Welcome to the Corvette Forums at the Corvette Action Center!

Octane question

RS84Syr

Well-known member
Joined
Jan 12, 2002
Messages
47
Location
Syracuse, NY, USA
Corvette
1984 Red/Graphite Auto 66k Z51
I've read a few posts recently with references to
octane. Seems a lot of people are burning 90+
octane.

When I got my '84 in '96, I didn't know
what to burn, so I looked at the owner's manual.
Guess what - it says 87+. Based on all the articles
I've read, octane does not directly impact power unless
your engine is tuned for high octane. High compression
engine, HyperTech chip, etc.

Having said this, I still burn at least 91.
For some reason it just "seems" better, even though
I do not think there is a performance difference.

Anyone out there burning 87?
 

Edmond

Well-known member
Joined
Aug 1, 2001
Messages
5,218
Location
Louisiana
Corvette
2003 Z06
I go either 92 or 93, depends which station I'm at.

I believe that they want you to burn a higher octane because it burns "cleaner" and you'll get less deposits, etc... in the car.
 

Ken

Gone but not forgotten
Joined
Jan 30, 2001
Messages
8,236
Location
Hermosa Beach, CA
Corvette
1987 Z51 Silver Coupe
It's true, you don't need to spend the money on high octane fuel if your engine is stock and in tune. But then, I've never been known as a "spendthrift". ;)

_ken :w
 
Joined
May 29, 2002
Messages
8,655
Location
Missoura Ozarks
Corvette
2012 💯 4LT GS Roadster
I always go for the best . . . :upthumbs

Hey, it's my Vette :cool
 

Edmond

Well-known member
Joined
Aug 1, 2001
Messages
5,218
Location
Louisiana
Corvette
2003 Z06
I sometimes use an STP fuel injector cleaner, maybe once every other month. Seems like it gets the MPG past 16.
 

RS84Syr

Well-known member
Joined
Jan 12, 2002
Messages
47
Location
Syracuse, NY, USA
Corvette
1984 Red/Graphite Auto 66k Z51
Good inputs.
Is 92 "better" than 87 if it doesn't improve performance?
I'll have to check into the "burning cleaner" thing.
Hadn't heard that before. Sticking with the high stuff
anyway. Why mess with success.

I'm just glad gas $ aren't through the roof like
they could be. 87 is $1.45 and 92 is ~$1.73
here in CNY.
 

mikevochis

Member
Joined
Jun 8, 2002
Messages
20
Location
CT
Corvette
03 50th Convert, 91 & 94 coupes & 96 Collectors
I saw the same thing in my 86 manual and also ran 87 for a long time. I also would run some injector cleaner through the system twice a season. I started running 94 because my friends told me if I drive a vette the least I could do is pay 20 cents more and run the good stuff. I noticed no difference. Now I have to run 94 because of my chip.
 

regalniz

Well-known member
Joined
Apr 8, 2002
Messages
194
Location
vegas baby vegas
Corvette
94 Polo Green Convertible w/auto
Octane

If you dont have a compression ratio high enough to burn higher octane fuel, you will notice no difference in performance. Higher octanes require higher heat. Low compression=low heat.
 
Joined
Oct 30, 2001
Messages
2,273
Location
Glen Burnie, MD, USA
Corvette
1986 Bright Red Coupe
With the mileage on my 86 (just hit 135k this weekend), I get occasional pinging at higher RPMs if I don't run at least 92. When I first got the car last winter, I ran 87, as the manual suggested, but as the weather warmed I had to bump the octane.

FWIW, I ran a tank of 87 with Super 104+ octane booster (had it sitting around from another experiment) and it didn't help as much as a tank of straight 93. Haven't tried 93 with the booster... maybe at the track :)

[RICHR]
 
Joined
Oct 30, 2001
Messages
2,273
Location
Glen Burnie, MD, USA
Corvette
1986 Bright Red Coupe
Re: Octane

regalniz said:
Higher octanes require higher heat. Low compression=low heat.

Oh, before I forget - not sure if you meant it this way, but you've got it backwards. Higher heat requires higher octane - the octane rating of a motor fuel is how well it resists combustion. You get knock when your engine is hot or higher compression and the fuel ignites in the cylinder before it's supposed to (or ignites from multiple sources, like hot spots on the cylinder walls). The knock you hear is the piston under pressure while it's still partly on the upstroke and being bounced around.

[RICHR]
 
1

1DOWN6TOGO

Guest
it's all about heat and compression.
i have lots of both so i use 93 nothing less, with an occasional octane boost that my baby seems to enjoy. she runs happier in high rpm first gear, when my tranny struggles most.
i have an issue with mid range octane.
in TX, they have 87-89-93, and on an average, you may see prices like this- $1.40-$1.50-$1.60
why is it that midrange octane, is median price, yet not median octane rating? anyone understand that?
 
B

boblx2a

Guest
I have a buddy who owns a 92 Buick Skylark and swears it runs better and gets better mileage on "high test" (whatever that is) but I think he has what I call the "drivers syndrome." Which is defined as whatever the driver pays for works! Be it spark plugs oil filters or any other outrageously priced after market stuff he can come up with.

My .02 worth is that Octane is the knock quotent of gasoline. Unless you are running a chip or some other mod in these older C4's you can easily get by with 87 octane. I too have on occasion used premium, which in our state is 91 octane. But only because they wre out of 87 octane or some such nonsense. I too have thad the pump jocky say something like, " What, put regular in a Vette? You have to be kidding!" And somehow it amazes them for me to reaffirm that I want 87 and not 91 octane. Since there is not much occasion to floor a Vette that is a daily driver I don't know if it has preignition at WOT. But thoretically it should not have.

..........
 
E

Eagle85C4

Guest
My 85 has a chip and when I run 92 or 93 the SYS light comes on with the knock sensor code...but if I run 87 or 89 it runs just as well but no SYS light. Comes on only when cruising at hiway speed. Now before ya'll go jumping...new knock sensor....all new ignition, new exhaust, new o2 sensor, set timing per manual at 6º bdc, replaced all vac hoses. Car otherwise runs perfect...just does not like "high test" or anything over 89. Guess I should not complain...saves me money....
 

RS84Syr

Well-known member
Joined
Jan 12, 2002
Messages
47
Location
Syracuse, NY, USA
Corvette
1984 Red/Graphite Auto 66k Z51
Great-
Everyone burns something different for different reasons.
But that's OK. I think it is really a leap for some people to
believe that higher octane (ie more $) is not really "better".
Octane relates to combustion timing. Higher compression
engines need higher octane. Higher octane is more $
because it is a specialty item. Being a golfer, I can relate this
to the fact that sometimes you hit the ball just as far with
the $50 driver as you do the $400 driver.

Rick
 
C

charley88

Guest
I use 87 octane 95% of the time. When I use the 93 octane, I seem to burn it faster, ie. fewer MPG. Just curious if anyone else noticed this.
 
Joined
Jun 20, 2002
Messages
2,509
Location
Tallahassee, FL
Corvette
none right now :(
I know my Vette tells me to run Premium... I am pretty sure my '93 LT1 vette was the same... Is this just an LT4 thing, or an LT1 and LT4 requirement. I assume all L98's were ok on 87 octane
 

Corvette Forums

Not a member of the Corvette Action Center?  Join now!  It's free!

Help support the Corvette Action Center!

Supporting Vendors

Dealers:

MacMulkin Chevrolet - The Second Largest Corvette Dealer in the Country!

Parts/Accessories:

Vetteskins

Advertise with the Corvette Action Center!

Double Your Chances!

Partners

Top Bottom