Premium Gas in UZJ100 V-8 motors

ELLTEE

ELLTEE

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I saw one poster (matt?) recently say he has always used regular unleaded in his V-8 without pinging or apparent damage.

Does anybody else use less than premium unleaded in their V-8? And what "octane" is premium in other parts of the country?

Dallas' smog problems require all of the federal DOE fuel additives that cut back on octane and gas milage. When I travel out of Texas, my milage gets better with every tank!

LT
 
uzj100

uzj100

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I have a '99 with 71k miles. I rotate through the octane levels here in NC, 87, 89, 91. Never ever any pinging or knocking and I drive the v8 very hard. The only mod to the engine is a k&n filter.

Later,

Andrew :D
 
80and100cruisers

80and100cruisers

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Yes, I use regular, 87 octane, 95% of the time and have had no problems from running it. The car has 59,000 miles and no engine mods. The 87, 89, 91 looks right for Houston ratings. I think I have seen a 93 super premium somewhere. I also drive my engine hard. :D


-Matt
 
firetruck41

firetruck41

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Most newer engines that require premium have knock sensors that adjust fuel timing depending on conditions, including lower octane. From what I understand this should prevent damage but means the engine won't be at it's full potential.
 
cruiserdan

cruiserdan

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In some cases (forced induction for example) the computer can not pull the lead out fast enough at a critical time to prevent possible engine damage. Exercise caution accordingly.........
 
C

cruiser99

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I used to run regular on my 99 all the time. Never had any problems. The mileage may have been lest then optimum. I start running premium after I installed 35” tires. A lame attempt to get some mileage back.
Doron.
 
U

Underdog

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Yes all gasoline is now unleaded but octane varies. &nbsp:Down here in Texas its generally 87, 89, 93. If you travel north into Okie country 91 seems to be the norm for premium/super and as you head over to Colorado the octane continues to decrease as the elevation increases.
 
Keep

Keep

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as you head over to Colorado the octane continues to decrease as the elevation increases.

Why is that?

A few years ago outside of Denver I rented a little Rodeo, they filled with 85 octane before I hit the road. That thing knocked like mad everytime I climbed a hill.
 
Photoman

Photoman

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The hotter the temperature the higher the octane needed. The drier the air the higher the octane needed. $.02 worth.
Bill
 
Beowulf

Beowulf

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Bill,

Far be it from me to challenge you as I know absolutely nothing about this subject. However, I am curious.

We live at a high altitude (over 5,000') and our fuel is of the "lower octane" varieties. I think 87/89/91 is typical.

>> The hotter the temperature the higher the octane needed. <<

Our spring/summer temps are frequently in the 90's and sometimes over 100 in July/Aug.

>> The drier the air the higher the octane needed. <<

Summer humidity is frequently under 10% and almost always under 20%. A 50% humidity day is very rare. I lived in Houston where anything under 90% was considered "dry air."

Could it be that the air up here is "thinner", producing less HP, and less heat during burning? Therefore needing less octane to avoid detonation?

I really don't know... this is a question.
-B-
 
Beowulf

Beowulf

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Somewhere in the foothills...
In high-altitude areas such as the Rocky Mountain Region of the U.S., the (R+M)/2 number may be lower by one or two numbers.

That article just confused me because of the inconsistancies. Why do they reduce the octane in high-altitude areas and then tell us that temp and low humidity increases the need for higher octane.

I think a federal investigation is in order. -H-, are you up to it? Think class action lawsuit. We're paying for octane that we're not getting and, according to the Chevron article, we need the higher octane! You could be a billionaire RSN.

:D

-B-
 
SteveH

SteveH

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My v10 Ford owner's manual suggests you not use 85 octane gas even at higher elevations where it is typically sold as 'regular'. I've never seen a manual make that distinction. I did anyway, and while towing up a long grade at elevation this past weekend, I got the faintest tinkle of spark knock. I assume the computer may not be able to adjust out the knock with this gas. Having said that, I plan to continue buying 85 octane as usual.
 

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