Page 2 of 5 FirstFirst 1234 ... LastLast
Results 11 to 20 of 44

Thread: Does using Premium gas have any negative effects? (2015 CVT ES)

  1. #11
    Moderator
    Join Date
    Jul 2015
    Location
    Mitsu
    Country
    United States
    Posts
    1,359
    Garage empty: add car
    Thanks
    256
    Thanked 315 Times in 246 Posts
    Quote Originally Posted by Cobrajet View Post
    Minimum here in the States is 87, maximum octane available is generally 92-95 depending on where you live.

    The Mirage manual for the US states that the car should be run on a minimum of 87.
    In mid-west states it is downgraded to 85 due to altitude, and we are using R+M vs RON overseas. RON is usually 8-10 points higher then MON, so the difference is 4-5 points.

    I am wondering if US model has lower compression ratio than overseas.


        __________________________________________

        click to view fuel log View my fuel log 2015 Mirage DE 1.2 manual: 46.4 mpg (US) ... 19.7 km/L ... 5.1 L/100 km ... 55.7 mpg (Imp)


  2. #12
    Moderator inuvik's Avatar
    Join Date
    May 2015
    Location
    Coos Bay, OR
    Country
    United States
    Posts
    3,835
    Thanks
    4,761
    Thanked 1,562 Times in 1,120 Posts
    Quote Originally Posted by cyclopathic View Post
    In mid-west states it is downgraded to 85 due to altitude, and we are using R+M vs RON overseas. RON is usually 8-10 points higher then MON, so the difference is 4-5 points.

    I am wondering if US model has lower compression ratio than overseas.
    Compression ratio for the UK models is 11:1 compared to the USA's 10.5:1

        __________________________________________

        click to view fuel log View my fuel log 2015 Mirage ES 1.2 automatic: 40.5 mpg (US) ... 17.2 km/L ... 5.8 L/100 km ... 48.6 mpg (Imp)


  3. #13
    Moderator
    Join Date
    Jul 2015
    Location
    Mitsu
    Country
    United States
    Posts
    1,359
    Garage empty: add car
    Thanks
    256
    Thanked 315 Times in 246 Posts
    Quote Originally Posted by inuvik View Post
    Compression ratio for the UK models is 11:1 compared to the USA's 10.5:1
    That would explain knocking, since our 87 =~91-92 RON.

    I wonder if MPG on Premium vs Regular would be better? engine has a knock sensor, so in theory it can advance timing more with premium.

        __________________________________________

        click to view fuel log View my fuel log 2015 Mirage DE 1.2 manual: 46.4 mpg (US) ... 19.7 km/L ... 5.1 L/100 km ... 55.7 mpg (Imp)


  4. #14
    Junior Member
    Join Date
    Nov 2015
    Location
    Florida
    Country
    United States
    Posts
    2
    Garage empty: add car
    Thanks
    2
    Thanked 0 Times in 0 Posts
    Thanks for the replies everyone.

  5. #15
    Senior Member Ares's Avatar
    Join Date
    Jan 2014
    Location
    Houston
    Country
    United States
    Posts
    1,908
    Thanks
    42
    Thanked 201 Times in 142 Posts
    Quote Originally Posted by cyclopathic View Post
    engine has a knock sensor, so in theory it can advance timing more with premium.
    That's what I was thinking too... And, with that logic, also better performance?

  6. #16
    Senior Member
    Join Date
    May 2014
    Location
    Central NY
    Country
    United States
    Posts
    351
    Thanks
    0
    Thanked 20 Times in 17 Posts
    Quote Originally Posted by Ares View Post
    That's what I was thinking too... And, with that logic, also better performance?
    Absolutely. But ... how much? Probably not enough to really notice it much.

    I think the advantage would be the ability to run it a bit warmer with a grille block and avoiding spark knock and using premium gas to keep the timing advanced more while hot.

  7. #17
    Moderator
    Join Date
    Jul 2015
    Location
    Mitsu
    Country
    United States
    Posts
    1,359
    Garage empty: add car
    Thanks
    256
    Thanked 315 Times in 246 Posts
    Quote Originally Posted by Ares View Post
    That's what I was thinking too... And, with that logic, also better performance?
    It is hard to tell. Get Elm327 reader, Torque app and do some testing. It is really engine specific, on some engines big difference on others none.

    I have tried premium on Prius C and there was modest MPG gain, but not enough to compensate higher cost. Changes were marginal at best within error range.

        __________________________________________

        click to view fuel log View my fuel log 2015 Mirage DE 1.2 manual: 46.4 mpg (US) ... 19.7 km/L ... 5.1 L/100 km ... 55.7 mpg (Imp)


  8. #18
    Senior Member Ares's Avatar
    Join Date
    Jan 2014
    Location
    Houston
    Country
    United States
    Posts
    1,908
    Thanks
    42
    Thanked 201 Times in 142 Posts
    Quote Originally Posted by cyclopathic View Post
    It is hard to tell. Get Elm327 reader, Torque app and do some testing. It is really engine specific, on some engines big difference on others none.

    I have tried premium on Prius C and there was modest MPG gain, but not enough to compensate higher cost. Changes were marginal at best within error range.
    I agree. But when I hear engine sounds worse when using regular, I'll take my chances with high octane.

  9. #19
    Moderator
    Join Date
    Jul 2015
    Location
    Mitsu
    Country
    United States
    Posts
    1,359
    Garage empty: add car
    Thanks
    256
    Thanked 315 Times in 246 Posts
    Try TopTier gas. And yes it sounds alot smoother on premium for sure.
    Quote Originally Posted by Ares View Post
    I agree. But when I hear engine sounds worse when using regular, I'll take my chances with high octane.

        __________________________________________

        click to view fuel log View my fuel log 2015 Mirage DE 1.2 manual: 46.4 mpg (US) ... 19.7 km/L ... 5.1 L/100 km ... 55.7 mpg (Imp)


  10. #20
    Senior Member
    Join Date
    Jan 2016
    Location
    maryland, usa
    Country
    United States
    Posts
    214
    Thanks
    0
    Thanked 50 Times in 35 Posts
    There was a study done in Canada by a Canadian news station where they talk about fuel octane. They took a chevy pos and put it on the dyno with regular, drained the tank, and ran it with premium, and nothing happened between power wise. They then checked how it tested emissions wise and noted that when they put premium in, the car was expelling un-burnt fuel IE the car wasn't taking advantage of said higher octane. I wont go into how dumb the people in said news were including the retard expert they had on.....

    It was a ****ty chevy which I think all american cars are junkers. The biggest problem with american cars are the lack of engineering. The only american cars that can adjust to different fuels from factory are those with flex fuel sensors, aka the ecu is able to tell the difference between 89, 91, 93, and e85, and any ratio mix of both. Even my STI can self adjust to lower octane fuel, granted you lose power and its noticeable. (many subaru sti owners are retards and don't realize the knock sensor helps the ecu retard timing when you use lower octane fuel, you almost never hear of lower octane blowing a motor because most import cars self adjust anyway).

    personally I will be using 93 octane after my first tank of gas is used up, I'm 90% sure the dealer put in regular to top it off, which is no big deal to me. once the tank is nearly empty it will be 93 time.



Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •