My thread on which gasoline to use generated some great discussion. I also learned about top tier gas which I think I will start using at least when racing. Some vette owners mentioned using 87 octane gas. The following web page at cars.com lists the negative aspects of doing this including higher engine temperatures, lower fuel economy and shortened engine life:

http://www.cars.com/carsapp/national...odaysgas1.tmpl

Cheers

 

dont use reg fuel & my experience & my 2 cents >>> on regular fuel ......... the computer will retard timeing , running reg fuel & will lose hp & tourque, simple physics........I have a 66 BB 427 ,I retarded timeing to use mid grade & can feelt the diminished power & throttle response...........immediately put timeing back where it should be & 93 fuel & life is good again

regarding my C6 I drove 1300 miles in october all around Nova Scotia in my c6 (great trip, great people) & used the premuim fuel that was available ...had slight engine nock, came home filled up with 93 .....nock gone just thinking the premium in Nova Scotia must have been lower octaine & below 91 ........ The Dog

 

Only if Top Tier gas is not available will I use something different....and always 93 octane

 

A tank fill up regular to prem gas cost $3-$4 more. Why would anyone want to put the bare minimum gas in a car such as this with high compression. Yes the computer can compensate but was not meant to on a daily basis. It's not worth it.

 

We didn't buy our Vettes to save money, but to enjoy in its full potential.

 

Woof

 

When all else fails you can read your owner's manual.


Gasoline Octane
If your vehicle has the 6.0L V8 engine (VIN Code U),
use premium unleaded gasoline with a posted octane
rating of 91 or higher. You may also use regular
unleaded gasoline rated at 87 octane or higher, but
your vehicle’s acceleration may be slightly reduced,
and you may notice a slight audible knocking noise,
commonly referred to as spark knock. If the octane is
less than 87, you may notice 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. If you are
using gasoline rated at 87 octane or higher and you hear
heavy knocking, your engine needs service.
If your vehicle has the 7.0L V8 engine (VIN Code E),
use premium unleaded gasoline with a posted octane
rating of 91 or higher. For best performance, use
premium unleaded gasoline with a posted octane
rating of 93. In an emergency, you can use regular
unleaded gasoline with an octane rating of 87 or
higher. If 87 octane fuel is used, do not perform any
aggressive driving maneuvers such as wide open throttle
applications. You may also hear audible spark knock
during acceleration. Refill your tank with premium fuel
as soon as possible to avoid damaging your engine.
If you are using gasoline rated at 91 octane or
higher and you hear heavy knocking, your engine
needs service.
Gasoline Specifications
At a minimum, gasoline should meet ASTM
specification D 4814 in the United States or
CAN/CGSB-3.5 in Canada. Some gasolines may
contain an octane-enhancing additive called
methylcyclopentadienyl manganese tricarbonyl (MMT).
General Motors recommends against the use of
gasolines containing MMT. See Additives on page 5-6
for additional information.
California Fuel
If your vehicle is certified to meet California Emissions
Standards, it is designed to operate on fuels that
meet California specifications. See the underhood
emission control label. If this fuel is not available
in states adopting California emissions standards,
your vehicle will operate satisfactorily on fuels meeting
federal specifications, but emission control system
performance may be affected. The malfunction
indicator lamp may turn on and your vehicle may fail a
smog-check test. See Malfunction Indicator Lamp
on page 3-42. If this occurs, return to your authorized
GM dealer for diagnosis. If it is determined that the
condition is caused by the type of fuel used, repairs may
not be covered by your warranty.

 

Lets see, I paid how much for my Vette and I want to save how much to use cheaper gasoline??

 

Typically 20 cents difference from 87 octane to 93 in FL. Who would not spend that small amount for protecting the engine and increased performance?

 

Problem here in Denver top tier gas is 91 oct. I know there are a couple of places where you can get 100 oct. But those stations aren't close to me.

 

There are some C6 owners who are using nothing but low octane fuels. I don't think they realize what they are doing to their engines. Remember, with a vette, gasoline is just liquid entertainment.

 

Great Post. Thanks

 

Nope. Replacing fuel injectors is not my most favorite thing to do.

 

I brought my car into the dealer for 2 new fuel sensors. I had half a tank going in, and they charged me 21.40 for gas because they had to drain and re-fill.

I got my supercharger put on the next day, and on the first Dyno they noticed timing rapidly dropping. They stopped imediately and looked at all the tables. Everything was where it was supose to be. We were all sitting around with our thinking caps on, and I said that the dealer put new gas in my tank when I went to get the new sensors. So, I called the dealer and asked which station they used for the fill up...they said, "Oh, we just use the pump in the back." I wasn't too happy to say the least. We drained the gas and filled her up with 93 octane and she purred like a tiger.

I saw, first hand, what 87 will do...and it's not worth it!

John

 

Quoted from your link: "Retarding the spark causes a richer fuel/air mixture, which decreases fuel economy, increases emissions, causes the engine to run hotter, and reduces the longevity of both the engine itself and the catalytic converter."

Retarding the spark does not cause a richer fuel/air mixture...that is controlled by the O2 sensor. As such, emissions will not increase either. Engine temperature is controlled by the thermostat and fans...octane has no effect on either of them. And exactly what mechanism reduces the life of the engine and catalytic converter??? I would love to hear that one. The spark is not retarded in all situations either. However, when it is, fuel economy will decrease...but only during those situations. It is federal law that all cars be capable of running 87 octane fuel with no increase in emissions and minimal decreases in fuel economy.
Can you imagine GM recommending fuel (as shown from the owner's manual abve) that would harm the engine (warranted to 100k miles) or catalytic converter (warranted to 80k miles under the long term emissions warranty)?
While I understand people wanting to run premium (and to each their own), there's really no reason not to run 87 octane in the winter or at higher altitudes like the guy from Denver. Lower temperatures and higher altitude make knock less likely. My daughter (who is a poor college student) uses 87 octane in her '99 'Vette in the winter while I've run nothing but 93 octane in my ZR1 since brand new. To each their own!

 

I ran 87 for a few weeks when gas was $3.60+!
I did not notice any performance loss, but then again my wife drove the car most of that time!

 

You can find many sources stating that the engine will run hotter. Things are not happening when they should when you retard the timing. Exhaust valves open before fuel mix is finished burning and their temperatures go up. Also, lower octane fuel burns faster than high octane.

 

Provide links to the "many sources" and we'll see how many of those sources are credible. Remember, anyone can put anything they want on the internet whether it's right or wrong...including me. If the lower octane fuel burns faster, then that compensates for the retarded timing and everything comes out the same temperature.

But the octane rating of a fuel is not a measure of its' burn rate, just its' resistance to self ignition. There is 118 octane racing fuel that burns faster than 87 octane pump gas...it has to. When you're running a 500 cu in pro stock engine with a huge bore at 10,000 RPM, the flame front has a long way to travel across the combustion chamber in a very short period of time.

If (and that's a big if) the exhaust valve runs a little hotter, it isn't much or you'd end up with burnt valves. Regardless, the engine operating temp remains the same.

 

yep....

 

The last sentence was the one I was hoping for. People refer too often to fuel grade as being equated to quality of a fuel. Octane slows the burn rate and 87 burns faster with less byproducts. The rule with all cars is to use the minumum octane needed to run your engine. Honda makes a point to say 87 is the best choice but the average guy equates cheap cost with cheap quality so they buy the 'good stuff' which is bad for the car. Excess octane is bad for your car. The average corvette owner is better off with higher octane but there is zero chance of actual knock on this car. It pulls timing to assure it cant happen and then reverts to a lower octane table to ensure safe operation. 87 cannot cause pinging in this car.

Once modded of course, (and I'm sure lots of 700rwhp S/C car owners are about to jump on me to say they dyno less with 93 as oposed to 95 octane) yes..... your car needs the added octane.

The cleanest running engine is a low compression motor optimized for 87. Once you mod your vette, longevity is compromised just from the added stress. I beleive the LS series engines are good for 300k miles so after the cam and heads at 500rwhp expect it to drop to 125-150K.