Ford Mustang EcoBoost Loses Big Power on 87 Octane

What "performance" machine do you drive? Or have owned?

Increased octane does not add power. It only prevents detonation. If your car is built for 87 octane, your performance increase moving to high octane is minimal to none. But, super/turbocharged engines and engines with high compression and/or advanced timing need higher octane to prevent predetonation. Using lower octane causes the computer to make changes like retarding the engine timing and loss of boost and a significant power loss is observed. In other words, if your car is designed for 87 octane, anything higher is a waste of money. If it's designed for high octane, anything less shouldn't ever be considered.

You mention you are 110% against running premium for several reasons, but other than cost you fail to list any. Its not that manufacturers cannot make cars that will run on 87 octane, its that it cannot make 310 HP 4-cylinder engines that will do it. I suggest doing some research on why vehicles require higher octane. And no, its not because uncle Bill puts premium in his Yaris and gets an extra 25 hp. It doesn't work that way. By the way, who is really buying a 4 cylinder mustang anyway? Pulling up beside a GT in a 4-cyl. is like walking up next to a horse at a urinal. Just save up and buy the real car, otherwise get a focus/fiesta that are meant for 4 cylinders.

You kinda have to understand how higher octane gas works to get this but the octane rating has nothing to do with the "power" of the gasoline but rather it's ignition point and burn time. Premium gas does not contain more chemical potential energy than regular gas at all. 93 octane gas actually burns slower and is harder to ignite than 87 octane, hence it's less volatile. Here's a simple explanation of why some cars need premium. You want your engine to ignite the fuel in each cylinder at precisely the right time in the engine cycle otherwise things can go boom and get expensive quick. Cars with a higher compression ratio or forced induction (like this turbocharged mustang) tend to generate higher pressure in their cylinders which makes them more predisposed to premature detonation which could lead to catastrophic engine failure. Modern engine management computers will remedy this by spraying more fuel into the cylinder as this drops the air fuel ratio and lessens the chance of predetonation. For max power your car needs an optimal ratio of air and fuel mixed in the cylinder but like I said the engine management computers in these cars are trying to prevent the thing from blowing up harder than they are trying to make max power. Higher octane gas being less volatile allows the engine to run with a more optimized air fuel ratio and thereby make more power (assuming the ecm is calibrated for premium). In other words, this engine is intended to run premium therefore it can safely make more power on premium. Fill it up with regular and the ecm de-tunes the engine for safety purposes.

If you don’t understand simply engine engineering you shouldn’t make stupid statements. Your Hyundai really isn’t a fancy vehicle anyway. It’s basically turboyd to give that pos enough power to keep up with its own shadow. So to keep from getting run over spend the few extra pennies at the gas pump or purchase a desent car in the first place. I also doubt that the actual figures were close regardless of fuel used. That’s assuming it was tuned correctly for premium fuel. Also not using a Top Tier premium fuel will create many negative problems down the road for any turbo engine.

If it were 20 cents it would be a no brainer. Around here it’s 80 cents. That’s significant if you don’t hot rod it and just use it for transportation.

Then stop living in DC. That's your problem. If you don't live in expensive places then you don't have to put up with $.60 cents per difference prices in octanes. Nobody held a gun forcing you to live in DC. You chose that on your own free will. That's your own fault. Move to a cheaper state.