I can't believe people are to cheap to spend a little extra for premium. It the manufacture recommends a certain fuel there is a reason for it. All fuel are not the same,I hate it when people say that.

Think about it this way. If your car is under warrenty, and you suffer engine failure, the first thing the dealership will do is pull a sample of fuel. If its not the recommended grade,that is negligence of the owner and they will not cover the repairs.

 

I spent +5 years over at LS1tech as I built up my Z28. Let me tell you, the Search Button/Dead Horse responses were even worse over there. All the newer members would 're-ask' all those basic newbie questions and most of the friendlier veteran members would patiently try to help them out. Instead of using the 'Dead horse' or 'use the search button' response, I just ignore the post and move on to the next one.

Oh yeah, premium all the way!

 

BP had a cool display at Bloomington Gold. They had some technician/engineers there that could answer all the octane questions. BOTTOM LINE...use 91 or better.

 

I Agree

 

Lucy says to use regular gas in the Corvette.

 

93-octane premium (91-94) seems the way to go, regular, I believe would be a
I've noticed a few threads on this subject also, but nothing wrong with helping a newbie....

 

http://auto.howstuffworks.com/engine1.htm

I know this is a simplistic illustration but helps explain. Wera32 was also right that the actual introduction of the spark might occur slightly before the top dead center (TDC) and that pre-combustion is the fuel/air mixture igniting BEFORE the introduction of spark on the compression stroke. It is igniting from compression and heat, rather than with the spark. But it is happening even sooner before the piston reaches TDC.

Again, a higher octane fuel RESISTS combustion so that it only ignites when the plug sparks, not before.

Many car's timing is set BTDC (Before TDC) as indicated on older engines with a timing mark on the crank balancer. This is where you find out if your timing is retarded or advanced. Spark BTDC or AfterTDC.

So, that "ping" or "knock" you hear is exactly that....pre-ignition. It can eat holes in piston tops...bad for rings, wristpins, connecting rods right on down the line.

Now I'm no expert so take this however you want, but when someone says a little knock under power doesn't do any damage, they need to re think that big time. And hopefully keeping this in mind will help.

Any other motorhead input is welcome here.

 

Regular gasoline...just say no!

 

+1...

did you buy a corvette to be an economy car? trade it in for a prius if you can't afford the gas....or a turbo diesel vw...45 mpg...and like 100 hp WOOO

the only way i can see using 87 octane is okay...is if you were running methanol injection with 100% methanol (effectively taking the octane rating to well over 93 octane) but who wants all that gook in it...

gas prices do suck...not as bad as in other countries. corvette= performance machine

 

Comments like this make me never want to buy a used car.

 

Quote:
Originally Posted by Oh 2 Fun
Does everyone really understand what the "Octane rating" means????!!

It's all about when the fuel/oxygen mix ignites under compression.

The higher the octane, the longer the fuel resists combustion.

The lower the resistance, the more chance you have that the "combustion" will occur BEFORE the piston reaches top dead center.

When this happens, the combustion occurs while the piston is still travelling UPWARD. Total resistance and pounding. Damage.

pre-detonation

With a higher resistance to combustion (high octane), the firing of the fuel/oxygen mixture happens later in the compression stroke so the piston is more likely to be already on the DOWNstroke. Hello...more power....no knocking......less damage.

Nuff said??

I hope so,....I'm exhausted.....

Quote:
Originally Posted by wera32
Ignition is timed to occur before TDC, not after. Pre-ignition means spontaneous ignition occurring before the spark is provided by the ignition system, not that it's occurring before TDC, which is normal.


By me: Tricepv v v v v

Excuse my ignorance, but I believe that this is the point where this thread stops condescending and adds its value in knowledge. Am I to understand that "detonation" is the equivalent to "knocking?" What is the precise time in the pistons stroke for combustion? When you speak of "knocking/pinging", is this because there are TWO separate combustion incidents? Are there more?

If so, it would make total logical sense that 'detonation' could in fact be prevented by the use of fuel with a HIGHER octane rating, no?

I believe that there has been a misunderstanding as far as fuel efficiency and financial efficiency are concerned. There lies some irony in the fact that one would spend the money it takes to buy a Corvette only to turn around and decide that modesty/frugality are now the objective. Trying not to be judgemental, but would one also take their car to the car wash? Run "used" tires? Throw trash in the passenger seat?

I am being facetious.

Seriously though, someone please explain how this whole "combustion/pre-egnition-TDC" thing works so I can understand.

Truly seeking knowledge...<---------- (he is with me)


Thanks, Oh 2 fun.

 

yer more than welcome....

 

This topic comes up every year at Corvette's at Carlisle and their C5/C6 Troubleshooting sessions. The speaker is C4/C5 Specialist on another Forum and he provides the following reference to Top Tier fuels and the mfg.'s (including GM) who initiated the idea of a finer grade of fuel and the refiniries and stations who sell the top tier fuel.

http://www.toptiergas.com/index.html

 

When we buy our next car, I will seriously take into consideration whether it needs super or not. My wifes Maxima needs it, and obviously the Vette does too. But while we have either one, it's super they get. The Vette doesn't bother me, but the Maxima?

 

For crying out loud, we are talking about $.30 a gallon. If that puts a crimp in your "budget" well, like one member put it, you bought the wrong car and should of bought a Ford Pinto. If I was poor and was on the verge of having to use regular gas in order to eat, I would get a part time job. The book says 91-93 and it gets just that. Nothing else.

 

FWIW- I always go with the octane rating the manufacturer recommends.

Sure with anti-knock sensors you can probably run regular in a pinch.

Even if you exclude the potential for engine damage- you are not extracting the most potential powerwise if you go with a lower octane fuel than the engine was engineered to run. Since the Corvette is a performance vehicle- what would be the point of doing that?

Honestly- if the price difference between regular and premium is hurting your budget- do yourself and your family a favor and trade the car for a Corolla or Prius - these are fantastic reliable and economical cars if MPG is an issue. Or get a little 2 seater like my wife's MR2 Spyder which calls for regular octane and is a hoot to drive.

Me- I'll keep my Z06 and fill her with Chevron Supreme.

Just my 2 cents

 

IDK how much this will be considered OT, but it led me here.

I do NOT notice smaller lines at the Starbuck's drive-thru, I do NOT see that anyone has suddenly decided to stop smoking, I don't notice people eliminating bottled water (tap water usually has BETTER quality) and I don't see fast-food chains hurting (don't see huge headlines in the paper either)...

If ya gotta skimp somewhere, make fuel grade for your Vette the LAST choice.

Or park it.

Only my opinion. Has to be said. <------he is with ME!

 

Well, I was the first to respond to this thread, so I'll be the first to admit naiveté regarding this issue. I thought there really was no harm/no foul in using regular gas in this car.

My Camry recommended premium but I used regular. This 'Vette is no Camry and I need to get into the mindset of treating it like a 'Vette and not like a Camry. Old habits die hard.

Thanks to all well-meaning members for setting the record straight and for your usual shoot-from-the-hip guidance for all us newbies.

s'noJob

 

I'll give this a shot.

In simplistic terms, gasoline engines are designed to run on fuel that burns (albeit very fast). So, octane rating can indicate a fuels resistance to detonate (explode instead of burn). This is all related to compression ratio because the higher the compression ratio, the more likely lower octane fuel will explode instead of burn when ignited.

Most all engines try to fire the mixture via spark plug before top dead center (btdc). How far btdc is determined by compression ratio and octane (remember that this is being simplistic and other factors also determine this stuff like load, temperature, chamber design etc). So for a given compression ratio, using lower octane fuel would induce detonation that's sensed by knock sensors. The computer then retards timing (adjusts timing toward tdc) in an effort to eliminate the knock. If high octane fuel is used, then timing can be more aggressive(further btdc).

All this relates to engine power in that the further btdc you can start the burn (not detonate), the better head start the burning mixture has to expand and start pushing the piston as it goes over the top and starts down. It then should be easy to see that higher octane and the accompanying advanced timing should give better power and efficiency as well as better economy. It should also be clear that engines that are designed for regular fuel will not get better power or economy with high octane fuel since they do not have compression ratios or ignition timing that can make use of the higher octane fuels.

As to what you should use, my owner's manual does not say not to use regular in emergency, if you can't get premium etc. It simply says acceleration may be reduced.

"Gasoline Octane
Use premium unleaded gasoline with a posted octane of
91 or higher for best performance. You may also use
middle grade or regular unleaded gasoline rated at
87 octane or higher, but your vehicle’s acceleration may
be slightly reduced. If the octane is less than 87, you
may get a heavy knocking noise when you drive. If this
occurs, use a gasoline rated at 87 octane or higher
as soon as possible. Otherwise, you might damage
your engine." (Quote from owner's manual)

 

Trying to bring this discusion back to the most relevant issue because this is important.

Does anyone here disagree that pre ignition (pinging/knock) is bad for the LS1?

If not, its smart to spend $.10c a gallon to ensure your high compression LS1/LS6 engine is not damaged.