So one of the dirty little tricks that a disreputable refiner can use is make 91 by, for example, 98R+84M, rather than the reputable way of 96R+86M. If you have a bit of extra R+M, it is more difficult to get M below 86.
The last possibility is to cover yourself against an aging engine. As the engine ages, deposits and other irregularities will increase octane requirement by a number or two. So by the time you get our to 75,000 to 100,000 miles, your car that started out needing 91 can actualy be up to needing 93.
Safety Car
Joined: Oct 2005
Posts: 3,775
Likes: 19
From: Santa Clara, CA
While owning my C-5, I went long periods of time using 87 octane and could not tell the difference from the 91+ octane. The only vehicles where higher octane was relevant for me was for the VW busses when driving over mountains. The higher octane eliminated knocking.
My rule is and always will be, if you feel the difference, use the higher octane. I challenge the CF gang to have someone pump the gas for each of you a couple of times without telling you what the octane level is. If you do a true blind study like this, I believe you will come to the same conclusion as I - higher octane is a psychological booster, not a performance booster. Save the bucks and spend them on C6 mods!
My rule is and always will be, if you feel the difference, use the higher octane. I challenge the CF gang to have someone pump the gas for each of you a couple of times without telling you what the octane level is. If you do a true blind study like this, I believe you will come to the same conclusion as I - higher octane is a psychological booster, not a performance booster. Save the bucks and spend them on C6 mods!
Last edited by humvet; Mar 27, 2006 at 11:40 PM.
Melting Slicks
Joined: Oct 2005
Posts: 2,057
Likes: 0
My wife drove my car this weekend and put gas in it. I suspect that she used 87 octane because when I would accelerate, the engine would make noise. It sounded like noisy valvetrain chatter. The car seemed to accelerate okay but this dang noise was driving me crazy!!! I checked everything underhood and all seemed intact. I suspected the bad gas because she's done it before. I filled up with premium 93 octane and also added a bottle of octane boost and, voila, the noise is gone. 87 octane may be ok for regular engines, but 93 is what high compression engines need. you run the risk of knocking if you use the low octane stuff. Use the high octane. Your car will thank you for it. 
Race Director
Joined: Jan 2006
Posts: 18,396
Likes: 169
A friend of mine has an identical Hemi Ram truck as mine (except color), down to the bed rails and fender lip chrome. I use 87 regular. He uses 93 preminum. My truck will pull him about half a car in the quarter. I have never had a minutes trouble from this truck. Told him the money I save in fuel helped pay for the Vette. 
But I do use 93 preminum in the Vette.
But I do use 93 preminum in the Vette.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Instructor
Joined: Mar 2006
Posts: 153
Likes: 0
From: chicago il
Originally Posted by tak
In the engine mapping there are two sets of adjustments for the car to run on. One is with lower timing.
Logic says that if you use lower grade fuel it will use the lower performance set, and thus your engine will be safe. You will not have the 400 bhp and 400 lb/ft torque though.
This was seen using the LS2 edit
Logic says that if you use lower grade fuel it will use the lower performance set, and thus your engine will be safe. You will not have the 400 bhp and 400 lb/ft torque though.
This was seen using the LS2 edit
if your c6 is running on the lower octan table, you will lose 10-20hp or more depends on how big of a knock it is.
Team Owner
Joined: Feb 2000
Posts: 53,524
Likes: 77
From: Arizona
Originally Posted by LDB
I don't remember seeing that other than for Z06 which I mentioned in my earlier response. But if it's there, I could think of three possible explanations. The least likely is that under normal circumstances, you'd benefit because the car is really tuned for 93. If that were the case, it's hard for me to understand why the manual wouldn't just say 93, rather than say 91 with some obscure buried footnote about 93.
The next possibility is to cover themselves against use of cheap gas. What gets posted is (R+M)/2 octane, but most cars are more sensitive to M than to R number. It is cheaper to make R number in a refinery than M number. So one of the dirty little tricks that a disreputable refiner can use is make 91 by, for example, 98R+84M, rather than the reputable way of 96R+86M. If you have a bit of extra R+M, it is more difficult to get M below 86.
The last possibility is to cover yourself against an aging engine. As the engine ages, deposits and other irregularities will increase octane requirement by a number or two. So by the time you get our to 75,000 to 100,000 miles, your car that started out needing 91 can actualy be up to needing 93.
The next possibility is to cover themselves against use of cheap gas. What gets posted is (R+M)/2 octane, but most cars are more sensitive to M than to R number. It is cheaper to make R number in a refinery than M number. So one of the dirty little tricks that a disreputable refiner can use is make 91 by, for example, 98R+84M, rather than the reputable way of 96R+86M. If you have a bit of extra R+M, it is more difficult to get M below 86.
The last possibility is to cover yourself against an aging engine. As the engine ages, deposits and other irregularities will increase octane requirement by a number or two. So by the time you get our to 75,000 to 100,000 miles, your car that started out needing 91 can actualy be up to needing 93.
Team Owner
Joined: Feb 2000
Posts: 53,524
Likes: 77
From: Arizona
Originally Posted by EuroRod
A friend of mine has an identical Hemi Ram truck as mine (except color), down to the bed rails and fender lip chrome. I use 87 regular. He uses 93 preminum. My truck will pull him about half a car in the quarter. I have never had a minutes trouble from this truck. Told him the money I save in fuel helped pay for the Vette. But I do use 93 preminum in the Vette.
But I do use 93 preminum in the Vette.
Racer
Joined: Feb 2005
Posts: 487
Likes: 0
From: Snohomish WA
Originally Posted by ShockwaveTXB
Regular is "acceptable" because it's the law.
The car was designed to run on Premium, the fact that you can run it on regular is a requirement by law, but not what's meant for optimal performance.
Also, do you buy a Corvette so that your experience is only "satisfactory?"
The car was designed to run on Premium, the fact that you can run it on regular is a requirement by law, but not what's meant for optimal performance.
Also, do you buy a Corvette so that your experience is only "satisfactory?"
