I've been told that I can put regular gasoline in my 1980 L-82 without any consequences. It's all stock except for the exhaust. Is this true?

 

It'll run without damage, but will most likely get some pinging or deiseling under power or shutdown. I got some crap 92 at an Exxon today and added some octane booster and it seemd to fix it.

 

your car was designed to run on the lowest octaine available. if you get ping, go to the next higher one untill it stops. if still pinging,try retarding your timming a couple of degrees.

 

My '80 L-82 is stock and runs fine on 87 octane; no pinging, no dieseling. She likes 92 octane and I treat her to a tank full of the good stuff periodically. I do not run any type of octane boost in her.

 

 

GM "recommended" premium gasoline for all Corvettes, being that they are performance vehicles. They will, however run on 87 octane fuels without damage.

At most, you'll take a minor hit in performance (or so they say).

Brian.

 

I remember reading that in the mid 70s GM decreed that the Corvette engines must run on 91 octane, which set the maximum compression ratio to a little over 9.0:1, with the max being 9.1:1. That's why the L-82 has a 9.0:1 CR.

I'vr also read that the octane ratings method used in the seventies is no longer used and that the 'premium' fuel of the mid seventies (91 octane) is now equivalent to 87 octane by today's standards.

Can anyone confirm or set me straight on the octane rating system?

 

Your lucky, the 80 L-82 has "TRW" style forged pistons, if it's not rattling, go ahead I guess but on a hot day, you should probably run 91 octane or if you plan on driving it "hard".

 

The octane ratings of leaded fuels is lower than the octane ratings of unleaded fuels due to the lead additives providing the "anti-knock" characteristics that is provided by the higher octane today.

I found an article that tells you more than you'd ever want to know here: http://www.faqs.org/faqs/autos/gasoline-faq/part1/

Here is a part that explains how the pump-octane is derived:
4.10.3 Antiknock Index ( aka (RON+MON)/2, "Pump Octane" )
The ( Research Octane Number + Motor Octane Number ) divided by two. Limits
are not specified, but changes in engine requirements according season and
location are discussed. Fuels with an Antiknock index of 87, 89, 91
( Unleaded), and 88 ( Leaded ) are listed as typical for the US at sea level,
however higher altitudes will specify lower octane numbers.

So you basically have a choice to run the lowest octane rating you can until the engine starts to ping and knock (or run the lowest and add an octane booster) and/or retard the timing, or run the fuel that seems to make your car the happiest

I had a problem with a truck of mine knocking really bad on anything under 91 octane gas. I took it in and they retarded the timing about 3 degrees and the issue has been gone ever since. Retarding the timing makes the cylinder run cooler, so you don't have the same issues with pre-ignition (which is what the extra octane is there to prevent).

The higher octane gas is intended to keep the gas stable and prevent it from igniting during the compression stroke. The higher the compression, the hotter the air will get and the greater the chance that the gas will ignite before the spark.

As with everything, your mileage may vary and what works for me may not work for you. I have no expectations of gas prices dropping significantly, so if you can tune to 87 octane gas, you might save a bit of money over the long haul.

One other thing to deal with is the reformulated gas that is out there. I live in an area that uses it, and I know that it does not behave as well as normal gas nor do I get the same economy from it. Fortunately, I can buy regular gas and I avoid the RFG whenever possible.

This is probably one of those "no simple answer" items that there will be many opinions, and most of them right.

Brian.

 

I also have run 87 octane from the pump with a bottle of 104 added to bring it to around 94.