jerSSey HHR

Here we go with the "embarrassment" again. As if we are offending the SS by using 87 octane fuel. And maybe people at the gas stations are taking notes if we try to use 87 octane in the SS. Maybe they are sending emails to Chevy trying to get us in trouble.

With some people, I feel like I am being shamed into using premium fuel.

The topic has thoroughly documented the 87 vs. 93 octane issue. It is now up to each owner to decide what octane fuel to use, depending on their preference, driving habits and type of roads they typically drive on. Case closed.

Clevelandhhrss

Yeah, I agree. Closed

XXL

You can't even follow the conversation when you're the one involved? Your responses seem totally disjointed with what's being discussed. I believe it's why you appear not to have absorbed any of the facts others have provided in this thread.

Clevelandhhrss

I really love that avaitar of capn picard! Its great (no sarcasm).

If you havent noticed xxl I have lost interest because I have achieved my goal of absurd mileage. No boom, no problems. I have a decent understanding of engines (much better then you seem to think cosidering your attached links). Not super duper, but decent. So I'll keep drivin it like I love it, not like I stole it. Gettin 36mpg on 87.
You can't take that away from me no matter what facts, or links, or opinions you bring up. I'm at work and have things to "engineer", since that's what they pay me for.

ColeTrickle

I have run both 87 and 91(california's premium) in the SS.

I drive 65+ miles round trip to work a day and my average speed is 39-42 mph.

When driving to and from work I usually baby the car and rarely get more than 5 pounds into boost.

Gas mileage is identical (87/91) No change at all (average around 26 city/hwy)

Performance is down a tad with 87 from the old seat of the pants o'meter.(I would guess 15-20hp)

If your looking to flog the car every day or running in high altitude or high heat 91+ would be the way to go.

For commuting why waste the extra $$ if it dosen't hurt the car?

It's an endless debate.....

Owebo

Great post. You bring up other points worth discussing, altitude and heat. A lot of people in the mid west cannot get 93 octane. They get something close to 90. The increase in altitude makes the air less dense and as such, less anti-knock chemicals (lower octane) are needed. A lot of people that travel out that way for the first time are usually surprised if they use 93,that they cannot find anting close to it. Even regular is lower than 87. With the turbo, this effect is negated under higher boosts.

Heat has the same affect on octane, only to a lesser degree because of the added heat energy and the density change from heat (100 degrees F) is not as drastic as with altitude. Drag racing with a low pressure fuel system or carb requires a step back in octane because of what you may remember as vapor lock. The gas would behave differently when heated because of the increased vapor pressure of higher octane fuels and would essentially 'boil' in the fuel lines. With our high pressure fuel systems, it is not the issue it used to be, but it will still burn slower in a less dense air charge if you re normally aspirated. With the turbo, this is negated under normal and higher boosts...

When you combine the two, a hot high altitude day, you do not want premium in your car......

GDZHHR

I don't know what "mid west" you've been in but I can get 93 octane and have been able to buy it in Missouri, Illinios, Kansas, Oklahoma and Arkansas. And have only once seen octane lower than 87 and that was at a rural station which offered five different grades(85, 87, 89, 91, 93). It's not so much the region the determines 91 or 93 but the station. Here in St. Louis, BP and Shell sell 93, most evereyone else is 91. And

Owebo

Not being from there, would I then call them the mountain regeion? Not sure. Colorado, Montana, Arizona, New Mexico.....Mainly the states higher in elevation since it is an elevation thing....The stations really have no option, it is dependent upon the wholesaler based on government guidelines.

Sorry for the confusion on my part.....

XXL

Modern Petroleum Technology - 5th edition.
Editor, G.D.Hobson.
Wiley. ISBN 0 471 262498 (1984).


Words.