Altitude.
But for who? There's 3 cars left in America that use a carburetor. Don't the computers adjust for the proper air/fuel mixture?
The sale of 85 octane fuel was originally allowed in high-elevation regions—where the barometric pressure is lower—because it was cheaper and because most carbureted engines tolerated it fairly well.
jews
Of course you are. Did it hurt much after the operation?
Oh dayum
It's fine, we go on play dates.
Shit burns different up above 4000 feet. I've had issues with chainsaws and lawn mowers needing major choke adjustment from where it was at lower elevations. I haven't noticed any difference in my car using 85, but have been told if I go back towards sea level I will notice a knock develop
Complete BS (RE: knock if you change elevation)
I was born and raised in Wyoming, folks are still in Montana while I'm suck with my wifes lunatic family along a coast. Twice a year I drive back and forth, and have done so since 1999. For the decade before that I was single and traveled the country in a carbbed 1986 Jeep that was bought new in Wyoming (and lived on a steady diet of 85 for over 100k miles). No knock developed on the jeep, and have no issues with my current vehicles (modern EFI or the '66 Bug that we tow occasionally). Even monitoring my engine run conditions (Torque Pro app and OBDII) shows no real deviation in operating conditions between near sea level and upwards of 8000' in elevation while running the cheapest gas I can find (well, not e85).
The issue you've found with your small engines is true for big vehicles too, there's less oxygen density in the atmosphere and you have to change the carb jetting/settings to compensate and get back to a stoichiometric (efficient) setting. Track down any old VW guy who's traveled to elevation and ask if they rejet at elevation (or carry spare carb jets). Closed loop EFI (the norm today) handles this without issue... Open loop could deal with some elevation change but generally had different "maps" for elevation ranges.
As for the original question, I only have my personal understanding of it as explained by an oil engineer I know at one time and no hard facts, but RON+MON is derived by running fuel through a CFR engine (calibrated test engine designed with this specific task in mind). Take the same fuel and test it at 0/sea level and 5250 (1 mile) above sea level and your output number is different. The fuel is the same, test equipment is the same, operator is the same... the only change is the air density. Nothing "different" about the fuel other than where it's tested.
As for those who've read their owners manuals about using a minimum 87, most either have small print right next to that stating "or equivalent" or have a separate section for operating at elevation where it covers the alternatives.
lol then add 10% ethanol to that, gas is even more expensive
Dude I just paid $7.18 for a fucking 18 eggs. And they're pretending it's caused by bird flu?
Octane levels have to do with compression ratio of the engine. Higher compression ratios need higher octane rating. What the fuck does a carb have to do with it?
So you're brand new Jeep Renegade put 85 octane in it what will happen? How come there's not 85 octane back east?
Nothing would happen to a Jeep Renegade. You could put 83-95 octane fuel into it without issue. Compression levels are low enough. Let’s say you buy a Porsche, and you put 85 Octane in. The fuel would start combusting “detonating” before the spark plugs fire. The car would sense this via knock sensor and start to retard the timing. Thus giving you less available power.
Sort of an interesting extreme example of higher octane was would war two. Engine made later in the war required 147 octane in order to run correctly.
Interesting. So would this eventually foul out the spark plugs and or cause a lot of dirt/grim in the fuel system?
Because of the jews, niggers, trannies, and faggots.
Rod knock is why.
But how come I can't use it in my van, it tells me I'm only allowed 87.
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