85/87/89/92 available here in northern Nevada.
Only a few pennies (2-3) difference between 85 & 87.
Only a few pennies (2-3) difference between 85 & 87.
85 octane... Wth?
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Originally Posted By: Rand
Originally Posted By: AirgunSavant
The guys at Exmark wanted me to run nothing lower than 89 because they want you to get more
additives in the fuel. I use 87 and just use an ethanol treatment which they suggested at each use as well.
That was the choice 89+ or 87 with Star Tron- their suggestions
Originally Posted By: WylieCoyote
I see lawn crews pumping from the 85 pump all the time. A lawn mower is the only thing I'd use 85 in.
Makes no sense.. generally speaking 89 has no more "additives" than 87.
Not always true... A lot of stations have top tier as their minimum standard then like 2 or 4x the detergents in their premium
Originally Posted By: AirgunSavant
The guys at Exmark wanted me to run nothing lower than 89 because they want you to get more
additives in the fuel. I use 87 and just use an ethanol treatment which they suggested at each use as well.
That was the choice 89+ or 87 with Star Tron- their suggestions
Originally Posted By: WylieCoyote
I see lawn crews pumping from the 85 pump all the time. A lawn mower is the only thing I'd use 85 in.
Makes no sense.. generally speaking 89 has no more "additives" than 87.
Not always true... A lot of stations have top tier as their minimum standard then like 2 or 4x the detergents in their premium
Drove all over the west in a rental car, pumped 85 in it the whole time. Noticed nothing.
I would put higher octane fuel in a supercharged or high compression engine. Most run of the mill econoboxes shouldn't mind.
I would put higher octane fuel in a supercharged or high compression engine. Most run of the mill econoboxes shouldn't mind.
Originally Posted By: JustinH
Drove all over the west in a rental car, pumped 85 in it the whole time. Noticed nothing.
I would put higher octane fuel in a supercharged or high compression engine. Most run of the mill econoboxes shouldn't mind.
More and more of those "run of the mill econoboxes" are turbocharged nowadays. I'd run the recommended 87+ octane in them. Quite a few owners won't, and somebody's going to explosively vent a block.
Drove all over the west in a rental car, pumped 85 in it the whole time. Noticed nothing.
I would put higher octane fuel in a supercharged or high compression engine. Most run of the mill econoboxes shouldn't mind.
More and more of those "run of the mill econoboxes" are turbocharged nowadays. I'd run the recommended 87+ octane in them. Quite a few owners won't, and somebody's going to explosively vent a block.
Originally Posted By: A_Harman
Originally Posted By: MNgopher
Normal stuff in high altitude areas and generally works fine where 87 octane is used and you will remain at higher altitude. Won't use in a turbo vehicle, but in NA its fine.
Agreed. Modern turbocharged engines are controlled to achieve a certain manifold absolute pressure before opening the wastegate(s). So if it is running at altitude, the turbo will spin faster to make higher boost pressure, and the engine will make the same power as it does at sea level. Not a good time to put lower octane fuel in.
How many turbocharged engines made in the last 20 years DON'T have knock sensors?
Originally Posted By: MNgopher
Normal stuff in high altitude areas and generally works fine where 87 octane is used and you will remain at higher altitude. Won't use in a turbo vehicle, but in NA its fine.
Agreed. Modern turbocharged engines are controlled to achieve a certain manifold absolute pressure before opening the wastegate(s). So if it is running at altitude, the turbo will spin faster to make higher boost pressure, and the engine will make the same power as it does at sea level. Not a good time to put lower octane fuel in.
How many turbocharged engines made in the last 20 years DON'T have knock sensors?
JHZR2
Staff member
High altitude operations allow for lower octane. No issues...
Originally Posted By: Jarlaxle
Originally Posted By: A_Harman
Originally Posted By: MNgopher
Normal stuff in high altitude areas and generally works fine where 87 octane is used and you will remain at higher altitude. Won't use in a turbo vehicle, but in NA its fine.
Agreed. Modern turbocharged engines are controlled to achieve a certain manifold absolute pressure before opening the wastegate(s). So if it is running at altitude, the turbo will spin faster to make higher boost pressure, and the engine will make the same power as it does at sea level. Not a good time to put lower octane fuel in.
How many turbocharged engines made in the last 20 years DON'T have knock sensors?
None. But then it will retard spark, and the engine will lose performance.
Long term running with retarded spark may cause excess exhaust valve seat recession.
Originally Posted By: A_Harman
Originally Posted By: MNgopher
Normal stuff in high altitude areas and generally works fine where 87 octane is used and you will remain at higher altitude. Won't use in a turbo vehicle, but in NA its fine.
Agreed. Modern turbocharged engines are controlled to achieve a certain manifold absolute pressure before opening the wastegate(s). So if it is running at altitude, the turbo will spin faster to make higher boost pressure, and the engine will make the same power as it does at sea level. Not a good time to put lower octane fuel in.
How many turbocharged engines made in the last 20 years DON'T have knock sensors?
None. But then it will retard spark, and the engine will lose performance.
Long term running with retarded spark may cause excess exhaust valve seat recession.
It's strange but this doesn't happen in Europe AFAIK, i've been to the Alps and Pyrenees in my car and never saw anything lower than 95 RON, that is the lowest octane you will find across most of Northern, Central and Southern Europe and the UK and Ireland highest about 100 RON which would be Shell V-Power
Originally Posted By: horse123
Saw this all over in Idaho and Utah. You won't open a manual for a car made in the last 15 years that says anything below 87 is OK. So what's the deal? Is it just a cash grab so they can list their 85 the same as everyone else's 87 then charge you more for their 87?
Staying in town...use it. Driving through town and dropping elevation ask for mid or premium for higher octane. That's my motto. However, I doubt if running a little 85 for a few miles of low elevation would do anything bad. Computers adjust.
Saw this all over in Idaho and Utah. You won't open a manual for a car made in the last 15 years that says anything below 87 is OK. So what's the deal? Is it just a cash grab so they can list their 85 the same as everyone else's 87 then charge you more for their 87?
Staying in town...use it. Driving through town and dropping elevation ask for mid or premium for higher octane. That's my motto. However, I doubt if running a little 85 for a few miles of low elevation would do anything bad. Computers adjust.
Modern engine management can compensate for the thinner air, so newer cars need to use at least 87 regardless of altitude. The MAF will automatically adjust.
Originally Posted By: FordCapriDriver
It's strange but this doesn't happen in Europe AFAIK, i've been to the Alps and Pyrenees in my car and never saw anything lower than 95 RON, that is the lowest octane you will find across most of Northern, Central and Southern Europe and the UK and Ireland highest about 100 RON which would be Shell V-Power
95 RON = 91 US octane (before the trolls say "but their octane numbers are different in Europe!")
I think Russia is the only European country that even sells 91 RON (87 US)
Originally Posted By: FordCapriDriver
It's strange but this doesn't happen in Europe AFAIK, i've been to the Alps and Pyrenees in my car and never saw anything lower than 95 RON, that is the lowest octane you will find across most of Northern, Central and Southern Europe and the UK and Ireland highest about 100 RON which would be Shell V-Power
95 RON = 91 US octane (before the trolls say "but their octane numbers are different in Europe!")
I think Russia is the only European country that even sells 91 RON (87 US)
Modern engine management cannot change air density so the maximum cylinder pressure with a naturally aspirated car will be lower at high altitude. Lower pressure and less heat reduce octane requirements. That the engine management compensates for the lower mass of air doesn't change the physics. All it does is keep the mixture correct.
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