>does putting the correct fuel that the engine is designed to run on accomplish anything?
Yes, obviously.

>>28867026
It probably wouldn't hurt anything to use 87, my sisters yaris has a 10.5x compression ratio compared to the 10x compression ratio of a 1999 i30 and it doesn't have problems.

my equinox recommends premium (93 where I live, idk where you gotta go for 91) but premium is expensive so I've been giving it 89 and it seems to be okay with it

>>28867026
If your car is tuned for higher octane it can cause pinging under load but the ecu usually cripples the engine enough that it rarely happens.

>>28867062
Kek a 3 Liter 190HP maxima engine from 1999 is such a lazy bitch, it doesn't even deserve 91 octane at 63HP a liter, my Honda makes 66HP/L and it's running 87, I could understand if this were like a high compression thing that made a bunch of horsepower for the size and revved to the moon, but it's a piece of fucking shit Maxima engine from eons ago.

>>28867071
>I could understand if this were like a high compression thing that made a bunch of horsepower for the size and revved to the moon
They use high compression as a workaround for being small and shit, not to have high performance.

>>28867078
Weird how pigfat engines with high compression ratios are touted as performance-oriented.

>>28867062
This also results in lower fuel economy canceling out any savings per gallon.

>>28867026
Your owners manual sez:
"Use unleaded premium gasoline with an octane rating of at least 91 AKI (Anti-Knock Index) number. If unleaded premium is not available, unleaded regular with an octane rating of at least 87 AKI can be used. However, for maximum performance, the use of unleaded premium gasoline is recommended."
So save the money when commuting.
Meanwhile, my KTM stalls taking off from stops if I use regular, so I'm screwed. (I get 60MPG tho)

>>28867026
you'd have less power with a lower octane

and it might knock and get messed up too

>>28867312
Yep, because the efficiency they want is how efficiently they extract money from your wallet on new cars.

cars "made for" premium fuel was always a scam to get gas companies rich. I bought a Honda sedan, normal shit and it takes "premium" fuel. Fuck off, I run just fine on 88

>>28867452
>cars "made for" premium fuel was always a scam
Always? No
There's a reason they call for it

If your car "requires" 91/93 then get it.
If your car "recommends" 91+ then you don't have to. Running 87 in a car that is tuned specifically for 91+ can easily blow the engine.
From a brief google search it looks like the '99 I30 only requires 87 but recommends 91, but look it up yourself to be sure.

i put 98 in my car because i like it :)

>>28867465
>Running 87 in a car that is tuned specifically for 91+ can easily blow the engine
This isn't 1980 Grandpa.

>>28867518
Do you think that physics and chemistry have changed?
Some cars can sense it and pull or advance timing or change the tables. Some cars actually need it and will knock without it. Two different things.
High compression, very advanced ignition timing, and or high boost usually requires it, and for good reason.
STis come with 14psi from the factory, are you going to put 87oct in there and do redline pulls? Surely even you wouldn't be that stupid.

>>28867026
Generally you put in high octane if the engine has issues with knocking at lower octanes.

>>28867497
>98
That's RON, we use AKI in 'murica
98 RON is 93 AKI

>>28867527
I'll take "what is EFI for $500 alex"

Using higher octane gas will only help if you have EGR troubles.

>>28867819
>He thinks EFI means he can run 87 in an STi.
Go ahead, buddy. Octane is resistance to knock (the killer of engines), more boost, compression, or timing advance require higher octane to not knock.
What the fuck would EFI even solve in the equation? I'd love to hear it.

RTFM
if the manual say premium required, you must put premium in it if you like having an engine