At the pumps
Le Mans Master
Joined: May 2004
Posts: 5,866
Likes: 60
From: Hellinois
Finalist 2020 C4 of the Year - Modified
I have to agree with CFI-EFI here. Run the lowest octane you can find, if it knocks then move up to a higher octane. I'll bet you never make it to the 93 octane level. I have to run 93 in my '85 BUT, I have 11:1 compression ratio. When it was all stock it ran just fine on 89.
Pro
Joined: Mar 2008
Posts: 579
Likes: 2
From: High Bridge New Jersey
Of course
I have to agree with CFI-EFI here. Run the lowest octane you can find, if it knocks then move up to a higher octane. I'll bet you never make it to the 93 octane level. I have to run 93 in my '85 BUT, I have 11:1 compression ratio. When it was all stock it ran just fine on 89.
BUT this is a Corvette not a Yugo! To obtain maximum performance, premium fuel is RECOMMENDED (not REQUIRED).
Do you want to cheap out or derive the performance the vehicle was designed to deliver?
THAT is the the choice.
If you wanted economy you should have bought a economy car!
Pro
Joined: Aug 2009
Posts: 522
Likes: 3
sure you could use 87, but you might as well use 93, if you like your car to run is best. 93 is usually 20 cents more expensive, so lets say 20 gallons its going to cost you 4 extra dollars over 87. big deal, thats only 1.6 gallons of regular gas you are losing out on. Using $2.50 87.
Instructor
Joined: Oct 2002
Posts: 121
Likes: 0
From: Hanover Ontario
here's a question for those of you that might know: Is it better to go with lower octane fuel that has no ethanol in it as opposed to a fuel that has a higher octane rating but also contains 10% ethanol? I always try to buy Shell gas because they don't have ethanol in the gas. The premium (V-Power) at Shell has a 91 octane rating. I could get 93 octane but it has ethanol. Which is better?
Le Mans Master
Joined: May 2004
Posts: 5,866
Likes: 60
From: Hellinois
Finalist 2020 C4 of the Year - Modified
Have you ever heard of covering your ***? That is why the manual states to use premium. The manual goes into a car built in Kentucky but will be shipped all over the world, High altitude, low altitude, hard drivers, easy drivers, hill country, flat country and who knows how many other different driving conditions. If you are not savvy enough to know what your car is doing, then by all means, buy the premium.
Le Mans Master
Joined: Feb 1999
Posts: 6,470
Likes: 2
From: levittown pa. usa Even a bad day with my `Vette, is better than a good day at work
St. Jude Donor '10
If you want to follow the "ME TOO" crowd, fill it with dollar bills. The "nothing is too good for my baby", group feels better when they throw money at their cars. Octane has one purpose, and one purpose only. It suppresses and/or prevents knock. If your mug is full of coffee, do you keep filling it, for "insurance"? Once the mug is full, you are done, for now. What spills, is unused and wasted, just like more octane than you can use. If your engine doesn't knock or the computer isn't pulling timing because the knock sensor is detecting and reporting knock counts, adding octane is useless and a waste of money. The best gasoline value for you and your car is the lowest octane that doesn't allow knock. Engines vary, as do driving styles, and environments. The best for your car, may not be the best for my, identical, car. If you will experiment, you can save yourself some money AND improve your performance. One way the higher octane gasoline suppresses knock, is to burn slower, reducing cylinder pressures. Just about every modification you do to your car to increase performance is designed to raise the cylinder pressure for more power. If you know what is what and how things work, the answer is obvious.
RACE ON!!!
RACE ON!!!
BINGO!! Now Here is a man who knows what he is talking about
Le Mans Master
Joined: Dec 2006
Posts: 5,139
Likes: 482
From: H-Town Texas
Don't fill it with dollar bills, it is difficult to get them in the gas tank to start with, they clog the filter and the lines, and if they do make it to cylinder, they do not combust very well. I agree, you are better off putting gasoline in it. You might as well put premium in it as that is what GM recommends and the cost is what $2-$3 more per fill up? Come on, give me a break.
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
You are a "Corvette not a Yugo" owner. You can display the knowledge and intelligence associated with such ownership and make the appropriate choice, not one based on ego or emotions.
Is there any good reason not to both, "cheap out" AND "derive the performance the vehicle was designed to deliver?"
RACE ON!!!
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Instructor
Joined: Jul 2009
Posts: 238
Likes: 0
From: CA
If you want to follow the "ME TOO" crowd, fill it with dollar bills. The "nothing is too good for my baby", group feels better when they throw money at their cars. Octane has one purpose, and one purpose only. It suppresses and/or prevents knock. If your mug is full of coffee, do you keep filling it, for "insurance"? Once the mug is full, you are done, for now. What spills, is unused and wasted, just like more octane than you can use. If your engine doesn't knock or the computer isn't pulling timing because the knock sensor is detecting and reporting knock counts, adding octane is useless and a waste of money. The best gasoline value for you and your car is the lowest octane that doesn't allow knock. Engines vary, as do driving styles, and environments. The best for your car, may not be the best for my, identical, car. If you will experiment, you can save yourself some money AND improve your performance. One way the higher octane gasoline suppresses knock, is to burn slower, reducing cylinder pressures. Just about every modification you do to your car to increase performance is designed to raise the cylinder pressure for more power. If you know what is what and how things work, the answer is obvious.
RACE ON!!!
RACE ON!!!
i run 10.7 compression( afr 195 street heads) and i am experimenting with 89 octane and it runs faster, stronger and better than premium and no pinging at 95 degree weather...
really it is steroids for free, higher volatility fuel, not hampered by slow burn octane additives....
i'll go to 87 on my next fill and see what happens, maybe just half a tank, so i can dilute it if it is awful
Last edited by SmokinRide; Sep 20, 2009 at 10:51 PM.
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Listen for knock. Better yet, scan it while driving. If you cannot induce knock counts, try a lower octane gasoline. As suggested, you don't, and shouldn't fill it. If you run into problems, smaller quantities can be easily diluted with higher octane gasoline, if you need to raise the octane of what is in your tank. For test purposes, run the tank fairly low. Add enough of the "test gas" to make it most of the gas in the tank. If you have no problems, add more of the same as you use up the diluted or mixed fuel until you have only the test gas in the tank. If you don't get knock or knock counts, you can repeat the procedure with the next lower grade or octane fuel, until you have determined the least wasteful, most powerful, octane gasoline to buy.
It all depends on your frame of reference. 10.4 is fairly high for a stock production engine. Mine is 9.0:1, so comparatively, yours is high. Next to a 12:1, 13:1, 14:1 etc. race motor yours is mundane.
RACE ON!!!
Instructor
Joined: Jul 2009
Posts: 238
Likes: 0
From: CA
dynamic compression ratio and static ratio comes into mind, aluminum heads and cast iron comes to mind, every combo is different, if you need it then get it if not then don't
tuning can smooth things up as well there is just too many variables...
they call it trial and error
tuning can smooth things up as well there is just too many variables...
they call it trial and error
Drifting
Joined: Jun 2002
Posts: 1,945
Likes: 41
From: Corinth TX
Your car will run on 89 and the only thing you will possibly experience is a drop in mpg. Your car will simply switch stoichiometric tables based on the octane of gas you put in. Basically what happens is that when you put in gas, your car (computer) determines the correct table to run off of. Now based on the MPG that you lose in comparison to the amount of money you saved it will pretty much equal out.
For the people who say GM engineers designed the car to run perfect the way it is, alot of their engineering is also to make the almighty dollar. Performance was not their key objective. If it was, don't you think they would have come up with the best exhaust/air filter/ headers possible? The key behind their engineering is based upon min expense with max profit.
For the people who say GM engineers designed the car to run perfect the way it is, alot of their engineering is also to make the almighty dollar. Performance was not their key objective. If it was, don't you think they would have come up with the best exhaust/air filter/ headers possible? The key behind their engineering is based upon min expense with max profit.
Melting Slicks
Joined: Aug 2007
Posts: 2,619
Likes: 1
From: Salem Oregon
St. Jude Donor '09-'10-'11
The main reason I use premium in mine is that I want to keep it ALWAYS in top running condition, and I am not willing to put in lower octane just to save a few bucks now just to end up MAYBE having to pay for it later down the road.
As the old adage goes, an ounce of prevention is worth a pound of cure.
Its kind of like do you want to put on cheap parts now only to have them break sooner, or would you rather put on the better quality now to prevent having to constantly fix the same problem?
I personally dont want to have to worry about fixing a pinging, loss of mileage, poorer performance or whatever.
Laura
As the old adage goes, an ounce of prevention is worth a pound of cure.
Its kind of like do you want to put on cheap parts now only to have them break sooner, or would you rather put on the better quality now to prevent having to constantly fix the same problem?
I personally dont want to have to worry about fixing a pinging, loss of mileage, poorer performance or whatever.
Laura
Le Mans Master
Joined: May 2004
Posts: 5,866
Likes: 60
From: Hellinois
Finalist 2020 C4 of the Year - Modified
With that high of a number I have to think that Europe uses a different way to calculate octane rating, you only need to do what has been described here, start with just a little of the lowest octane available, if you have no knock or pinging and the car performs as it should then you are set to go, if you encounter problems then step up the octane one level.
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
dynamic compression ratio and static ratio comes into mind, aluminum heads and cast iron comes to mind, every combo is different, if you need it then get it if not then don't
tuning can smooth things up as well there is just too many variables...
they call it trial and error
tuning can smooth things up as well there is just too many variables...
they call it trial and error
Le Mans Master
Joined: May 2004
Posts: 5,866
Likes: 60
From: Hellinois
Finalist 2020 C4 of the Year - Modified
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
RACE ON!!!