Mixing regular and premium gas

[dn325ci]

no their baseline is premium stock, not 87. I have not seen a 87 dyno plot.

Are you saying the "stock" curve here is run on premium fuel? I looked and could not find a citation about what fuel was used, but if I were a company marketing tuning I would want to show the largest gains, which would have obviously been versus the allowable 87.

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[Ozarkbeard]

I recently switched to Shell high octane and am seeing worse mpg.

High octane gas in a Hybrid is a complete waste of money. TopTier gas, OTOH, is not. https://www.toptiergas.com/

The "pure gas" ethanol-free station listing posted by ripperAZ is not very accurate at all, at least in Arkansas. There are tons more stations here than were on that list. And many of them sell ethanol-free "real gas" in regular, mid and premium grades.

 

[Johnny maverick]

I've driven my mav for 36k so far and 99% of that was on 93 octane. I just recently started to run 87 just to see. It was like I cut its nuts off. You can definitely feel the power loss and fuel economy drop. I ran my tank dry ( 2 miles to empty) and filled back up with 93. Couple of hard throttle runs to help it relearn spark curve and injection pulse width and its back to its peppy self. Anybody arguing it does nothing is oblivious to modern turbo engines. I agree that you won't see any difference in a hybrid Atkinson type engine.

 

[Carlitos_92]

...if I were a company marketing tuning I would want to show the largest gains, which would have obviously been versus the allowable 87.

That would be an irrelevant and possibly sneaky comparison. If owners can already get more power on the stock tune with 91, why would the baseline for comparison be 87? It's not like you're locked out of 91 without a tune, so the most straightforward and ethical comparison a company could show is apples-to-apples with the same octane rating.

Even if they were marketing a tune for 100+ octane racing fuel, they would still start with premium fuel as a baseline.

 

[colinl]

Are you saying the "stock" curve here is run on premium fuel? I looked and could not find a citation about what fuel was used, but if I were a company marketing tuning I would want to show the largest gains, which would have obviously been versus the allowable 87.

yes. the dyno chart compares the stock ECU map vs their tune, and they definitely use premium on the stock run because the truck specifically says premium for maximum performance.

 

[dn325ci]

yes. the dyno chart compares the stock ECU map vs their tune, and they definitely use premium on the stock run because the truck specifically says premium for maximum performance.

Sure, the owners manual says premium for best performance, but it also makes clear that 87 is acceptable, and the fuel filler door (for the 90% that don't seem to read the manual) says 87.

I'm asking do you know for sure this curve is based on premium octane? If so, how do you know that? Could be, but I don't see it in the notes.

 

[dochawk]

that is false. the knock sensor is a microphone and it's listening for detonation and pre-ignition and adjusting after they happen.

as I said, sensors for pre-knock.

 

[colinl]

as I said, sensors for pre-knock.

pre-knock does not exist.

pre-ignition is when the fuel air mix ignites before the spark arrives.

detonation is when it explodes instead of fully burning after spark.

those are the abnormal combustion events that the knock sensor listens for and it's after it happens. not "pre'.

are we done? you have a hybrid. you're arguing with me just because you enjoy being wrong.

 

[dochawk]

We were done when you rejected the words commonly used in these discussions for the last couple of decades, long before ecoboost was conceived . . .

I own multiple north star Cadillacs, which have been playing the octane and knock game since the 1993 model year.

I can blow up a grade on 87 in them without knocking. I can do it faster on the recommended 91, as it doesn’t adjust timing when detecting what we’ve called “pre-knock” for a couple of decades now.

 

[Johnny maverick]

I never heard the term pre knock before and I've only been doing this for 40+ years. I've heard the term "knock" (which is pre ignition)before but not pre knock.

 

[tciotti2003]

Question. What states have 93 octane? Here in Az only 91. Thanks in advance

 

[Carlitos_92]

Question. What states have 93 octane? Here in Az only 91. Thanks in advance

https://find93.com/

 

[Camdak]

Question. What states have 93 octane? Here in Az only 91. Thanks in advance

Do you have 94 octane in the U.S.? Chevron in Canada has it but the only one, otherwise it’s 87, 89, 91 anywhere else.

 

[Blue_Max]

Do you have 94 octane in the U.S.? Chevron in Canada has it but the only one, otherwise it’s 87, 89, 91 anywhere else.

I used to see 94 at Sunoco, but I can't remember the last time I saw a Sunoco.

 

[tciotti2003]

Do you have 94 octane in the U.S.? Chevron in Canada has it but the only one, otherwise it’s 87, 89, 91 anywhere else.

Thanks. No 94 octane. But all I use is chevron...tier 1 gas

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