What do the stock ST's use? I was unsure so I filled with with mid grade 89octane.
87 octane is the minimum recommended fuel.OCTANE RECOMMENDATIONS
Regular unleaded gasoline with a
pump (R+M)/2 octane rating of 87 is
recommended. Some stations offer
fuels posted as Regular with an
octane rating below 87, particularly
in high altitude areas. Fuels with octane levels below 87 are not
recommended. Premium fuel with an octane rating of 93 or higher will
provide improved performance and is recommended for severe duty or
high performance usage
A video of dyno runs from CJ Pony Parts with a stock ST using 87 octane, then 93 octane was done.
The output was identical (both HP and torque) up to 5,500, then a drastic cut in power and torque from 5,500 upwards with only 87 octane.
The graph has a line straight down atthe dip point.
So the engine is protecting itself at the 5,500 mark by lowering something, on the 87 diet.
link: https://www.youtube.com/watch?v=RzyBUzFumhY
So... If you never run the engine over 5,500 rpm you would not see a single bit of diffference in power.
So for a daily commute where you are not running the rpm way up, 87 gas is fine.
Curiously on my prior 2012 Focus SE, I found 93 octane made a diffeerence all around, even off idle the engine was better. But that was with 12:1 compression..
I have started using 87 octane while I am breaking in my 2 week old ST. Kinda hard to go racing in snow... LOL
Exactly. I Always wonder why some car owners will cheap out on their gas and oil, but think nothing of dropping big $$$ on an I-phone or such. A car is an expensive investment. Treat it right.I just ask myself, "will $3.00 more per fill up kill me, will $5?"
Nope. Premium is good for the St engine.I was more or less asking if premium would harm the engine due to the higher octane and higher combustion temp.
I don't want to do anything to harm my less than a week old ST.
You would not harm the car in any way shape or form. In fact it's required to run premium fuel to get the maximum performance out of the stock calibration.I was more or less asking if premium would harm the engine due to the higher octane and higher combustion temp.
I don't want to do anything to harm my less than a week old ST.
If anything, advanced ignition timing will lower exhaust gas temperatures.I was more or less asking if premium would harm the engine due to the higher octane and higher combustion temp.