7.3 Gas, Octane & Elevation

[stevenc]

Until recently, had never seen 85 as I'm from New England.   I now reside mostly around 7000' & my only feedback is that the current turbo F150 has been happier w/88 which to me makes sense.

 

Where are you? What are you running?  Thoughts?   Cue the ?

[rick johnson nm]

My 6.2l manual says never use anything less that 87 octane. Quote:

 

Some fuel stations, particularly those in high altitude areas, offer fuels posted as regular unleaded gasoline with an octane rating below 87. The use of these fuels could result in engine damage that will not be covered by the vehicle warranty.

[NH_Bulldog]

I am in New England.  I run 87 in my 7.3L for average driving and get between 15-16 mpg in mixed use but bump up to 93 for towing just like I did with my F150 3.5L Ecoboost.  The manual says 87 is good, but for best results they suggest that you use at least 91.  We have not towed yet (first trip is scheduled for next week).  I might try a tank of 91 and see how it does.  

The only real issue I see is that every station I have been to lately stops the pump at $75 which could be as little as half a tank of gas.

[IUEC135ELEVATOR]

7.3....I am at 850 ft when at the house....been towing 8500lbs @ sea level and this week been in Gatlinburg tn mountains from 1200‐1500 towing...non towing just driving around from 1200 to 6000.

 

I always run 87..

 

to be honest I can't see any or tell any differences between the elevations when it comes to power or mileage.

 

I am sure there is some but can't tell by seat of the pants or debit card.

[road turtle]

In my F150 towing a smaller travel trailer (23ft), premium non ethanol gas was amazing.  I didn't check fuel economy, but it definitely improved engine performance.

[stevenc]

My original post now seems a bit vague.   I find it interesting that 85 octane is still so prevalent here in the west at elevation.   I understand how it originated & there are arguments in both directions on whether it is "ok" to use.   There are soooo many people filling up daily with 85 in modern vehicles that clearly have a minimum rating of 87.    

 

I recently turned my brother in law onto this in regards to his 2018 150 eco boost.   My suggestion to him was to run 88 at a minimum (87 is not available here) & when towing the RV bump up a notch.   He was surprised at the results. 

Edited April 25, 2022 by stevenc

[MackFord]

I agree, I wouldn't fill with anything less than 87

[UT_Grandpa]

Octane requirements are lower at elevation.  Where I live it is about 4500' MSL and 85 octane is "Regular" with 88-91 octane "Premium".  Octane helps reduce "pinging" of the engine sometimes referred to as knock.  There are knock sensors on all engines made in the past 25 years or so that will retard the timing if knock occurs so as to protect the engine.  If you drive 300 miles south of where I live at an elevation of under 1000' MSL the regular gas has an octane of 87-88 and premium of 91.  The lower elevation (more dense air into the engine) needs a higher octane.

 

Turbocharged engines are a totally different story.  The turbo increases the air charge into the cylinders (more dense) regardless of elevation and really runs better with a higher octane gas.  We have a 2018 Honda CRV with the 1.4L Turbo engine and it does run better on "premium" and delivers about 10% better mileage using the higher octane fuel.  The fuel costs more but it gives a marginal lowering in fuel costs.  The Honda dealer said the lower octane fuel is Ok to run without any damage.  So when the weather gets hotter or we are going on long trips we fuel with premium fuel.  That's what we do and it works for us.

Edited May 1, 2022 by UT_Grandpa
spelling fix

[Black Label]

23 minutes ago, UT_Grandpa said:

Octane requirements are lower at elevation.  Where I live it is about 4500' MSL and 85 octane is "Regular" with 88-91 octane "Premium".  Octane helps reduce "pinging" of the engine sometimes referred to as knock.  There are knock sensors on all engines made in the past 25 years or so that will retard the timing if knock occurs so as to protect the engine.  If you drive 300 miles south of where I live at an elevation of under 1000' MSL the regular gas has an octane of 87-88 and premium of 91.  The lower elevation (more dense air into the engine) needs a higher octane.

 

Turbocharged engines are a totally different story.  The turbo increase the air charge into the cylinders (more dense) regardless of elevation and really runs better with a higher octane gas.  We have a 2018 Honda CRV with the 1.4L Turbo engine and it does run better on "premium" and delivers about 10% better mileage using the higher octane fuel.  The fuel costs more but it gives a marginal lowering in fuel costs.  The Honda dealer said the lower octane fuel is Ok to run without any damage.  So when the weather gets hotter or we are going on long trips we fuel with premium fuel.  That's what we do and it works for us.

Are you a pilot like me? Most people don't use MSL when referring to altitudes. 

Edited April 26, 2022 by Black Label

[IUEC135ELEVATOR]

2 hours ago, Black Label said:

Are you a pilot like me? Most people don't use MSL when referring to altitudes. 

 I believe he is a really old urinary technician....

 

 Going off the screen name?

[UT_Grandpa]

On 4/26/2022 at 6:09 AM, Black Label said:

Are you a pilot like me? Most people don't use MSL when referring to altitudes. 

I am a pilot.  I do not have a current medical but did fly with my friend to Oshkosh this past summer and got a bunch of hours on the way there and back.  He has a 1964 C-182.  Nice plane.