Regular vs Premium Gasoline

[FaaWrenchBndr]

I got over the need for speed years ago. My normal driving is in town, no load, 5-7000 miles a year. 87 works fine for me. I only fill up every 3-5 weeks. I am going to the Talladega race in Oct, that will be my first road trip in the PB. 200 miles each way. I think I will run 87 on the way out and 93 on the way back home. The elevation difference is 280', so it should be similar conditions both ways.

Will I see a mileage difference?

Well, it’s actually said to take a couple tanks to everything the cycle through in the engine to adjust to the different octane. I’m not sure how much validity is in that statement.

So you might Actually see nothing. I can see my normal commuting. I saw a 2 mpg gain when I changed and started running 91-93. ‘24 Powerboost

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[dochawk]

I like your idea but what's the numbers on this?

An F-150 leaves Denver headed due west at 65MPH. Meanwhile, a Silverado . . .

?

That might sound disrespectful to grandpas,

nah, it's the grandmas that drive like lunatics!

Are you saying that my motor will continue to add timing up to an effective 96 Octane and up to 20% ethanol, during the very hot summer months?

From a bunch of reading, it seems that up to 98 could matter for Ford.

Since it's not in this thread, I'll note that when a car mag ran tests with monitors on the systems on an ecoboost, that boost went up by almost two pounds on 93 instead of 87.

But if you're not using a heavy throttle (whether acceleration, speed, or towing), it's not going to run the boost that high anyway.

A modern engine, including ecoboost and powerboost, is *constantly* watching for hints of knocking. This is how it senses the octane, and judges what it can do with timing and boost.

 

[Natetroknot]

I pay a premium at the pump for 91 non ethanol for my 3.5 ecoboost. I usually lock out 9/10th gears, drive on the spirited side in normal mode and average 21.5mpg. 3.31 rear end.

 

[Suns_PSD]

An F-150 leaves Denver headed due west at 65MPH. Meanwhile, a Silverado . . .

?



nah, it's the grandmas that drive like lunatics!




From a bunch of reading, it seems that up to 98 could matter for Ford.

Since it's not in this thread, I'll note that when a car mag ran tests with monitors on the systems on an ecoboost, that boost went up by almost two pounds on 93 instead of 87.

But if you're not using a heavy throttle (whether acceleration, speed, or towing), it's not going to run the boost that high anyway.

A modern engine, including ecoboost and powerboost, is *constantly* watching for hints of knocking. This is how it senses the octane, and judges what it can do with timing and boost.

I've been adding a solid splash of E85 to my 93 Octane for a calculated 95 octane, and in a TX summer it clearly runs stronger, picks up boost easier, doesn't do all of that snap/ crackle/ pop that you hear from a cooling motor on our 106' days.

I'd really like to know how high I can go and what happens if I go past that?

So far, I'm seeing no drop in economy and in fact, maybe a bit of an increase.

The power is notable. When I added these oversized 70# tires it really slowed the truck down, but with the added E-85, it feels like it has stock sized tires again.

What do I look for in the Torque engine monitor app to see if I'm getting all of the timing advance I can?

PS. I do have a tune so it might reach max timing at a lower octane number when compared to stock.

 

[dochawk]

I rather suspect that the limiting factor is the soft parts between the tank and combustion; that is where alcohol used to be a problem.

I'm actually kind of surprised to see a company retreating from alcohol compatibility on a vehicle that they previously sold with it.

 

[HammaMan]

I rather suspect that the limiting factor is the soft parts between the tank and combustion; that is where alcohol used to be a problem.

I'm actually kind of surprised to see a company retreating from alcohol compatibility on a vehicle that they previously sold with it.

I'm not really surprised by it. With the high pressure injection it's possible for fuel to get into the oil. Ford may have found signs that the high ethanol content was causing issues with the oil. E85 is also really bad in engines that do lots of short trips. It will cause the oil to sludge.

 

[dochawk]

E85 is also really bad in engines that do lots of short trips. It will cause the oil to sludge.

Oh, if you want oil to sludge . . . I didn't do something quite right, probably the gasket, when I replaced the intake manifold on my '98 mustang. After a 3 mile drive, my oil was already that toothpaste-like sludge. (Hopefully, now that the temperature has dropped enough to work on cars outside in the morning, I can drop the tank on my '97 Eldorado Touring Coupe and replace the fuel pump, so that I can get it out of the way to get the mustang in the shade to reinstall it. (at least I used cheap oil for the test run!)

 

[Calson]

The engine computer reacts to the octane of the gasoline in real time by sensing engine knock and retarding the spark. This has been true for the past 20 years.

Octane is a rating relating to pre-ignition and nothing more for automobiles. Higher octane rated fuel allows for its use in higher compression engines that can produce more power.

It is not an arithmetic measure and putting 5 gallons of 87 octane and 5 gallons of 93 octane in the fuel tank does not result in a 90 octance fuel mixture but rather something closer to 91-91 octane. Think about the octane booster products and how few fluid ounces need to be added to the fuel tank.

 

[Eskram]

Think about the octane booster products and how few fluid ounces need to be added to the fuel tank.

Most off-the-shelf 'octane boosters' only raise octane by a few tenths of a point - not full points. Be careful what you're buying, and what the results will actually be.

 

[Csu87]

I’m curious as to how that works. Crap gas limiting boost pressure. Shift point magic? There must be some serious spark/valve timing jiujitsu going on. Impressive

as with all stock boosted vehicles, the factory tune leaves plenty of headroom. they have safety factors to account for.

no company is going to give a vehicle with a warranty a tune that is pushing the limits. that is just begging to lose money.

 

[Samson16]

as with all stock boosted vehicles, the factory tune leaves plenty of headroom. they have safety factors to account for.

no company is going to give a vehicle with a warranty a tune that is pushing the limits. that is just begging to lose money.

I understand that part. I have difficulty understanding how they squeeze more power out of low octane fuel without early detonation.

 

[SilverPigeon]

I understand that part. I have difficulty understanding how they squeeze more power out of low octane fuel without early detonation.

x 2. I run 98RON (~your 93), not for economy gain (minimal), not for increased power from timing advance (minimal) but for the maximum insurance against detonation. This will probably never happen with your 87 (our 91): I must assume that if the knock sensors are worked too hard trying to retard timing, that, because a camshaft has a finite profile, at some point there is a lower limit to retardation, and that once this is reached, either the engine blows or preferably goes into limp mode with a MIL.

I just want to make sure I'm staying well out of the weeds on this (admittedly small) risk, but my truck cost me more than I'm prepared to gamble with, when the relatively small and constant trickle of fuel bill price is easy enough to manage.

 

[Samson16]

x 2. I run 98RON (~your 93), not for economy gain (minimal), not for increased power from timing advance (minimal) but for the maximum insurance against detonation. This will probably never happen with your 87 (our 91): I must assume that if the knock sensors are worked too hard trying to retard timing, that, because a camshaft has a finite profile, at some point there is a lower limit to retardation, and that once this is reached, either the engine blows or preferably goes into limp mode with a MIL.

I just want to make sure I'm staying well out of the weeds on this (admittedly small) risk, but my truck cost me more than I'm prepared to gamble with, when the relatively small and constant trickle of fuel bill price is easy enough to manage.

You have the coolest truck in Australia. I'm sure of it!

Building on your statement, how do they overcome the detonation issue with an "87-Tune"? Ford has built in tables that allow for 87 octane use, but those tables struggle to maintain power levels at best.

 

[SilverPigeon]

You have the coolest truck in Australia. I'm sure of it!

I don't know man, the 350 KR Tremor boys might disagree, but it's certainly unique: almost every module "tuned" (read "mucked with") except for the PCM ?

Building on your statement, how do they overcome the detonation issue with an "87-Tune"? Ford has built in tables that allow for 87 octane use, but those tables struggle to maintain power levels at best.

I'm in the same boat as you, I don't understand how it's possible ?‍ The only thing I can think of is that they advance timing to the point of forever running up against the knock sensors' thresholds; I'm betting the Ford tables retard earlier than they "must", for that knock insurance. It's the only thing that makes sense to me at the moment, but it's just a guess.

 

[Samson16]

running up against the knock sensors' thresholds

Copy that. Playing the ecoBoom! game of chicken. No thanks. 93 and no tune for my boring little PB.

No tune for now that is...

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