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I recently moved to AZ and noticed there is only 91 octane gas at every station. I was wondering if mixing 100 octane gas will actually provide a significant improvements in performance? I don't know enough about engineering and the M177 engine.
Or to make it simple, if someone knows a gas station in the Phoenix area with 93 octane 😂
I recently moved to AZ and noticed there is only 91 octane gas at every station. I was wondering if mixing 100 octane gas will actually provide a significant improvements in performance? I don't know enough about engineering and the M177 engine.
Or to make it simple, if someone knows a gas station in the Phoenix area with 93 octane 😂
Thanks for the help!
US engines are all tuned for 91, since that's the max you'll find in many states. AZ is a 91 state so I doubt you'll find 92 or 93. Unless you have a tune that changes the ECU maps, 100 won't make a difference. Does the 91 feel different than the 93? If so, and you're sure your not imagining it, you can try some, but it would be very strange that a US-tuned engine would leave it to the knock sensors to alter mapping on 91.
2020 E63s Wagon, 2012 C63 AMG Coupe, 1989 560SL, 2023 911 Carrera T
fwiw, my w204 was tuned for 93 gas when i lived in MA. I am in CA now where we only have 91 and I have not run into any issues with the tune so far. I dont expect to lose much if at all with the w205 stock tune on 91
Just run 91. There's likely no difference. These engines have so much headroom left even on 91 I highly doubt it's pulling any timing or boost relative to 93.
I see this on my 2019 C63S fuel filler cap. I'm in California, a 91 state for premium gas. Doesn't this mean that all C63 and C63s vehicles sold in the US (at least with MY2019) would have be tuned for 91 octane?
I tried 100 octane from Sunoco when my C was stock. I felt a difference in pulling power and seems to pop and bang a little more. Maybe it was the placebo effect🤷🏻*♂️
There's no way any positive power difference you noticed immediately was actual. That's not the way these ECUs work. If the car was reducing dynamic timing advance due to feedback knock (it probably wasn't on 91), it would slowly advance the timing again with a lack of noise on the new fuel. In all likelihood, 100 octane will make less power on the stock tune than 91 or 93 because the timing is sub-optimum and the burn isn't quick enough to maximize torque. You may have experienced more pops and bangs due to unburnt fuel when the exhaust valves open.
The July issue of Car and Driver has a good article of octane and how much power increase with different available fuels.
A stock M5 dynoed at 604 RW HP with 91 octane and 617 with 93 and knocked ( .1) sec off the 0-60 and quarter mile times. Way under rated as this car is supposed to be 617 at the crank.
A Ford F150 with a 450 HP V6 added 20 HP going from 87 to 93. It came in at 380 HP with 93 and if you use a 15 % drive line loss that would be 447 at the crank --so rated about right.
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