Octane rating

[powerboatr]

3.5 not in heavy duty pickups, might be because those trucks are normally worked hard, with exception of the crowd that just buys a dual wheel pickup becasue its cool, which they are.!!
f250 LD maybe be a good candidate, but right now ford sells tons of 250s and 350s with the diesel over the gas burners
the 6.7 now is killer powerplant with gobs and gobs of tq...which is why the axle ratios are getting higher and still being rated to pull houses.
now days a crew cab dual real wheel truck 3.55 or 4.10 gears. few years ago the 4.30 was the king daddy for towing
3.31 or even higher for 250s
sweeeeet

 

[JExpedition07]

The owner of the marina we keep our boats at has two super duties with the 6.7 and one with gas 6.2. I have been with him multiple trips with 35' cruisers behind weighing about 15,000 pounds dry, both gas and diesel tow with no problem. He actually said he doesn't notice much difference when he switches trucks. ( the diesel is a dualy and he switches to it for cross country hauls.) but those power plants are crazy good. Back on topic though I agree that it would be strange to require premium gas in an expedition, but then again they dont as it says recommended minimum is 87.

 

[rjdelp7]

I drove Mercedes ML350s, 2003, 2006, 2009 all of the required premium fuel IT is very acceptable. If you can't afford it then you can't play with this crowd sorry. You don't have any like minded individuals here.

Ben Franklin quote: "A FOOL AND HIS MONEY ARE SOON PARTED"

 

[jeff kushner]

An interesting conversation/debate to say the least.

I don't know how many other guys here have actually built a turbo'ed engine or have rebuilt a turbocharger but I did read a few mistaken statements in the past 2 pages of discussion.

First, the 3.5 turbos only compress ambient air and stuff that compressed air into the engine. Once in the cylinder, THAT's when the fuel is injected. So any heat generated during combustion will never affect the turbochargers, ever.

Also, many people don't understand what "octane" is...it's simply a measurement of detonation resistance. Higher octane, more resistance to detonation. It is also true that many higher octane fuels burn slightly slower....and this in itself can contribute to higher gas mileage.

Finally, turbo'ed engines are much more susceptible to detonation as is the supercharged engine in my two seater car, using higher octane minimizes that from occurring. This isn't opinion, it's fact.

Compressed air absorbs more fuel so if it's compressed prior to entering the cylinder then compressed again during the compression stroke/cycle...it's got a much higher chance of detonation compared to the same spec, non-compressed charge. The EMU can adjust the timing back to accommodate low octane fuels but it's not running at peak performance then....not really hurting it but not running at it's best. On many engines, it does this by literally hearing detonation (a knock sensor affixed to the engine picks up the vibrations) occurring then backing the timing accordingly. I honestly don't know the solution Ford uses in our trucks but that's how it works.

So in a way, everyone is right...and many are wrong....but therein lies the beauty of ownership....it's your truck, do what you want!!

lol


jeff

 

[LokiWolf]

Yep...got one guy on here, thinks the Eco is a Bad Motor...then there is everybody who actually drives one. We Love it.

People keep saying that the point of the Eco is better MPG. It does have better MPG, when Output is factored in, at the Same MPG as the 5.0 based on Fuelly, the Eco Boost gets 40 More LB/FT, and has more usable power, because of how flat and steady the powerband is.

We keep hearing the 5.0 is better in the long run because of maintenance, yet I have really not heard any horror stories with the 3.5 across the board. Hell even a V8 can have it's own set of issues. Let's take the 5.4 for example and it propensity to spit spark plugs...Only time will tell. So far the EcoBoost 3.5TT has a great reputation.

Like Jeff said, lot's of FLAT UP WRONG info in this thread. If you read it on the internet, and don't actually know the science, don't repeat it.

"Better to remain silent and be thought a fool than to speak and to remove all doubt." That applies to the Forums also.

Bottom line... You can run 87. It will not hurt your 15+ Expy. You can save a little money at the Pump. If you want the best Performance, run 91+. If you don't have to pay for your own gas, definitely run 91+, why not???

 

[Flexpedition]

Ben Franklin quote: "A FOOL AND HIS MONEY ARE SOON PARTED"

Leroy Franklin quote: "SOME FOOLS NEVER HAVE MONEY CAUSE THEY RETARDED"

 

[drewactual]

uh... there is no 'extra heat' from burning higher octane. it doesn't work that way.

furthermore, these engines aren't stupid. they are highly monitored- spark advance is granted accordingly, and with a higher octane (rand count) the engine will edge forward with advance, which improves torque-translated-to-horse power.

the eco-boost is a great engine by almost all accounts. comparing it to a naturally aspirated v8 is a fools game, as the turbos cramming air easily match the air displace (volumetric efficiency) of the larger non-boosted engine... which translates simply "it doesn't push the air or add extra fuel as a catalyst to that air when it's not needed", which equals fuel savings. when you do need it, though? it's there.

 

[JExpedition07]

If it is such a fools game let's see it tow at max capacity every day for ten years like the naturally aspirated V8s then come back and see who is better off. I know a few guys with the 3.5 in 150s and they all say when you haul it sucks gas like a pig V8. If it was so proven it would be available in larger trucks. Not to completely knock it as thus far it has proven to be a great engine I am just curious because at the end of the day you are pushing the same power out of a lot less engine and it's bound to take a toll on it somewhere as time has proven over and over again.

 

[drewactual]

If it is such a fools game let's see it tow at max capacity every day for ten years like the naturally aspirated V8s then come back and see who is better off. I know a few guys with the 3.5 in 150s and they all say when you haul it sucks gas like a pig V8. If it was so proven it would be available in larger trucks. Not to completely knock it as thus far it has proven to be a great engine I am just curious because at the end of the day you are pushing the same power out of a lot less engine and it's bound to take a toll on it somewhere as time has proven over and over again.

i'd reckon affording it the opportunity to prove itself for ten years before condemning it based on preconceived notions and supposition is in order, no?

and why would a person who tows max capacity everyday for ten years straight be running a half ton with a gasser anyway? that is foolish in itself. there are machines made to do that, and they aren't half ton pickups with any configuration of engine .

 

[JExpedition07]

i'd reckon affording it the opportunity to prove itself for ten years before condemning it based on preconceived notions and supposition is in order, no?

and why would a person who tows max capacity everyday for ten years straight be running a half ton with a gasser anyway? that is foolish in itself. there are machines made to do that, and they aren't half ton pickups with any configuration of engine .

You are absolutely correct however a lot of people haul daily with 250's with gas jobs and everyone seems to think it can compete against the 6.2 motor which I disagree with in that kind of application. That is my point that if it could beat out the 6.2 long term it would be available as an option, it is however not. I guess this whole mini rant is that I think even though the ecoboost is a good engine another option would be nice as most others are offering a few configurations to the consumer.

 

[NevadaGeo]

Just a simple chime in here on this topic. Lots of back and forth on the virtues of the higher octane with little science behind the comments. Jeff lays it out with the science. I bought my 2012 F-150 with the 5.0L thinking it will be a better performing engine than the optional 3.5 TT. Now that I have the 2017 Expy, I see how wrong I was. Truly a better engine for all purpose driving.

I started using 87 octane and switched to 91 after a few tanks. There is a difference that only the individual can judge.

Simply put, do an experiment. Try it. If you don't notice a difference in performance, go back to the 87.

Fortunately, the cost difference between 87 and 91 here in NE Nevada is only about a dime, so not a big financial hit for me.

 

[LokiWolf]

You are absolutely correct however a lot of people haul daily with 250's with gas jobs and everyone seems to think it can compete against the 6.2 motor which I disagree with in that kind of application. That is my point that if it could beat out the 6.2 long term it would be available as an option, it is however not. I guess this whole mini rant is that I think even though the ecoboost is a good engine another option would be nice as most others are offering a few configurations to the consumer.

Not sure why the 6.2 came into the mix...NOT EVEN THE SAME Ballpark. The direct competitor for the 3.5 is the 5.0. The 6.2 is a BEAST, no question, but its MPG is terrible, just ask a Raptor Owner. The 3.5TT is sized well for the 150. Want the equivalent to compete with the 6.2 look at the 6.7, yes it is a diesel, but that is it's Turbo Charged Equivalent. You might see the High Output 3.5 in the Super's in the future but I doubt it. Ford probably doesn't want to muddy the waters, and add a 3rd choice.

Again, YES the 3.5 MPG goes down to a V8's MPG when towing, but it tows better! It has more peak torque, and more in general through the Powerband than the 5.0. Again, I have said it SO many times. Same MPG, more Power seems to be the 3.5's advantage.

 

[drewactual]

the entire concept behind boost outside of performance circles is "on demand" or "when you need it".

if a 5.0 engine had 100% VE, it's displacing that 5.0L every full cycle of the engine. it's not a partial pump. it achieves it's power through adding RPM's and air, and catalyst (fuel) accordingly. it has a fraction of the moving parts compared to a boosted engine, and especially lacking the high RPM's of a turbo, where balance has to be perfect and seals and bearing always replenishing their lubricity. so... yeah. boosted application have points of failure n/a's don't have.

however.... a 2.5L engine, if it also enjoyed 100% VE, and equipped with boost capable of one atmosphere (14.7#'s at sea level) and reaching that boost is now pumping the same VE as the 5.0 mentioned above... precisely the same... and using the same volume of catalyst (fuel) to do so.... creating the same power.... but it DOESN'T when boost isn't demanded. when boost is idle (at 0psi) it burns fuel required for a 2.5L engine, not a 5.0L engine. on demand. when needed.

I watch my boost on my 6.4PSD closely- i only run it hard enough to achieve the goal- no racing around in a 12k# pickup, though it will hit 60 in right at five seconds and a 1/4 in high 12's low 13's. off the line boost is near 25# even on low/moderate acceleration... on the highway? it holds about 8~10#'s. it's not needed.

n/a gassers built to provide towing power for a 10k load, if not geared properly, expend their available energy off the line- and the rest is wasted once inertia is established, and because it takes a fraction of power to keep something going as it does to get it there. that means you're burning excess fuel after it's rolling. boosted applications don't have this problem.

a boosted application of the same displacement and VE as a n/a application is done for performance purposes... you can fit a small block in a mustang, let's say, where a big block won't fit. boosting allows performance of the big block in a space the big block can't fit. hella more power to footprint and weight ratio...

boost is the direction of the future where internal combustion is concerned. the biggest reason all engines and vehicles aren't equipped with it is the OE investment in tools, casts, and dies- and the added expense of additional parts. that's it.

 

[LokiWolf]

Jeff lays it out with the science.

As did I 2 pages before him!...

Fortunately, the cost difference between 87 and 91 here in NE Nevada is only about a dime, so not a big financial hit for me.

Lucky!! 70 Cents here on a good day!

 

[drewactual]

Just a simple chime in here on this topic. Lots of back and forth on the virtues of the higher octane with little science behind the comments. Jeff lays it out with the science. I bought my 2012 F-150 with the 5.0L thinking it will be a better performing engine than the optional 3.5 TT. Now that I have the 2017 Expy, I see how wrong I was. Truly a better engine for all purpose driving.

I started using 87 octane and switched to 91 after a few tanks. There is a difference that only the individual can judge.

Simply put, do an experiment. Try it. If you don't notice a difference in performance, go back to the 87.

Fortunately, the cost difference between 87 and 91 here in NE Nevada is only about a dime, so not a big financial hit for me.

if you're rolling around with a low compression engine, the fuel you're running's rating isn't going to impact you much. on an engine with moderate to high compression, running a low rand count fuel is a good way to destroy the engine via catastrophic pre-detonation.

(edited to add: low compression engines such as those designed for boost or those built for long life... boosted are low because the forced air induction dramatically impacts the dynamic compression, making their cylinder pressure increase- making less margin for error... and why higher rated octane is safer in them)

it's all 'bout the stored energy of the air+fuel being utilized to it's best advantage.

igniting the air:fuel earlier (degrees prior to tdc) allows the combustion to happen uniformly when the wad is packed at TDC and in the combustion chamber- if it ignites (explodes) prior to that the piston is forced down by the explosion/burn while the crank is still pushing it upward. bad things happen. a catastrophic predet can blow out a piston face, snap a connecting rod, blow a head gasket, shatter rings, and a bad enough one can do it all at once.

lower compression means more space in the cylinder/combustion chamber to absorb the power of a predetonation... but it also means the power generated by the burn is absorbed too- which means less power available in the power stroke. high compression means more power available in the power stroke, but also hella less margin for error. the rand count of fuel which combines to give it a octane rating is simply fuel that is more stable- more predictable when it ignites... less likely to ignite under compression alone... easier controlled. less pre-detonation. engine sensors can advance spark advance to more profitable range. more power available because and only because the pcm/ecu senses it can safely advance the timing.

i notice a lot more increase in power with recreational fuel (zero ethanol) of the same rating than i do ethanol laden fuel of the same rand count. cooler. cleaner. evidenced by monitoring lamda from o2's and watching STFT and LTFT crossing zero constantly. and THAT is what it boils down to... if you can 'cross zero' constantly on 87octane, there is nothing going to help you with 93octane... if 93 octane allows you to cross zero, and 87 doesn't, well... run 93.

 

[JExpedition07]

lol sorry for bringing in the 6.2 but I did because GM offers their 6.2 in the SUV segment and the 6.2 in the truck community is widely considered the successor to the 3V 5.4 Triton which were found in these trucks. Good discussion though as I agree there is a lot of future in the turbo engines.

 

[LokiWolf]

lol sorry for bringing in the 6.2 but I did because GM offers their 6.2 in the SUV segment and the 6.2 in the truck community is widely considered the successor to the 3V 5.4 Triton which were found in these trucks. Good discussion though as I agree there is a lot of future in the turbo engines.

The only GM SUV you can get the 6.2 in is the GMC Yukon Denali(Both Regular and XL), even the Chevy Suburban has the 5.3. I drove them all when I was looking at the Expy for the wife.

The 5.3 is a DOG in comparison to the Eco, and a Suburban with the same options as my Expy was several K more expensive. The Denali was REALLY expensive, but nice.

 

[07xln]

Recommended or required, what's the difference? Having to use premium, in a SUV is unacceptable and a waste. Ford is trying to appeal, to soccer moms, who want gas mileage, with the 3.5l. If I worried about gas mileage, I would not drive a Expedition. I do not know why, they can't give people a V8 option. I bet it would outsell the 3.5lt

rec·om·mend
ˌrekəˈmend/
verb
past tense: recommended; past participle: recommended

1. 1.
   put forward (someone or something) with approval as being suitable for a particular purpose or role.

re·quired
rəˈkwī(ə)rd/
adjective
adjective: required

1. officially compulsory, or otherwise considered essential; indispensable

I see quite a big difference

The Ecoboost in the F150 outsells the 5.0. Not sure why you think that would be different in an SUV

Video of 6.2 vs ecoboost in 150s, sorry to get off topic but it is a relevant issue about options, I think it's fair to ask for a V8.

What is this video supposed to prove? The V8 gets the jump and the Eco stays right with it the entire time. A drag race is not the only measure of an engines performance

I have to agree with some of what rjdelp7 said. If ANY manufacturer designs a truck motor that requires premium they would be shooting themselves in the foot. Companies with fleets wouldn't buy it, and most average consumers would stay away from it also unless they had money to burn. While I like my eco I would've opted for the 5.0 if it was an option. Not because of sound or power or gas mileage. Because in the end I think it will be a less expensive motor in the long run

Its not required its recommended. And the Expedition is in no way a fleet vehicle. You probably cant name one company that owns a fleet of 15+ Expeditions

You are absolutely correct however a lot of people haul daily with 250's with gas jobs and everyone seems to think it can compete against the 6.2 motor which I disagree with in that kind of application. That is my point that if it could beat out the 6.2 long term it would be available as an option, it is however not. I guess this whole mini rant is that I think even though the ecoboost is a good engine another option would be nice as most others are offering a few configurations to the consumer.

True but the configurations you mentioned are only offered in luxury SUV's with a high percentage of owners who have no intentions of using them to tow. People don't by Escalades or Denalis with the intent to tow 9klbs around regularly, they just don't. I had an 09 Escalade and towed a 6X12 enclosed trailer with two race bikes in it regularly for two years and it was a dog. Where talking about maybe 4Klbs. My Eco tows my 8800lb toy hauler better than my escalade ever did on its best day with half the weight.
Nobody is saying a V8 option would be bad. There simply isn't one and it's not needed. The Eco makes good power in the 15-17 and even better power for 2018. The 6.2 in the GMs are old and tired and the Eco beats em plain and simple.

 

[The dude]

0

 

[The dude]

Its not required its recommended. And the Expedition is in no way a fleet vehicle. You probably cant name one company that owns a fleet of 15+ Expeditions

That is true its not a fleet vehicle but it does have the same 3.5 twin as the pre 2017 f150