marcouvo

Is 100 Octane gas compatable with the C-7? Or would that mess the car up? Thought I'd like to try some, if advisable.

OBSSSD

As long as it is unleaded should be fine.

Around here there is good availability of leaded 100 gas but only for running without cats on the car.

johnglenntwo

http://www.whitfieldoil.com/www/docs/171.335

Sometimes higher octane gasoline is necessary for more power.

http://blog.hemmings.com/index.php/2...-priced-fuels/

thebishman

Unless the ECU is tuned to take advantage of the increase in octane; (in which case bye bye warranty), you aren't going to get any additional power out of the car. It's OEM tuned for 91 and I doubt you'll see very much increase at all with 100 octane, so why spend the extra $'s/gallon?

Caveat: if taking the car on a road course in high ambient temps, and the 'best' pump fuel you can get is 91, then throwing in some 100 unleaded 'race gas' is probably not a bad idea in order to decrease the chance of getting 'knocking'.

blkbrd69

If your talking about avgas 100LL aviation fuel? Its only low in lead compared to the old really nasty aviation fuels. Will kill cats and O2 sensors quickly, and also show up on an oil analysis as possible bad bearings.

If something like VP C10, Sunoco SS 100, or Torco 100, could add some to boost octane for a bit of detonation protection. If you are already running a quality 93 octane probably wont gain any HP.

lawdogg149

I tried it and it was a wasted $9.98 a gallon. I ran 2 tanks full at RD Atlanta and it didn't change anything about the car nor lap times. Im pretty sure this computer isn't relearning a new timing curve based on fuel. My old C6 Z06 however loved it and the car ran much stronger with it.

Save your money for something else I have proved the fuel does nothing for these cars.

Higgs Boson

Actually, it is pulling timing on 93 so it definitely isn't tuned for 91.

If you are able to reset your spark timing learn factor then you can take advantage of 98-100 unleaded/oxygenated fuel. I don't think it will make all that much difference though especially for the price.....that's why E85 is so popular. 1.55 by my house for race gas (E85) right now. The only difference/drawback is that you need so much of it (+30%).

blkbrd69

Wish they sold that cheap South Carolina 93 octane no alcohol in the rest of the country.

All we can get here is 93 oct with alcohol that's inconsistent as heck, or 91 octane with no alcohol for boats and its stupid expensive.

JoesC5

My C6 Z06 is factory "tuned" to run on 91, but might lose some power when running in hot ambient temps due to knock retard kicking in. But, it will run better on 93 as there is less chance of knocking at higher temps. I doubt if jumping to 100 with my factory tune is going to make any difference in power though.

This is what GM has to say about my car....

"If the vehicle has the 6.2L V8 engine (VIN Code R) or 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."

Poor-sha

I tried the same experiment at Summit Point and had the same results. Don't bother.

Higgs Boson

That's because that's what they sell at the pumps and GM knows this.

If you reset everything, put in 93 octane, the car will pull timing and learn down from the High Octane map to the Low Octane map....it just pulls and learns down more on 91. What you think is "factory tuned optimal performance" is just where your spark timing learning lands and you wouldn't know any difference. Why would you? Unless you were are big nerd like me (and some others) monitoring every aspect of your engine and/or transmission every time you drove it, you couldn't possibly. And there is nothing wrong with that considering you probably enjoy the drive a lot more than me!

Keep in mind, I am not saying you will gain 50 hp with "race gas" but I am saying there is room in the factory tune for a little more octane to maximize the spark timing. 5-10 more HP under the right conditions? Maybe. Worth 10 dollars per gallon? No way.

johnglenntwo

In case some of you don't realize it? The 91 octane is what is available in the most southern states and 93 for the most northern. The engine power potential is higher due to generally more oxygenated therefore it necessary the more north you are as a general rule and set up that way! (oxygen & octane) I don't think this was brought up above?

Higgs Boson

it has nothing to do with northern or southern states. it has everything to do with elevation. lower octane the higher your elevation.

for example, Texas is a southern state, 93 octane available everywhere except el paso, which is at something like 4500 ft.

johnglenntwo

I was hoping to a least get cleared up on that! I used to live in LA's San Fernando Valley which is over 1k ft so it makes sense there that it was lower octane and 91 as you said. I never noticed it being any different anywhere else down there. Here in Oregon I am at around 200 ft. and 92. Canada and north 93, but, again altitude and air density (oxygen) right there playing a role I'm sure. Scottsdale AZ and my sisters house ~1200ft, yep makes perfect sense!

Thanks again!

johnglenntwo

And if the air is humid and hot displacing evenmore oxygen living at 1000ft don't even bother, as I have heard (Just making smoke)!

DA!

johnglenntwo

http://www.smartcarofamerica.com/for...question-6268/

Z06Norway

You will need as good gas as possible, if your engine doesn't take advantage of the 94 octane, then its a waste of money and actually loose power. The lower octane rating the faster the burn rate of the fuel.

BUT i can't believe that GM didn't give us the potensial to extract power potensial form the 6.2 liter supercharged engine by tuning for 94 octane ?

Here in Europe we have 102 octane but different rating, so it is close to 96 octane (R/M)/2

And it does wonders for high performance engines

ChrisN123

Just to pile on, after car overheated at Thunderhill, I put in 3/4 of a tank of 100. To be honest, it was because the 91 pumps were occupied. Anyway, in the next session the car did not feel any faster and end-of-straights speeds were not faster. And the car overheated again. So 100% agree that higher octane gas isn't helping anything.

glass slipper

There is no correlation between octane rating and flame speed of the fuel...please stop spreading this "old wives tale".

I live in Europe (Spain), the best I've found at the pump is 98 which is more like 92 if the (R+M)/2 method was used here. Where are you finding 102 octane gasoline?

red2012

Not according to this site.
https://mn.gov/commerce/weights-and-...ctaneFacts.pdf