I'm using regular as indicated by the manual. The engine vibrates for a while when the auto transmission shift from 3 to 4 in low rpm then returns normal as rev up. Is this normal in your driving experience? or which octane number gas should I use?
Is it regular 87 Octain(sp) or (?). Your operators manual should tell you what octain rated fuel to use with that model vette (87, 89, 91, 93, 94 etc). I would not put anything less than 89 octain with that year motor being around 9.5 to 1 CR. Your computer will adjust the timing so you don't get a knock or ping by either advancing or retarding and it sounds like that is what is happening at low RPMs. You are loosing power when this happens and unless you don't want that power it's a good idea to use a higher octain where you don't have the bogg at low RPM's. You may also be surprised with your milage if you use a higher octain fuel. You could get more MPG's which will offset the price differential.
I am running regular-grade 87 octane for daily driving or crusing in my 87. This motor has a ZZ3 (older) cam and some port matching. I can hear just a bit of knock at WOT just after shifting from a lower gear. It runs just fine for daily driving and freeway use with that grade of gas. Mileage is averaging around 24-26 on the freeway with 70MPH speeds. I change over to premium 92-octane before autocross or track events.
My 92 gets only premium 92 octane stuff. On a trip to Monterey, CA last year, I couldn't find much more that 91 octane (Chevron, Texaco, Union 76) but that seemed to work OK. I tried some 89 octane stuff once and it didn't run right at all.
Thanks for your replys!
Mine is '86. It's runs fine at rpm above 1200 or so, or in every other gears instead of 4th in low rpm. The engine lacks power when vibration happen. So I have to press the pedal deeper to make the transmission kick down to bring the rpm up. It might be a kind of engin knock. Maybe it is time to try 93 oct.
Thanks for your replys!
Mine is '86. It's runs fine at rpm above 1200 or so, or in every other gears instead of 4th in low rpm. The engine lacks power when vibration happen. So I have to press the pedal deeper to make the transmission kick down to bring the rpm up. It might be a kind of engin knock. Maybe it is time to try 93 oct.
Why nor run down the tank and fill it back up with the premium stuff. This way you can see if it improves any. You could also pick up a pint of Octane104 for a boost.
I hope nobody minds me adding to this old tread. I thought I might as well ask a question about fuel octane on an already existing tread on the same subject.
Anyway I run my corvette on 98 octane BP Ultimate. I do not know if this will garner a performance increase on a stock L98. Am I wasting my money?
Another reason I chose this fuel is because it is cleaner and better refined then regular. Apparently it has only 50ppm (parts per million) of sulphur content which is 10 times less then the National Australian Standard. Is this worth the extra 6 cents per liter?
Another thing I notice looking though some of these treads regarding fuel octane is that a lot of people run between 87-93 octane. This seems extremely low as in Australia we use between 92-98 octane. Would I be right to assume that in America you use a different system of rating octane to what we use here?
I use premium from BP which is Amoco fuels. the owners manual states you can run lower octane gas but it retards your timing which equals a loss of power. If you have a chip like i do from hypertech you can not run lower grade gas.
I have to disagree I have run the lower octane before i had done anything to my vette and to say the least it ran like crap. It had substantial power loss throughout the RPM band. It is cheap insurance when you pull up next to that Mustang to get a little extra ponies out of it. In my opinion your car will like you alot better with premium .
From the time I started putting gas in I always used 93 octane from amoco. Now it is BP and i still use the premium. Around me all they offer is 87,89, and 93. I have changed brands of fuel and used premium and the car ran terrible. I used phillips once and that was a mistake.
I understand that, indeed, there are differing methods of achieving the octane number. I am not sure that it is a 'standard' even in the same country, among various brands.
If your car is stock, follow the owner's manual. Many drivers run premium fuel and only drain their wallet faster.
My stock '84 seemed to run better with premium as the computer adjusted things. I knew a lot less about the car then, so all of that is seat-of-the-pants lore.
Perhaps there is some carbon build-up in the older engine which alter the flame characteristics. Such might show improvement with a higher grade.
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