What Fuel Octane ????
Thread Starter
Instructor
Joined: Feb 2003
Posts: 154
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From: Bethalto Illinois
What Fuel Octane ????
I have an 86 L-98 Vette. I have had the car for over a year and always put premium (93 octane) in the car...
I finally read the owner's manual (surprise!!) and it says the car should have 87 octane...regular unlead gasoline!?!?!?!?!
My understanding is that too high an octane is not only a waste of money, but can cause carbon buildup in the cylinders and a host of other problems...
So, I started to run a few tanks of mid-grade (89 octane)...I some how can't bring myself to run regular gas in a Vette.
One thing I did notice is that the perpetual SES code 32 (EGR) quit coming on when I drove the car...could the improper octane really cause this problem??
What octane do other early C4 owners use and recommend??? thanks :cheers:
I finally read the owner's manual (surprise!!) and it says the car should have 87 octane...regular unlead gasoline!?!?!?!?!
My understanding is that too high an octane is not only a waste of money, but can cause carbon buildup in the cylinders and a host of other problems...
So, I started to run a few tanks of mid-grade (89 octane)...I some how can't bring myself to run regular gas in a Vette.
One thing I did notice is that the perpetual SES code 32 (EGR) quit coming on when I drove the car...could the improper octane really cause this problem??
What octane do other early C4 owners use and recommend??? thanks :cheers:
Race Director
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From: I live in my own little world
NC Events Coordinator
Re: What Fuel Octane ???? (zog)
IMHO...i'd run whatever octane i know the Vette performs well with. If it's 93...fine. If there's not a noticeable difference in performance with 87, why spend the extra $3-4 at each fill-up for premium?
Burning Brakes
Joined: Aug 2003
Posts: 899
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From: Copperas Cove TX
Re: What Fuel Octane ???? (Alchemist)
I have used nothing but regular unleaded (87) and no trouble at all. You people who use the higher octane, these rich oil companies LOVE you. Cost you at least 20 cents a gallon more, costs the oil companies about 2 cents a gallon more to make it.
HAVE A GREAT DAY!!! SPEND THAT MONEY!!!!!!!!!!!
:flag :flag
HAVE A GREAT DAY!!! SPEND THAT MONEY!!!!!!!!!!!
:flag :flag
Race Director
Joined: May 2001
Posts: 14,165
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Re: What Fuel Octane ???? (zog)
Woohoo! I get to be the first guy to use this guy on a thread :beatdeadhorse: :beatdeadhorse:
The short of it is that you want to use the LOWEST octane fuel that your car will burn while still maintaining full spark advance. Meaning that if your car pings on 87 and has to retard the timing it will run just fine but you're giving up performance. Meanwhile if it can run full spark advance on 87 without detonating you are simply throwing your money away by going with anything higher.
:cheers:
Save your money and put in the cheap stuff
The short of it is that you want to use the LOWEST octane fuel that your car will burn while still maintaining full spark advance. Meaning that if your car pings on 87 and has to retard the timing it will run just fine but you're giving up performance. Meanwhile if it can run full spark advance on 87 without detonating you are simply throwing your money away by going with anything higher.
:cheers:
Save your money and put in the cheap stuff
Team Owner
Joined: Sep 2001
Posts: 62,119
Likes: 1,725
From: Athens AL
C7 of the Year - Unmodified Finalist 2021
C4 of Year Finalist (performance mods) 2019
Re: What Fuel Octane ???? (zog)
The highest grade I use is the 89, usually 87 though, the 86 with Iron heads doesnt need the octane. The compression ratio is too low.
Code 32 doesnt come from that. Its a EGR switch/solenoid failure. Extended part-throttle running on the hwy at over 170F will open the EGR. Your pipe could also be plugged, or you just need to tighten your gas cap (vacuum loss)
Code 32 doesnt come from that. Its a EGR switch/solenoid failure. Extended part-throttle running on the hwy at over 170F will open the EGR. Your pipe could also be plugged, or you just need to tighten your gas cap (vacuum loss)
Le Mans Master
Joined: Dec 2002
Posts: 6,715
Likes: 2
From: Santa Teresa New Mexico
Re: What Fuel Octane ???? (vetteboy88)
Some cars require 93. A L-98 runs fine on mid grade, but 87 will choke a lawn mower. If the tank opening says 93 then 93 it is.
My Mercedes says 93 and thats a $10,000 motor so I use 93 in it.
My Mercedes says 93 and thats a $10,000 motor so I use 93 in it.
Le Mans Master
Joined: Oct 2002
Posts: 7,178
Likes: 1
From: Bahston Mass.
Re: What Fuel Octane ???? (Nathan Plemons)
Woohoo! I get to be the first guy to use this guy on a thread :beatdeadhorse: :beatdeadhorse:
The short of it is that you want to use the LOWEST octane fuel that your car will burn while still maintaining full spark advance. Meaning that if your car pings on 87 and has to retard the timing it will run just fine but you're giving up performance. Meanwhile if it can run full spark advance on 87 without detonating you are simply throwing your money away by going with anything higher.
:cheers:
Save your money and put in the cheap stuff
The short of it is that you want to use the LOWEST octane fuel that your car will burn while still maintaining full spark advance. Meaning that if your car pings on 87 and has to retard the timing it will run just fine but you're giving up performance. Meanwhile if it can run full spark advance on 87 without detonating you are simply throwing your money away by going with anything higher.
:cheers:
Save your money and put in the cheap stuff
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Race Director
Joined: May 2001
Posts: 14,165
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Re: What Fuel Octane ???? (JB666)
Your serious, the LT1 will run, with no problems, on -92 octane gas?????? I'm serious, I've NEVER put anything under 92-93 in, and with prices the way they are, it's been killing me!!!!! This would come as a relief!!
On the older TPI cars with lower compression there is no need for the higher octane fuels.
Burning Brakes
Joined: Aug 2003
Posts: 899
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From: Copperas Cove TX
Re: What Fuel Octane ???? (dieseltech)
Forget the so called detergents most of them were taken out years ago because of pollution issues. Check your owners manual and go by it. Most of you driving early C-4's can use regular and a bunch of you with later C-4's can too. Don't let this big mystique of " I've Got a Wonderful Corvette" get between you and the big bucks you are paying for gas that you don't need and it's probably doing more harm than good.
HAVE A GREAT DAY!!!
:flag :flag
GM recommends using high detergent fuel. Premuim grade generally contain higher detergent levels than regular.
:flag :flag
Le Mans Master
Joined: Oct 2002
Posts: 7,178
Likes: 1
From: Bahston Mass.
Re: What Fuel Octane ???? (Nathan Plemons)
Your serious, the LT1 will run, with no problems, on -92 octane gas?????? I'm serious, I've NEVER put anything under 92-93 in, and with prices the way they are, it's been killing me!!!!! This would come as a relief!!
It will run with no problems on lower octane fuel, HOWEVER you'll probably be giving up some power. The LT1 makes 10.5:1 compression from the factory and specifically calls for premium. To know for sure you would really need to data log the car and see if you are getting any detonation and spark retard on lower octane fuels. The reverse flow cooling does help the LT1 in running the higher compression ratio.
On the older TPI cars with lower compression there is no need for the higher octane fuels.
It will run with no problems on lower octane fuel, HOWEVER you'll probably be giving up some power. The LT1 makes 10.5:1 compression from the factory and specifically calls for premium. To know for sure you would really need to data log the car and see if you are getting any detonation and spark retard on lower octane fuels. The reverse flow cooling does help the LT1 in running the higher compression ratio.
On the older TPI cars with lower compression there is no need for the higher octane fuels.
Instructor
Joined: Dec 2003
Posts: 106
Likes: 0
From: McHenry IL
Re: What Fuel Octane ???? (redwing76)
Some cars require 93. A L-98 runs fine on mid grade, but 87 will choke a lawn mower. If the tank opening says 93 then 93 it is.
My Mercedes says 93 and thats a $10,000 motor so I use 93 in it.
My Mercedes says 93 and thats a $10,000 motor so I use 93 in it.
Drifting
Joined: Apr 2000
Posts: 1,879
Likes: 1
From: Lockport, IL Let's get em ALL home soon!
Re: What Fuel Octane ???? (89Corvette6spdFX3)
I not only run 87 but I buy the CHEAPEST gas I can find since Joe Blows' gas Shell, Mobile and everyone else's will usually be formulated AND delivered in the SAME tanker trucks from the same refinery. The extra additives that are said to be in the "better" gases are a myth. "Believe it or don't."
Race Director
Joined: May 2002
Posts: 10,306
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Re: What Fuel Octane ???? (Vetterin)
I not only run 87 but I buy the CHEAPEST gas I can find since Joe Blows' gas Shell, Mobile and everyone else's will usually be formulated AND delivered in the SAME tanker trucks from the same refinery. The extra additives that are said to be in the "better" gases are a myth. "Believe it or don't."
Yes most gas comes in the same tankers but each company has their own set of detergents and most studies show its good to change from gas station to gas station every few months. AMMACO & BP are my favorite.
Almost all the brands are good, Shell, BP, AMMACO, HESS the list goes on and on but to buy Gas from Cheap places like the starvin Marvin down the road with the mystery no name gas---- no thanks. I have seen too many problems with bad tanks and or water in them.
