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Discussion Starter · #1 ·
Hello,

I was filling up yesterday and noticed a new sticker on the pump that stated 91 octane. Up until now i've used 76 gas because of many people stating it's the better gas for a Vette. So what gives now 91? I wonder if anybody else in southern calif. has noticed this, Greg. PS.what's next 89 super?????
 

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Yeah, I noticed that yesterday filling up at a Chevron in San Jose, CA. I asked the guy at the desk and he didn't even know it had changed.

I didn't hear anything on the news either. Hummm, interesting. Will have to see if I run across any articles or anything.
 

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Discussion Starter · #3 ·
First,they rip us off with high gas prices and now this!!!!!G
 

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Torched,

I live in Claremont, CA here in the LA suburbs and I noticed the same thing. I still think Union76 is the best gas out there. I used a full tank of the 91 octane and had no problems with pinging under any conditions. On the high performance motorcycle sites I frequent, there has been extensive discussion of which gas is best to use and the general consensus of the well informed is that the higher octane gases ignite more slowly preventing pre-detonation but they also generat less power (for exactly the same reason.) Therefore, you should use the lowest octane gas that your car will tolerate if you want the best performance. I have a 2000 Suzuki Hayabusa which is an ultra high performance motorcycle with an 11:0 to 1 compression ratio. I use Union76 89 octane and the bike runs better than with the 92 octane (however I'm not recommending 89 octane for the Z06.) I know Chevy recommends 93 octane, but 91 octane that doesn't ping could be a blessing in disguise in that you will get more punch from each cylinder stroke than with a higher octane gas. What do the rest of you guys think?

EZ
 

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GM states that only three of their engines require 93 octane fuel.

The three engines are:
  • Chevrolet LS1
  • Chevrolet LS6
  • Cadillac Northstar
 

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I'm in NorCal and noticed the change to 91 octane as well. I use Chevron Supreme and all the stations around have just dropped their octane rating from 92 to 91. I took on a tankful in my bike ('00 ZX-9R) with 12.2: C/R and had no problems. Also, filled up my LT4 (10.8:1) and it still runs fine.

Here in San Jose, the price per gallon has finally come down to the under $2 range which is right about the same time I noticed the lower octane ratings on the pump.
 

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Well, if you don't mind a slightly crappier fuel, Costco's that have gas stations are selling 92 for around $1.50/gallon (last time I filled up it was $1.529).

I figure if I save $0.40/gallon which means like $8/tank I can save a shit load of cash. I'll put up with the slightly crappier fuel and just not race the car (shes a daily driver).

If I was racing it, I'd definitely put some better stuff in though.
 
G

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On 2001-07-23 11:57, Torched spewed forth this drivel:
Hello,

I was filling up yesterday and noticed a new sticker on the pump that stated 91 octane. Up until now i've used 76 gas because of many people stating it's the better gas for a Vette. So what gives now 91? I wonder if anybody else in southern calif. has noticed this, Greg. PS.what's next 89 super?????
This was reported a few weeks back, though not very well.

Published on July 13, 2001, San Jose Mercury News (CA)

GASOLINE OCTANE RATING DROPS WITH NEW ADDITIVES

Gas prices aren't the only item falling at your local station. The octane rating is also dropping. For years, there have been three levels of gas -- regular 87 octane, mid-grade 89 and premium at 92. But on Aug. 1, all premium or super unleaded gas in California will change to 91 octane, and at
some stations mid-grade will fall to 88.5.Officials say phasing out MTBE, a gas additive that helps fuel burn cleaner, and adding ethanol or another additive is leading to a slightly lower octane level"
 

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Now don't get me wrong, I agree that for top performance you should use the highest octane rating... but I thought this was interesting:

Here's what Sam Winegarden, chief engineer for GM Powertrain's small block team, said while being interviewed by the NCM:

(NCM) Will this version of the LS6 still operate fine with regular fuel? Is premium fuel still recommended?

(Sam) Yes, premium is still recommended and yes, it operates just fine with regular - the ESC [Electronic Spark Control] system adapts to it. There is of course a slight degradation in performance. The two areas where you'll lose a little performance is at low speed heavy load and then at top end. Pulling the spark back will reduce the torque a little. Driving around town you won't really notice. On the track yes, but around town just use a little more pedal because there's a lot there.

http://corvettemuseum.com/specs/2002/samwinegarden.shtml
 

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Went to gas up last Thursday in Valencia, CA(35 miles due north of downtown Los Angeles) Noticed the 92 octane sticker at this and other Shell stations has been replaced with a 91 sticker:-?

Texaco did the same thing:roll: No station people could explain.....

BTW, my Z's owners manual recommends 91 Octane. I've seen some reference to 93 octane mentioned in some auto mags, but then again I've seen many errors in the auto press.

Any one know if Octane boosters work. I've heard pros and cons. All I know is from personal experience.....My '93 Toyota TT Supra dynoed stock at 332rwhp at Jet Chips in Huntington Beach, CA. They were surprised as most TT Supra's were turning 310-312. I made one slight modification-2 quarts of 108 Octane Booster!! Sooooo, me thinks it works:)
 

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I plan to run 93 octane anyway using one of the following options.

Buy gas out of state. Cheaper/Better. Truck it in 55 Gal. drums.

Mix unleaded race fuel with our CA junk to bring it up to 93.

I would not use boosters, as I have heard all bad about them..

Any input or suggestions appreciated.

Thanks,

2k
 
G

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On 2001-07-24 21:07, 2k Cobra spewed forth this drivel:
I plan to run 93 octane anyway using one of the following options.

Buy gas out of state. Cheaper/Better. Truck it in 55 Gal. drums.

Mix unleaded race fuel with our CA junk to bring it up to 93.

I would not use boosters, as I have heard all bad about them..

Any input or suggestions appreciated.

Thanks,

2k

Here's a table I put out for the team on what the octane points are with mixing 92 and 100 octane

http://teamzr1.com/octane.html

This whole gas issue is only going to get worse /phpBB/images/smiles/icon_frown.gif

John
 

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or you all can move to Canada and run Chevron 94!
Actually I have not noticed any difference from running 92 to 94.
Watch those additives -ran them in a 12-1 big block -eventually caused trouble to the valves.
01 QS ZED-OH6
 

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Thanks teamzr1.

ZED, Canada is a bit far. Thanks anyway.

I have located some Sunoco Oxygenated Unleaded race gas (104 Octane) for about $ 4.40 gal. + tax. I will try to pick a drum up in my truck and give it a try this weekend.

Will keep you posted.

2k
 
G

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Keep in mind it is just not the 1 octane less, it's they are sticking some other crap in the gas now to replace the other crap that they tried to shove down our gastanks as re-formulated.

Be sure it will be poping up down the raod that the new crap is just as bad for injectors, etc.

and adding ethanol or another additive is leading to a slightly lower octane level"

John
 

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On 2001-07-23 13:15, VPRKLLR said:
GM states that only three of their engines require 93 octane fuel.

The three engines are:
  • Chevrolet LS1
  • Chevrolet LS6
  • Cadillac Northstar
Well---this is not quite accurate. What GM says is: premium fuel is *recommended*. It's a minimum of 87-octane gas that's required. C5s will run on 87, though not very well. They will experience a lot of spark retard via knock sensor input until the PCM learning ability alters the spark curve to be less aggressive and they will have a noticeable loss of performance.

I've seen two figures from GM as to the recommended octane for the LS1/6 engines: 93 and 91. Why the confusion? I'm not sure but I suspect the actual recommended number is 91 because that's what it's been in the past.

In any event, in a practical sense, even 93 octane is not enough if we are to believe some internal oil industry studies I've seen. To keep the engines out of detonation in most atmospheric conditions and under most engine duty-cycles, some performance cars require as much as 94.5 octane.


Keep in mind it is just not the 1 octane less, it's they are sticking some other crap in the gas now to replace the other crap that they tried to shove down our gastanks as re-formulated. Be sure it will be poping up down the raod that the new crap is just as bad for injectors, etc. and adding ethanol or another additive is leading to a slightly lower octane level"
John Rovner's comments are always, uh...interesting. In this case he's wrong.

The principle oxygenate component in gasoline sold in California (and most of the west coast for that matter) is still MTBE. Ethanol is not legal as a gasoline component in California, yet, but it will be soon as the phase-out of MTBE is coming.

Another fact: oxygenates like MTBE and ethanol do not decrease octane they increase it. In fact, MTBE was originally developed as a possible octane-booster replacement for tetraethyl lead. It wasn't until later (the late-70s/early-80s) when it was discovered it could reduce exhaust emissions. Ethanol increases octane and acts as an oxygenate, too.

The reason 76 (and some other oil companies, too) reduced the octane of its premium and mid-grade gasolines was mainly for two reasons 1) the oil companies on the west coast finally gave in to the pipeline companies and agreed to stop shipping both 91 and 92 octane premium unleadeds. The pipeline companies wanted just one grade of premium gas to ship. 2) the oil companies can increase gasoline output if octane is reduced slightly.

Interestingly, 91-octane premium is not, yet, nationwide. All along the eastern seaboard, 92- and even 93-octane has been common.


I have located some Sunoco Oxygenated Unleaded race gas (104 Octane) for about $ 4.40 gal. + tax. I will try to pick a drum up in my truck and give it a try this weekend.
In California there are a small number of 76 stations and even a few Cirle K's that sell 76 Competition 100 unleaded racing gas through pumps. I buy 100 unleaded from a 76 station right near my home. My understanding is you can go to to http://www.76.com to find the locations of these stations.

To keep a Z06 out of detonation in all weather conditions and under any load my guess is you need 94.5 octane which is a mix of about 2:3 76 Comp. 100 to 91-oct. pump gas
 

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Hib,

Thanks a million for the info.

I bought some Trick racing unleaded (100) to blend with the CA crap. Also found a shop that carries 104 Sunoco Oxygenated Race fuel. Will try that next at the same ratio. See what happens. Both fuels are unleaded and EPA approved. $ 4.40 a Gallon.

2k
 
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