PREMIUM Gas

Stallion · 09-18-03, 09:19 PM

Do you guys put Premium in your Vettes? I do. Is that higher octane level necessary? I don't mind the money, but I would like to know about it.

What causes the need for higher octane? Compression? Timing?

Thanks!

Stallion

C3forME · 09-18-03, 09:57 PM

Your L48 is designed to run on 87 octane regular gas. Assuming your car is stock and tuned properly it should run fine on it. With the gas prices what they are today why give the money to the gas retailers when you could put into upgrading or restoring your car.

Stallion · 09-18-03, 10:03 PM

I see. But what is the tech behind the idea of higher octane needed?

Thanks!

froggy47 · 09-18-03, 10:07 PM

Minimizes detonation (high compression engines & other high performance situations. If you're not detonating it's wasted.

(This is really over simplified but I gotta go out & drive the Vette)

MaineShark · 09-19-03, 12:59 AM

The only other thing that is has is more detergent additives to keep your engine clean. But adding a bottle of concentrated detergent ("fuel injector cleaner" - available everywhere) every fourth tank or so will do a better job.

Joe

WhalePirot · 09-19-03, 02:43 AM

Burn what your car was designed for; that which the manual states. Running lower than specified octane on later cars will cause knocking, picked up by the sensor, detuning the engine.

I was looking for the piece I saw, written by a GM fuels engineer, that stated that their research found the 2-3 tanks of detergent gasoline cleaned filthy injectors on a Firebird, as well as, and cheaper than the aftermarket stuff.

The following adds warning to the additives.

Gasolines and Fuel Additives...

09-19-03, 03:55 AM

No choice. I have an LT4. Premium is REQUIRED. (10.8:1 out of the factory with lots of low RPM torque). But in California, the best I can get is 91 octane. I keep wondering how much better this sweet motor will perform with 93 octane in her.

Stallion · 09-19-03, 09:12 AM

Okay, thanks for the replies. I figured it was compression related. Maybe I should start using regular. I'll check my owners manual and see what GM says about the octane.

Stallion

Gorgon · 09-19-03, 09:52 AM

There is more to premium fuels than just detergents.

Octane is added to retard combustion. The more octane is used the higher compression and temperature the fuel-air mixture can tolerate. You remember from your chemistry class: PV=nRT As P(pressure) increases so does the tempurature of the mixture. As temperature increases the mixture can combust on its own before the spark comes in from the spark plug. This causes your engine knock. The octane allows the mixture to tolerate higher pressures and temperatures without ignition so that the mixture can be ignited at the correct time with the spark from the plug.

And that concludes our chemistry lesson for the day.

Leon

Stallion · 09-19-03, 12:23 PM

Quote:

Originally posted by Gorgon
There is more to premium fuels than just detergents.

Octane is added to retard combustion. The more octane is used the higher compression and temperature the fuel-air mixture can tolerate. You remember from your chemistry class: PV=nRT As P(pressure) increases so does the tempurature of the mixture. As temperature increases the mixture can combust on its own before the spark comes in from the spark plug. This causes your engine knock. The octane allows the mixture to tolerate higher pressures and temperatures without ignition so that the mixture can be ignited at the correct time with the spark from the plug.

And that concludes our chemistry lesson for the day.

Leon

I remember that equation! Thanks, I do understand now.