Where I'm at (Delaware) you can get 94 at some of the Sunoco pumps, and 100 around the Dover track (and yes, aviation fuel (c16?) if you know where to find it). For one, its not good for the catalytic converter. When untuned for, high octane fuel will eat up the materials and eventually lead to blockages because it will basically disintegrate into fine dust. Its not going to make a power difference in a car thats electronically adjusting timing, which is why you can get away with 87 sometimes and if you're not beating on it. I'd never run below 91 in a turbo car. Ford using regular fuel is a hack because they know their customers are going to be cheap and ignore any advice to run premium in a pickup truck. I'm sure it runs pig rich. Some of that Wawa gas here is low quality. Forget the HP differences because the economy and longevity will make up for the difference. I'm sure its using some kind of wide band detection system to adjust for mistakes. You have to consider that they tune and design a fuel system with a certain level of error and to prevent it from being "region" specific as gas is differently formulated by elevation and supply geography. IIRC, you might only see 85 in high elevations, but since there is less O2 density in the air, you dont need the anti-knock additives to prevent detonation. FWIW, turbos do very well with mitigating power loss since they build air density.
Lower RON/octane fuel burns hotter (and unburnt fuel has a cooling effect to a point) because you're reducing octane so you can increase potential for knock and heat related wear by trying to save money. I also think GDI motors allow them to handle lower octane gas better to a point. This is also related to why a tune to lean out the cylinders on premium gas can yield a bit more power and economy as you also increase boost and optimize fuel ratio - especially if the ECU can handle the range and you're sticking to known good fuel and buying that fuel from one specific geographic location. If say, you had a protuned car in California, you might want to retune that car for safety in Maryland or it might run like crap.
Does anyone know what the cylinder compression (not the ratio) is out of curiosity?
I wonder if Hyundai will come out with factory approved tunes since they're being restrictive about the ECU changes, but their warranty is a big selling point. I would say that reilable 300whp is not out of question for this motor although being FWD and other parts might make that just a numbers game.
