What octane gas at high altitude?

What octane gas is everyone using at altitude? Here in CO basic gas is 85 and wondering if anyone else is using that at higher altitudes without any problems?

 

I've driven several different vehicles up and down I70 west of Denver, no problems other than lower power output on naturally aspirated machines, turbos and chargers are essential (to me) above about 6K altitude.

 

thanks for the reply! So sounds like I shouldn’t have any problems with the tundra using 85 octane.

 

Yup that’s what the manual says but there’s also a reason why 85 is “regular” gas at high altitude versus 87 at sea level.

 

I always thought to use higher octane while towing because there is more stress on the motor. Just like climbing in elevation…there is more stress on the engine. I would use the highest octane possible with a turbo’d engine. Please let me know if I am wrong.

 

What model year Tundra are you driving?

If it is a 2022 model it will have turbochargers on it. The turbochargers don’t care what altitude you are at, if there is enough air available to produce positive intake manifold pressure once the turbine side (hot side) of that turbo spins fast enough then your altitude is meaningless. The turbochargers effectively compensate for or eliminate altitude as a limit on power output.

Your naturally aspirated engines running at 3,000ft above sea level or higher will be OK on 85 Octane assuming they’re designed to run on 87 Octane at sea level. They’re not sucking in air at 14.7lbs/sq-in like they would be at sea level; at 3,000ft atmospheric air pressure is nominally 13.2lbs/sq-in, and it continues to drop the higher you go. For example TFL Truck starts their Ike Gaunlet testing high enough air pressure is just above 10PSI and ends just below 10PSI.

A turbocharger capable of positive manifold pressure will not be safe using a lower grade of fuel. The engine will be using air at a higher pressure than sea level all the time under boost regardless of altitudes an internal combustion engine is capable of running at. Most modern turbocharged engines can make more boost than they are tuned to use and bleed off the excess capacity via the wastegate to prevent over boost. As the altitude get higher and the ambient air pressure reduces the wastegate has more than enough range to compensate by not bleeding off as much pressure. So the system still makes full boost most of the time. If the turbo engine is tuned to make 15lbs/sq-in of boost at sea level, it’s going to very likely make it at 10,000ft too by spinning a bit faster and not opening the wastegate as much or at all. So if the truck calls for 87 Octane feed it 87 Octane at a minimum.

 

I would never use it in a modern turbo vehicle. Here is a video explaining some of the science why not to: https://youtu.be/kJyd6C99_3g

 

This^^^^ My Frontier calls for 87 too. Buy top tier 87 fuel. FYI...Sam's Club doesn't sell 87 here in Colorado. I never buy fuel there.......

 

Yeah… use the minimum recommended 87 octane. Even at 5000 ft elevation, the cylinder pressures are nearly the same as at sea level due to the turbo so you’ll get knock with 85 octane.

 

Both of my non turbo 5.7 Tunnies hauled ass over LaVeta Pass, 9413 ft, loaded down with camping gear in the bed and hauling rock on my 17ft trailer. Always had to back off near the top. Never ever noticed lower output. Got scary actually at times with the power...my property is at 8300 ft. A bit north of 6K.

 

Wow I learned a lot from this thread. Great posts, great video.

 

This is an interesting comment. I’m curious, have you driven your Tundras at sea level? Or have you driven a F150 ecoboost at elevation? I think the Tundra loses a ton of power, especially above 8000 ft. I’ve never towed with the 5.7 Tundra but I towed a 10,000 lb trailer with a RAM 5.7 V8. That truck could barely hold 50 mph going up I70 east toward Denver through the Johnson tunnel. That’s like 10,000 ft I believe. The RAM hauled the trailer up I15 cajon pass no problem though, that’s much lower elevation but a similar grade. Not sure the grade at LaVeta Pass but typically mountain highways are limited to 6% max grade by design.

 

Yea it will be the 2022.

Thank you for the detailed explanation really makes a lot of sense now. Definitely will only go with 87 now.

 

Awesome video thanks for posting it!

 

Is UNL88 (once known as E-15) available in CO?

I would probably run that at high elevation.

It's perfectly fine to use in the new Tundra.

 

The lowest in altitude I ever drove my Tundra's was around here on the front range. Never towed a 10K trailer with my either Tundras and quite frankly I would never consider that. The "Eisenhower" (Johnson) tunnel is actually over 11K and yes the La Veta Pass grade is typical for mountain highways. If I was towing a 10K trailer I wouldn't recommend the Tundra. Go larger.....

 

Not much ethanol based gas here at all. Hard to find any ethanol gas other than dino with 10% ethanol added.

 

Yeah that’s right, the entry to the tunnel is actually right at 11k. Loveland Pass next to it is at 12k and you get a pretty decent view of the tunnel up there. I was just passing through… I did the same drive with an F250 Powerstroke and it felt much more stable with the RAM. Same trailer, same weight.
Anyway, I’ve never expected to hear any NA engine feels powerful at elevation. Even the GM 6.2 V8 feels like a dog above 8000 ft.

 

I'm running Premium right now.

Anybody else run Premium?

91 I think

I have the 5.7

 

I’m running 91 in my ‘22. I live in Salt Lake City so not Denver high but still 4300ft+

 

Is the TT supposed to take only 91? or is 87 acceptable as well?


I live at 400
Willamette Valley OR

I am getting slightly better mileage with 91 in this 5.7, or my engine is breaking in
Not sure yet

 

They can run 87 no problem but should benefit from 91+ from both a performance and MPG standpoint. The MPG's may not change much, but it will be there.

 

Thanks.
The 5.7 as well as the 2022 V-6TT?

Just now realized I am in the Gen 3.0 thread, just did a search for octane and ended up here

 

I wish costco sold 87 here in colorado

 

Correct, turbos benefit from higher octane fuels and dyno with more horsepower, your engine will get worse mileage on low octane fuel, it will cause much knock, retard the timing and possibly run hotter.

Look at the Bronco turbo engine ratings, Ford is now listing two different sets for the different fuel qualities.

 

Ford has different tunes for different octane. I don't think Toyota does. While higher octane may prevent the knock sensor from pulling power, it's unlikely that it makes any real world difference in power or mpg. Anecdotes for days but without different fuel maps, the benefit just isn't there

 

Its hard to say Ford has different tunes because usually the engines are not the same between platforms. The 2.3 in the ranger is no the same as the 2.3 in the Mustang which is not the same as the 2.3 in the Focus RS. So yes their tuning is going to be different.

Ford doesnt necessarily have different tunes though when the engines are the same. They just have different power ratings for different octanes. An Ecoboost PCM will not only pull timing, but also reduce air load(boost) based on the calculated octane rating of the fuel. So its a double whammy in a sense. You lose timing and boost at the same time. The 2011-2014 3.5 Ecoboost was less aggressive about this, but the 2017+ trucks are pretty aggressive and can add a significant amount of power by running 93 octane vs 87. A 2017+ on 87 octane might make 320 whp, but they can make 355-360 on 93.

Unless Toyota simply caps the air load at whatever it should be to run 87 octane, then it could potentially pick up a good amount of power on 93.