87 vs 93

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Encore
#21
Thanks Jeff. Appreciate the response. I'll use 91 for awhile and check the results.
Interesting read here on using premium fuel in our engine during hot weather... 2011 cruze uses same 1.4T LUV engine as the 138HP buick encore....

The Ultimate Hot Weather MPG Test - Regular vs. Premium - 2011 Chevrolet Cruze LTZ Long-Term Road Test

You can check out the cruze talk forum at cruzeforums.com for more info on running different octane fuel in the generation of cruze that comes with the same motor as our encore.

jeff
 

crakkus

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#22
I love that link. It basically proves there is no difference. He spent $645 on regular and $648 on premium. You might get more airmiles buying the premium fuel. But honestly, there is no other data, such as driving style, city vs highway, off road/on road, uphill vs downhill.

This thread is hilarious. Do not waste your money on higher octane for this engine. The encore engines are not 300+hp.

You either have power or fuel economy never both. These are designed for fuel economy. If you want power, get a performance vehicle.

If you want a "smoother ride" as some people claim from "fuel octane", remove the shitty OEM air filter with a higher CFM air flow, remove the tumblers from the intake manifold. After that, you wont be starving your engine of air and the ride will be much smoother. [I actually did this and noticed an immediate difference in smoothness of the ride].
 
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Encore
#23
I love that link. It basically proves there is no difference. He spent $645 on regular and $648 on premium. .
No difference? Really? He spent more on premium because he logged more miles on the premium. It actually cost him less per mile to run premium. So using the premium "paid for itself" with improved mpg. And the vehicle ran better.. Per the article from edmunds referenced above :

"...the hot weather led to a very noticeable lack of drive-away power and sub-par highway fuel economy. Subsequent discussions with GM powertrain bigwigs and our own Jay Kavanagh revealed that small turbo engines are especially octane sensitive, which means their computers may agressively dial back the engine calibration in order to ward off knock in high load situations or in very hot weather."

jeff
 

crakkus

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#24
I am not saying the test is pointless, but negligible from his testing methods. He only achieved an extra 0.037% miles with $3 more on premium gas. We do not know his driving habits, locations, temperatures of environment. All which affect fuel usage. Notice how he is 10 less gallon on the premium. I imagine if the regular gas and premium gallons matched he would be spending more on premium fuel for no difference.

There are to many random factors in his research that disprove his accuracy. Its a viable study, it just needs to be conducted properly.

Also, any car in hot weather will run poorly. The air molecules are too hot before they enter the chamber, therefore you are unable to get more air from the turbo to make the proper air/fuel mixture and some knock may ensue (very tiny amount). This uneven mixture causes the fuel to burn in uneven pockets rather than uniform bursts. This is when the car adjusts its air/fuel levels. Octane levels are "the resistance to burn". Again, its a gimmick. If you are not putting in 30 PSI at WOT, to match the octane, I wouldn't bother.

The Buick manual says, "Use only unleaded gasoline rated 87 octane or higher in your vehicle. Do not use gasoline with an octane rating lower as it may result in vehicle damage and lower fuel economy. " You don't see vipers, evolution, or porches asking for 87 octane.

You can go higher in the Buick, but its pointless.
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Encore
#25
The cars don't read the octane and they don't choose which map to use for the ignition timing. Read the whole thing to really understand what the ECM is doing and why.

This is how the Newer GM cars work...

There are indeed 2 ignition timing maps... High and low octane. But the ecu always uses the high octane map no matter what, until pre-detonation / pre-ignition / engine knock is detected by the knock sensors. The more degrees of knock is detected the more the ignition timing is pulled by referencing the low octane map. For example,. If 3 degrees of KR are detected, while the high octane map is asking for 20 degrees of timing and the low octane map has 16 degrees for that spot,. The ECM will command the ignition timing to be between what the 2 maps are asking for. So it will command 18 degrees timing.
If the sensors pick up 6 degrees of knock, then the ecm will use 100% of what the low octane map has for that spot in rpm / engine load / manifold intake pressure etc...
And if there was a no knock detected when using the cheapest gasoline, the car will use 100% of the ignition command in the high octane map. It's sort of a urgency calculation by the ECM.

If at full throttle the knock sensors do not pick up any knock with the cheapest gasoline you're wasting money on the good stuff.

If you actually hear with your ears the knocking/pinging, that is when severe damage is occurring. So we have knock sensors that pick up the smallest amount of knock so the engine doesn't get demaged.

You need a live scanner to see if there is engine knock with the gasoline you're using.

Things that cause knock are... Heat, not enough fuel, hot spots in the cylinder, too much timing, hot air, low rpm and higher than normal load on the engine.

So turbos and superchargers make heat. Same for higher compression ratios.

Higher octane is ONLY a resistor to pre-detonation. It does not burn cleaner nor does it give more power unless the engine is knocking and the ECM is retarding the timing giving you less power,. Cause less timing = less power.
Take a look here on adaptive algorithm used that can put you into the low octane map all the time for the 1.4 Turbo LUV motor that is currently the base engine on the Encore....

Trifecta Tuned last night -- WOW - Page 11

Out of curiousity - and since the 1.4 turbo came out of opel in europe - I decided to look at how they recommend octane for this motor in europe. The opel mokka manual can be found here :

https://www.opel.ie/content/dam/ope...okka_kta-2749_5-en_eu_my16_ed0815_9_en_gb.pdf

Whereas the u.s. owners manual only lists a minimum octane -> On page 214 of the Opel Mokka manual it states a recommended, minimum and maximum octane for the 1.4 turbo LUV motor... The values are in RON vs AKI (u.s.a.) - they list 95 recommended with min of 91 and max of 98... In U.S AKI octane rating (RON + MON/2) - this roughly converts to

Minimum Octane : 87 octane
Maximum Octane : 93 octane
Recommended Octane : 90 Octane

* these are their typical octanes for their grades of fuel - "normal", "euro super" and "super plus"

These numbers are consistent with what is recommended in the u.s. owners manual - minimum of 87 octane....

So I could run mid grade fuel with 89 octane here in North America and be a little below what is recommended in europe for this motor...

If you look at the cruze forum - this is consistent with what many report along with with real world measurement by data logging knock events - mid grade fuel works well in winter temps - in moderately high to high temps - some switch to premium to maintain good power and mpg....

And as zeroboostbuick stated - as long as the octane is sufficient - all is well and going above that won't buy you anything. With the encore motor every indication is that this "line" is above 87 octane and a more optimal amount is closer to 90 octane...

I have several costco gas stations in my area and they only carry regular 87 and premium 92 octane - with no mid grade 89 octane fuel. So I will fuel with 92 octane from costco whenever I can to save some $$ (cheaper than mid-grade fuel elsewhere). When on the road - my preference will be to fuel with chevron premium in summer and chevron "plus" 89 octane in winter.

jeff

p.s. My background is 35 years experience as electrical engineer... So I usually go into way too much detail most of the time - just ask my wife or my daughter who don't see this as a positive trait!!! they usually just say "oh gawd, not again", roll their eyes and walk away... :)
 
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stoopid

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#26
I actually didn't know how the low octane map was triggered, always wondered too. My assumption was that there was a sensor, but it makes sense that would be a rather complicated (and expensive) device. GM's strategy is a clever and cost effective workaround that effectively accomplishes what an expensive sensor would.
 
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#27
I actually didn't know how the low octane map was triggered, always wondered too. My assumption was that there was a sensor, but it makes sense that would be a rather complicated (and expensive) device. GM's strategy is a clever and cost effective workaround that effectively accomplishes what an expensive sensor would.

The Flex Fuel cars have a sensor that reads the alcohol % content of the gasoline to adjust the injector pulse width, because the more alcohol in the gasoline the more fuel must be burned to achieve the correct air fuel ratio.

But otherwise like you said, there is no sensor that reads the octane rating of the gasoline.
 

aerogel

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#28
I have a 2018 Encore with the 138HP engine. I read this thread the other day and decided i'd give the 91 octane a try on my next fill up. I tried 87 when I first got it and didn't like the way it felt. I've been using 89 octane and it seemed better than 87 but still not quite up to par. So far on 91, the engine feels really responsive. I don't know if its my imagination so i'll stick with 91 for a few more tanks to see if my feelings stay the same.
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Encore
#29
I have a 2018 Encore with the 138HP engine. I read this thread the other day and decided i'd give the 91 octane a try on my next fill up. I tried 87 when I first got it and didn't like the way it felt. I've been using 89 octane and it seemed better than 87 but still not quite up to par. So far on 91, the engine feels really responsive. I don't know if its my imagination so i'll stick with 91 for a few more tanks to see if my feelings stay the same.
To put the above into the right perspective... Where do you live and what are temperatures where you live right now? What brand of fuel?

thanks,
jeff
 
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Encore
#31
Oh I forgot that part lol...and its what really caught my eye when I saw this article. I'm in Phoenix, of course very hot temps.
Yikes. Yeah - I checked the weather there last week to see how bad you guys were getting hit by the heat wave - I think I remember 114 degrees? Double yikes...

Yeah - I don't think it's your imagination. Premium - "just say yes"...

To tie it in to my previous post - europe recommends 90 octane - but their average ambient temps in europe are much lower than those in phoenix. Given this, bumping in a little more octane and stepping up to premium fuel seems like a reasonable step to avoid pre-detonation and keep performance and mpg up.

jeff
 
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aerogel

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#32
Yikes. Yeah - I checked the weather there last week to see how bad you guys were getting hit by the heat wave - I think I remember 114 degrees? Double yikes...

Yeah - I don't think it's your imagination. Premium - "just say yes"...

To tie it in to my previous post - europe recommends 90 octane - but their average ambient temps in europe are much lower than those in phoenix. Given this, bumping in a little more octane and stepping up to premium fuel seems like a reasonable step to avoid pre-detonation and keep performance and mpg up.

jeff
Yeah, is was really hot last weekend but we had some storms blow through and now the temp is a reasonable 95 degrees :)
I'm going on a long drive later in the week on the interstate with inclines so I'm excited to see how it performs on the trip.

While I was using 89 octane it just seemed like when I asked for extra power the engine felt bogged down. I guess that may have been knocking? The feeling was frustrating. I haven't felt that so far with 91 octane.
______________________________
 
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2018 Regal Sportback - 2010 Yamaha R6 (track bike) Past cars: 92 LeSabre, 98 Regal, 02 GrandPrixGT
#33
Inside the gas door of the newer Volkswagen golf with the 1.8 turbo engine says to use 87 AKI octane or the equivalent of 91 RON octane.

It's all about how the engine was designed with what fuel the designers had in mind.

Best thing to do is buy a scanner (not a code reader) and see if the engine's knock sensors are picking up any pre-detonation. If you have knock (pre-detonation) with 87 octane and no knock with 91 then obviously 91 is the logical choice. But if you don't have any (or less than 3 degrees) knock on 87 at full throttle, you will not gain anything by using higher octane.
 

crakkus

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#34
Take a look here on adaptive algorithm used that can put you into the low octane map all the time for the 1.4 Turbo LUV motor that is currently the base engine on the Encore....

Trifecta Tuned last night -- WOW - Page 11

Out of curiousity - and since the 1.4 turbo came out of opel in europe - I decided to look at how they recommend octane for this motor in europe. The opel mokka manual can be found here :

https://www.opel.ie/content/dam/ope...okka_kta-2749_5-en_eu_my16_ed0815_9_en_gb.pdf

Whereas the u.s. owners manual only lists a minimum octane -> On page 214 of the Opel Mokka manual it states a recommended, minimum and maximum octane for the 1.4 turbo LUV motor... The values are in RON vs AKI (u.s.a.) - they list 95 recommended with min of 91 and max of 98... In U.S AKI octane rating (RON + MON/2) - this roughly converts to

Minimum Octane : 87 octane
Maximum Octane : 93 octane
Recommended Octane : 90 Octane

* these are their typical octanes for their grades of fuel - "normal", "euro super" and "super plus"

These numbers are consistent with what is recommended in the u.s. owners manual - minimum of 87 octane....

So I could run mid grade fuel with 89 octane here in North America and be a little below what is recommended in europe for this motor...

If you look at the cruze forum - this is consistent with what many report along with with real world measurement by data logging knock events - mid grade fuel works well in winter temps - in moderately high to high temps - some switch to premium to maintain good power and mpg....

And as zeroboostbuick stated - as long as the octane is sufficient - all is well and going above that won't buy you anything. With the encore motor every indication is that this "line" is above 87 octane and a more optimal amount is closer to 90 octane...

I have several costco gas stations in my area and they only carry regular 87 and premium 92 octane - with no mid grade 89 octane fuel. So I will fuel with 92 octane from costco whenever I can to save some $$ (cheaper than mid-grade fuel elsewhere). When on the road - my preference will be to fuel with chevron premium in summer and chevron "plus" 89 octane in winter.

jeff

p.s. My background is 35 years experience as electrical engineer... So I usually go into way too much detail most of the time - just ask my wife or my daughter who don't see this as a positive trait!!! they usually just say "oh gawd, not again", roll their eyes and walk away... :)
I agree with you on the different maps. I am just saying to be weary. I have yet to see some major research paper on the difference of octane fuels and they power/mileage output for different types of engines. Sure they say 90 octane is recommended...but why? until I see some decent research that says otherwise Ill stick with 97 octane.
 
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#35
For the past five fill ups, I have been using E15, which according to the gap pump sticker shows 88 octane. So far, Ive not noticed a decrease in MPG noticeable and not really a seat of the pants feeling either...
 

adamcar

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#36
For the past five fill ups, I have been using E15, which according to the gap pump sticker shows 88 octane. So far, Ive not noticed a decrease in MPG noticeable and not really a seat of the pants feeling either...
Most all gas is E10 now anyway, so E15 is not going to make much of a difference at all.
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#38
2017 Encore Premium AWD with the LE2 153 hp engine... Filled up at little more than half a tank of 87 with 93 Friday. Drove 4 hours down and 4 hours back from NC to VA right at 400 miles round trip. Relatively flat ground. A/C on Eco mode the whole time. Averaged about 50 mph but mostly 55-65 mph on highways with slow downs for little towns and in Raleigh. Driver info computer said 34.3 mpg for the trip. Refillled pretty much the whole tank with 93 this evening. Don't know if my trip tank had enough 93 octane to change any parameters or not, but extremely happy with the mpg considering awd is at least 1-2 mpg penalty over the front drive.
 
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Buick
#39

They even use a 2013 Chevy Cruze, which uses our same engine.

Hopefully this will shed some light on this issue. The video at least does a better study then this dude driving around without any test equipment. Even the US FTC says to run regular vs premium fuel.

Dont feel like watching?
Result = regular has the same performance as premium.

don't waste money on premium.
 

Skylarkin'

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#40
Even for a non-Encore driver like me, this is an intriguing thread. Octane levels here are 87, 89 and 93. The first thing drivers should do before changing octane levels is read the owner's manual to learn what the manufacturer recommends for the engine.

GM recommends premium for my current and previous cars, even though the previous car's engine was naturally aspirated (non-turbocharged). I ran 87 through once in the old car to save $ but heard the engine knock so I never used regular again in it. When prices would spike, I'd switch from premium to mid-grade. With the Verano, I would never run regular in it and will change to mid-grade only if there's a major price increase.

My partner owns a 2014 Encore and he's filled it with premium infrequently. He thinks he got slightly better MPGs using it but not much else. His commute is 95% interstate anyway so he tends average mid-30s for mileage. To echo one of Crakkus' points, my partner didn't buy the Encore to drag race in it; he chose it for the MPGs, the cargo space and he liked the (at the time) high-end tech and semi-lux trappings.

So far, the posts claiming improved MPGs and engine smoothness outnumber the posts claiming premium fuel is a waste of money. It's all a tiny sample size and some of the results posted are subjective but I find them interesting anyway.

As others have pointed out, "your mileage may vary" but it was telling that the Edmunds link from 2011 focused on how premium fuel can improve hot-weather driving in the American Southwest while the ~2013 video was shot in Ontario, Canada, which rarely sees triple-digit temps.

After reading the documents linked above, I found them more credible than the video, which seemed heavily edited to prove their point. I had hoped to see the test results displayed at the end to compare them.
 
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