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100 octane,
93 with Ethanol,
91 no Ethanol (Marine Gas)....
Dumb question I know
I’m running E85 in my boosted LS3 vehicle. It runs cooler and they can advance timing for added power. It does have a downside, it can clog up some fuel injectors so running a tank of non ethanol or fuel cleaner a few times a year is a must. You also don’t want to leave it in a tank because it collects moisture. If your car is tuned for it, run it. Otherwise, I’d stick with 93 and a bottle of injector cleaner once or twice a year. The higher end fuels have cleaners in them but doesn’t hurt.
I've heard some weird stuff about 100 octane burning too slow. To be honest I'm not well enough versed to explain or even fully recall what I read, but it was being talked about by track junkies and they recommended against it. Something about leaving orange deposits on the spark plug too...?? If someone knows what the story is with 100 octane let me know.
Theoretically, E85 can produce more power, IF your tune is set up for the fuel (mileage will suck). It's not good for the fuel system long term. Every day, I think 93 E10 is about the best you're going to find, but E93 without would be a better option (my local Shell used to be non ethanol, sadly no more). Ethanol is a political scam and serves no useful purpose; it reduces mileage, it's more expensive, it's bad for fuel systems (particularly for small engines like your lawn mower, leaf blower, emergency generator, etc), and it does nothing for the environment.
A stock 992 should be running a minimum octane of 91, with 93 being preferred if your state carries that fuel. 10% ethanol should be used as well. Avoid Costco/Sams/7-eleven type places as they carry blended and poorer fuel qualities. Best to stock with name brands such as Mobil/Exxon/Shell/VP.
Avoid 0% ethanol gases.
Running 100 octane or even higher octane gases (such as Sunoco104, MS109, etc.) are more volatile and do "burn slower" however the purpose of the higher octane is its higher resistance to pre-ignition detonation. This means that the car is less susceptible to knocking and can running higher ignition timing, therefore making more power.
100 octane gas will not leave orange or white deposits unless you are running a gas with a ton of additives. You will usually see white or orange colored exhaust tips from guys putting in "octane boosters" of some kind in their regular or race gas. In our experience, these don't work very well and can cause issues with your oxygen sensors prematurely.
One note of correction, whereas Sam's Club, Kwik Shop and some others use cheaper fuel sources , Costco and QT ( Quiktrip ) use Top Tier Fuels with the proper detergents. A good place to check is at toptiergas.com and you may find some surprises since there are a few top name brands that are not listed -- BP is a prime example. Part of the reason I go to Costco to fill up as they are always the same price as Sam's but they have the Top Tier fuel that Manufacturers recommend for their vehicles. I check the list every once in an awhile as there was a period where some top brands stopped adding the detergents to their formula. Interesting, because at present VP is another fuel not listed , like BP, and I do believe that is a surprise to most of us.
The fuel from Costco is terrible for performance cars if you are trying to make power. It's very apparent looking at datalogs from cars filled with Costco 93 or 91 that there is significantly more knock occurring than say gas from a station like Exxon or Shell.
Don't get me wrong, I love going to Costco, and I fill my daily driver with their gas and it does save me money. But if I'm going for power I would absolutely not get gas from there.
...10% ethanol should be used as well.... Avoid 0% ethanol gases....
Intrigued by this. Locally I have access to 91 non-ethanol and 93 10% ethanol and have always wondered which is preferred and why. Charles, can you shed some light on this?
Here in UK BP started selling 102 octane petrol a few years ago. It costs a fortune. What they didn’t advertise (initially) was that it’s utterly pointless unless your motor is specifically tuned for it. 98/99 octane (93 US?) is as much as the standard ECU can optimise. As for detergents in the gas, they’re designed to KEEP the fuel system clean, not clean out crap. You’ll need a dedicated bottle of jollop for that
>> Locally I have access to 91 non-ethanol and 93 10% ethanol
Ethanol, while less power-dense compared to gasoline, has greater knock resistance which is important for high boost applications like ours. That's why you see ppl running E30 and E50 blends in some tuned setups if you don't want to go through the trouble of a meth installation.
On a prior car (BMW E92 N55 with full bolt-on, big turbo and a tune), E30 was good for an extra 40 hp, which is about 10% more HP then I could make on regular E10 93, not shabby.
07-16-2023, 10:42 PM
Best gasoline for a 992 GTS ?
