Octane Requirements 1979
Thread Starter
Cruising
Joined: Aug 2007
Posts: 11
Likes: 0
Octane Requirements 1979
I don't want to open too big a can of worms here but..
My new to me 79 came with all sorts of documents and factory manual but no owner's manual.
What is the recommened octane level for the 79 L82 engine, been using high test to be safe?
Adrian
My new to me 79 came with all sorts of documents and factory manual but no owner's manual.
What is the recommened octane level for the 79 L82 engine, been using high test to be safe?
Adrian
Intermediate
Joined: Jul 2004
Posts: 49
Likes: 0
From: Novi MI
1979 Unleaded Fuel
According to the Owners Manual, Page 5-1, "Your gasoline engine is designed to use ONLY UNLEADED gasoline. Unleaded gasoline must be used for proper emissions control system operation." There is no mention of the octane requirement. On Page 7-2, the Compression Ratio for the L-82 engine is only 8.9 - 1. My guess is that the car would probably run on regular, but to be safe, a mid-grade or premium, would probably be better. Maybe someone more familiar with the engineering aspects of engines could shed more info on this.
Safety Car
Joined: Dec 2004
Posts: 4,876
Likes: 1
From: Jersey Shore Exit 98
Your 79 will run on 87 which is regular. if it pings run the next higher octane. it can't hurt to run premium most do and the cost is less then a $1.80 more to fill the tank w/the good stuff.
Last edited by Jims79; Aug 23, 2007 at 12:31 PM.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,117
From: Crossville TN
In '79 you could still find stations that had upwards of 100 octane (if you knew where to find them). But your '79 C3 only needs regular unleaded gas. As mentioned, if you get some pinging, adjust the advance or buy the mid-grade of gas. Premium gas in that car is a waste of money, IMO.
Racer
Joined: Aug 2005
Posts: 435
Likes: 2
From: Boise Idaho
I understand regular will work assuming stock timing..
But
What about those that have the timing advanced per the Lars Papers?
Does that make any differance?
I use premium anyway and don't mind wasting the money that way as I find many other ways to waste it on this car. lol
But
What about those that have the timing advanced per the Lars Papers?
Does that make any differance?
I use premium anyway and don't mind wasting the money that way as I find many other ways to waste it on this car. lol
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,117
From: Crossville TN
Just to help clarify.... Lars instructs us as to the BEST way to set up your engine for best performance and operation. The factories DIDN'T set them up for optimum performance for two reasons: 1) it took more time and, therefore, cost more to do; 2) retarded timing might generate less emissions, but it definitely produces less power...which translates to LOWER WARRANTY COSTS. Lars knows that your engine can operate properly (better, IMO) when mechanical advace is set to 34-36 degrees max and when it all comes in around 2500-2800 rpm. The engine is designed to handle that and not ping. GM didn't go to that trouble. I just had Lars redo my carb and distributor for my '71 [low compression] engine. It never ran better since I've had it, it doesn't ping on regular gas and it is more economical than before. What's not to love?
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
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
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
Drifting
Joined: Aug 2006
Posts: 1,694
Likes: 0
From: Oregon
My 80 was to run on 87, but I rarely did. My crate is also to run on 87. Ive only put 87 in once and didnt think it was worth the risk. When fuel is in the $3 range, what is another 20 cents....
Just my opinion
Just my opinion
Team Owner
Joined: Jun 2000
Posts: 38,923
Likes: 1,481
From: Southbound
Cruise-In II Veteran
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,117
From: Crossville TN
Higher octane = higher horsepower = better power performance = more $$$. Higher octane will not hurt the car (other than you will wear the engine out sooner). Lower octane will not hurt the car as long as it is not pinging. Use whichever you like for your "reasons".
Drifting
Joined: Feb 2005
Posts: 1,738
Likes: 2
From: San diego ca
Run the lowest octane gas that doesnt allow detonation (ping) anything more doesnt improve performance and just spends your money.
If you modify the engine, the same holds true...higher compression - more advance - run whichever octane eliminates ping..(probably a higher grade)..but dont run any more than you need...thats just money down the t*let.
no harm will come to your engine if you run higher than necessary octane, but all things being equal, higher octane will not improve performance unless you need it.
If you modify the engine, the same holds true...higher compression - more advance - run whichever octane eliminates ping..(probably a higher grade)..but dont run any more than you need...thats just money down the t*let.
no harm will come to your engine if you run higher than necessary octane, but all things being equal, higher octane will not improve performance unless you need it.
I can't believe that this myth is still around.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,117
From: Crossville TN
Mike,
1) Please explain how a higher octane fuel..with better burn characteristics...would NOT generate more power out of an engine.
2) There were lots of (older) C3 cars that didn't have catalytic converters in 1979. The statement made above was that no such "hi-test" gas was available in '79. Not true.
1) Please explain how a higher octane fuel..with better burn characteristics...would NOT generate more power out of an engine.
2) There were lots of (older) C3 cars that didn't have catalytic converters in 1979. The statement made above was that no such "hi-test" gas was available in '79. Not true.
Race Director
Joined: Jul 2001
Posts: 15,892
Likes: 42
Mike,
1) Please explain how a higher octane fuel..with better burn characteristics...would NOT generate more power out of an engine.
2) There were lots of (older) C3 cars that didn't have catalytic converters in 1979. The statement made above was that no such "hi-test" gas was available in '79. Not true.
1) Please explain how a higher octane fuel..with better burn characteristics...would NOT generate more power out of an engine.
2) There were lots of (older) C3 cars that didn't have catalytic converters in 1979. The statement made above was that no such "hi-test" gas was available in '79. Not true.
http://en.wikipedia.org/wiki/Octane_rating
http://chemistry.about.com/gi/dynami...tos/octane.htm
The availability of high octane gas allows either OEMs or home builders to configure engines with higher compression ratios, more adventurous ignition maps and/or cam characteristics. It is these features in the engine that produce the increased power, not the gas itself.
2) Please re-read my post. I said no super UNLEADED gas in 1979. There was plenty of leaded super gas available, as well as regular leaded. If you had super unleaded available in your area, that's nice. None was available here.
