Premium gas?

Discussion in 'On The Road' started by ham fam, Sep 21, 2021.

  1. lifespeed

    lifespeed Active Member

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    One thing to keep in mind regarding "auto adjust" for octane is it relies on a knock sensor(s). As good as modern computer algorithms are, knock itself is a nebulous behavior has with hysteresis. One would be well-served to understand this sort of adjustment based on an engine-damaging input (knock) is nowhere near is perfect and reliable as air/fuel mixture control using a knock sensor, which is instantaneous and accurate.

    Engine computer adjustment for fuel grade usually happens more slowly, and is more of a hail-Mary attempt to prevent engine-damaging knock. If one has a turbocharged or high-performance engine that can take advantage of premium fuel, put premium fuel in it! You'll get better fuel economy anyway, negating the additional cost. What, you don't like, paying for premium fuel? I have a simple solution - buy a vehicle that is recommended to run on regular. Most do, easy enough.
     
  2. Patrick w

    Patrick w Active Member

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    turbo motors are generally lower compression motors than NA motors when not under boost. Early knock sensors could only adjust timing- modern systems will adjust timing, adjust valves, control boost levels, etc. Much more than cars from even 15 years ago could do. In the olden days of turbo we used to run lots of fuel to cool the cylinder and prevent detonation. We rarely got good MPG's out of it. Modern systems allow the computer to trim the fuel just below the threshold, and thus, great fuel economy.
     
  3. Patrick w

    Patrick w Active Member

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    Do you mean e85 or e10/15?
    (Dunno maybe you had a turbo stang and I don't mean an svo)
    They do make an ethanol stabil for marine. I use it. I just don't know if it works or not.
     

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