91 its ok.
Wont feel any difference and either wont hurt your cars.

[shrugs] I thought our ECUs have a more aggressive map for 93 octane. Even my dad feels a difference with his Z32-TT. It just seems like there's plenty more throttle response.

I feel a difference when I got from 93 to 100 but i dont know if id know the difference from 91 - 93.. I know that if you dyno tuning you can tune about 20-30hp more with 93 on a turbo car.

eh, here in dallas, i fill up at costco and their premium is 93, so thats what i go with...definitely working out so far. dont know if i'd see a performance difference if i went to a station with 91 though...

With my previous turbo'd car, I could tell..but I was running a chipped ECU that was tuned for 93. The 91 caused it to pull timing (1 degree of timing is ~5hp).

With the Z, I had a tank of 91 once but can't say that I could tell. Maybe at the track once heat causes the knock sensors to start to come into play......I might tell the difference. But for street use on a stock tune....I would hard pressed to say I would notice a difference on a NA car.

91 and 93 will perform identically in our cars. Fill up with 100 octane and you notice a difference, but not because of the higher octane, it's because 100 octane is oxygenated.

91 octane is actually technically oxygenated as well as the 10% ethanol content allows the companies to sell it as such. there is a marginal performance difference between 91 and 93 due to the alcohol content (alcohol is a cheap easy way to boost 87 up to 91 without adding the nice petroleum distillates, and fuel additives you get with 93, while at the same time reducing specific energy output by 1-2% due to that same alcohol) 91 is the gasoline equivalent of E85 and shares it's same fault only smaller, and doesn't carry the 100+ octane rating of an alcohol base blend. The 91 octane sold in the state of California is even worse dues to it's requirement to further reduce emissions. Gasoline mixes also vary by region, and time of year as well as by brand. You may like shell in spring, B.P. in summer, Mobil in fall, because each company varies the amount of additives in they specific blend they order, and many companies actually sell the exact same gas purchased from the local oil distributor, some times you can even watch a tanker pull in to one station unload fuel, cross the street and put the same gas in the competitors tanks. This time of year i have to be careful with roadtrips to no-snow states because on the drive home if i have that fuel left in the tank there isn't enough antifreeze in it once you get back into sub 10degree weather.

Edit:Many places now also sell a 10% ethanol blend in 93 octane rating as well so that is something to look for because in many states companies are not required to actually state what is in the fuel so long is it is in quantities less than 10% and meets the advertised octane rating

You guys are *******.

Me, Im running JP-5. I definitely noticed a performance difference, on the stock tune.

Our only choices here are 87, 89, & 93 octanes. I have filled it the first 3 times with 93, but what about 89? Would you use it? :confused:

Definitely not. The car is tuned for 91 octane - any lower, and you better be pretty soft on the throttle, and never take it to "oh ****" RPM's. Otherwise, knocking is almost inevitable.

yeah 89 is a for sure no-go especially since most companies stoop to a mid tier gas that is almost always blended, for everything except premium(some stations screw that up too as i said)

Edit: oh and bobo we can get 110 oxy unleaded here

I'll stick with my JP-5. You know what JP-5 is used in, right? Its exclusive! "High" rollers, only!

yeah yeah you use your aviation grades the rest of use will stick to our 93, painthinner, and race gas

110+tolulene = 130octane of pure FTMFW

Look up JP-5 specifically :)

Well.......That's not entirely true. With today's adaptive ECU's, the knock sensor will allow the advance of timing up to the point of detonation then back off slightly for maximum power and efficiencies. Higher octane allows more timing to be advanced with a result in slightly more performance. Cooler Intake temps also allow this advance. I've posted numerous charts and graphs on this in the past so I'll spare you that. The 370 ECU has proven to be very adaptive which is one reason it responds so well to mods without re-tuning and will respond to higher octanes as well, at least up to the max adjustment range within the ECU programming. . As an example from the Audi camp, the difference between a 93 octane program and a 100 octane program on a 1.8T motor is roughly 15-20 hp. The differences between the programs are are primarily timing advances...