89 over 87?

[daves87rs]

Yikes!

Both of my cars have been a bit sluggish lately. I'm really starting to think that it might have something to do with the quality of the gas around here (everyone is trying to be the cheapest price in town).

I usually run 87 octane, but put 89 in my Balt this time. And I've noticed it's a bit perkier.

I've haven't run 89 in years ( meaning by using it more often),
as the 87 usually works fine.

Might it be wise to stick with 89 octane for a while?

 

[sangyup81]

cheaper to mix 1 part 93 with 2 parts 87

if you want to try 88 octane, go with 1 part 93 for 5 parts 87

 

[beast3300]

Octane is not related to hp output unless high compression and/or timing and/or boost. What kind of car is this?

 

[Unearthed]

I swear my 4cyl Accord feels quicker with 89...but only needs 87. Probably just wishful thinking.

 

[mechtech2]

You can't simply figure the octane when mixing grades by algebra.
This is because the additives have less impact as the octane goes up.
Roughly, if one gram of additive raises the octane from 80 to 85, an additional gram will only raise it from 85 to 87, and so forth.
Diminishing returns.

If a car runs better with higher octane, your knock sensor is not being activated like before, or the car has relearned to utilize all of it's advance programming again.

 

[Trav]

89 was always regular.The first time i saw 87 was around 1989 when Sunoco had 87 economy.
This cheap swill has now become the modern over priced regular.
I always use 89 when something calls for regular.

 

[Kestas]

Really?... I remember 87 was a popularly available regular for a long time before 1989.

 

[CROWNVIC4LIFE]

I recall years ago Sunoco had something called economy regular...I think it was 86 octane...I never used it but I think that is what they had...I knew someone who once owned a Sunoco station in New Jersey on Route 4 and he said he used to dump the low octane into middle octane cause no one would ever know the difference...I would say it worked cause no one ever came back to complain.

To the OP I would just stick to the 87 octane if that is what the car calls for...I would give Gumout with Rogene or Techron a try.

 

[JustinH]

You guys do know that 89 octane is just a blend of 87 and 91, its blended right at the pump.

Gas stations get two grades of gas, regular and premium.

87 + 91 divided by 2 is?

If the car is pinging, then put a higher grade gas in it. If it isn't pinging, then keep doing what you are doing, and look to other solutions.

How is the fuel filter? Plugs and wires?

 

[iunderpressure]

We don't have 91 octane anywhere around me. We have 87, 89, and 93.

 

[lexus114]

Originally Posted By: iunderpressure
We don't have 91 octane anywhere around me. We have 87, 89, and 93.



Same here. So that means if a gas station sell`s 87,89,93 octane fuel. And you add 87-93 = 180 divide by 2 = 90 octane,right?

 

[mechtech2]

In general terms, yes.
But octane additives have less and less impact as more is added.
Let's make up numbers:
If one gram raises the octane from 80 to 87, an additional gram will only go from 87 to 89. The results are diminishing.

So adding 50/50 of 2 octane grades doe not allow simple algebra to arrive at the actual end result. Close, but no cigar.

 

[daves87rs]

Well, I guess My Balt wanted a cleaning....it's running better on 89 than it has in a while. The rest of the car is up to date, so I know it is not the plug or wires.....

It is about due for a fuel filter, but I question the impact of that. Still, it will get replaced anyways very soon...

Also, it's a 06 Cobalt 2.2 Ecotec, if that helps...

 

[MrWideTires]

We have 87, 88, 89, 91, 93, ...a few occasions 94. And the racetrack nearby with 100, 110, etc

 

[daves87rs]

Originally Posted By: MrWideTires
We have 87, 88, 89, 91, 93, ...a few occasions 94. And the racetrack nearby with 100, 110, etc

Nice!

 

[dnastrau]

Originally Posted By: Trav
89 was always regular.The first time i saw 87 was around 1989 when Sunoco had 87 economy.
This cheap swill has now become the modern over priced regular.
I always use 89 when something calls for regular.


Just to add a clarification to that: 89 was leaded regular and 87 was always unleaded regular when looking at pump octane "Research+Motor octane/2" numbers remembering back through the last 30-35 years since they started requiring the yellow and black stickers on the pumps - and switched the octane rating method to R+M/2. The Sunoco 86 "economy" unleaded and 85 unleaded out in the west (high altitude) seemed to be the only exceptions.

In the early '70's when unleaded regular was introduced we still used the straight "Research" octane scale and the Research octane of unleaded regular was 91 and leaded regular was about 93-94; premium was about 98-100 in most cases. I think Sunoco 260 was even higher. Everyone in the world still uses that scale except for the US and Canada. That's why premium in the UK is listed as 98 octane but it actually corresponds to our current 93 octane.

A good example showing how the numbers have changed and have been confused over the years can be seen with GM cars. Starting in '71 GM said virtually all of their cars were now tuned to run on "...91 octane low-lead or unleaded fuel" and did so by limiting compression ratios to 8.5:1 or lower and adding hardened exhaust valve seats. This means 87 octane in today's R+M/2 measurement. "100 octane" gas in the US in 1970 would correspond to roughly 95 or 96 octane on today's pump stickers.

 

[jhenle]

It would make very little economic sense for me to run 89 octane. Around here, 89 is priced so close to 93 that I'd likely go straight to 93 if my car wasn't running fine on 87.

(edit) sample prices from this morning:
87 $2.54
89 $2.77
93 $2.87

 

[getnpsi]

On the west coast we have the traditional 10 cent price jumps per grade

87 2.83
89 2.93
91 3.03

if you go to a brand name station that lets you use credit cards its 10 cents higher per gallon.

To the OP if you do not have audible ping you should use 87 octane and look into whats left like that fuel filter. Going to shell or chevron is considered better quality gas but any location that gets a heck of a lot of traffic is going to have fresh stock.

 

[wiswind]

More sluggish than normal......I would make sure that the fuel filter has been changed recently and maybe run some fuel system cleaner.
Also.....Air filter.
How old are the spark plugs........
I am thinking that something has changed.
If the vehicle was running fine on a given octane rating.....it should continue to do so unless something has changed.......which is why I mention the routine maintenance things.

 

[axjohn]

Hey, "gtnpsi", we're neighbors (me=91739). Which Wally World are you getting that PP for that price on closeout, and did you leave any?