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Regular vs premium ???

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  • Regular vs premium ???

    Switching from 87 octane to 93 octane in a turbo 2.0 litre and my computer Ecu changes for fuel changes What do you think should I change for more power ?
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  • #2
    That's not quite how it works my dude;

    A car is tuned for a certain octane, and from there, there are sensors that will protect the engine.
    Mainly, Knock and Primary o2.

    Basically, if you give a car the fuel it wants, then it will run as it was tuned, seeing no knock, and no harmful emissions.
    If you give it less than it was tuned for, it'll "learn" that your fuel is bad, from the knocking, and retard your timing, or limit boost.

    There's no magic way to test octane in a running car, so there's no way for an ECU to do BETTER than it was tuned for.
    Basically, if the manual says run on 87, putting 89 in it won't help.

    Even when using an enthanol content sensor on E85 cars, the octane is different depending on what crop the ethanol came from (Australia's is PARTICULARLY good), so just because it sees 85% ethanol, doesn't mean it knows the octane.

    If the fuel TYPE is the same, you can safely ignore any numpty who claims that "My car runs so much better on premium!" if it was designed around regular.

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    • #3
      So Hyundai Sonata 2.0t Limited running 87 octane a turbo car that runs on regular gas 278hp but if I fill it with 91 or 93 octane fuel I pick up 10hp on the Dyno with out doing any thing but change the octane level I’m confused now in my owners manual it requires 87 or higher octane but the engineers test the engine with 93 shell V power With about 290 hp. No computer changes the computer still thinks that it’s running regular fuel the car just responds with more power doing Smokey burnouts In 1 gear with my flappy paddles In my Fwd family sedan . Down 72anD street where gas is so cheep right now they pay me to take gas .
      Last edited by Skullinhand; 17-05-2020, 06:29 PM.

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      • #4
        International margin of error allowed on a Hub dyno (5%).
        Roller Dyno's, have approximately a 10% margin of error, and have a HUGE list of tolerances that no operator ever checks (I promise).

        With your gain being 3.4%, I'd wager something like warmer tires after the first run, perhaps a breeze blew past and gave you some cooler intake air, perhaps the Dyno's gear oil is worn, and gets 'happy' after the first run. There are literally hundreds of variables that could result in a 3.4% power difference.

        Even if you enjoy the story of "Car goes better on X", you don't need to believe me, that's fine, but I'd be taking it back to whomever tuned it and DEMANDING their qualifications if they were only able to get 3.4% out of a car, tuning between regular and premium; usually a jump with 1:1 parts is about 7%, absolute bare minimum in a 2L 4 banger.
        Last edited by Master_Scythe; 17-05-2020, 06:38 PM.

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        • #5
          I was kinda hoping that this topic is about pornhub.
          1982 Ford Taunus

          1984 Ratty Oldsmobile Custom Cruiser

          1963 Oldsmobile Super 88

          1974 Chevrolet El Camino

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          • #6
            Originally posted by SBC View Post
            I was kinda hoping that this topic is about pornhub.
            Did you use your free month during the lockdown?
            I swear, when you're free, all the premium videos look golden.
            When you're premium, they dont show up in your searches.
            Such is life :P

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            • #7
              Originally posted by Master_Scythe View Post

              Did you use your free month during the lockdown?
              I swear, when you're free, all the premium videos look golden.
              When you're premium, they dont show up in your searches.
              Such is life :P
              No I didn't use it yet, it still says it's free.
              1982 Ford Taunus

              1984 Ratty Oldsmobile Custom Cruiser

              1963 Oldsmobile Super 88

              1974 Chevrolet El Camino

              Comment


              • #8
                Originally posted by Skullinhand View Post
                So Hyundai Sonata 2.0t Limited running 87 octane a turbo car that runs on regular gas 278hp but if I fill it with 91 or 93 octane fuel I pick up 10hp on the Dyno with out doing any thing but change the octane level I’m confused now in my owners manual it requires 87 or higher octane but the engineers test the engine with 93 shell V power With about 290 hp. No computer changes the computer still thinks that it’s running regular fuel the car just responds with more power doing Smokey burnouts In 1 gear with my flappy paddles In my Fwd family sedan . Down 72anD street where gas is so cheep right now they pay me to take gas .
                Sorry, late to the threads.

                So, the engine is set up to use 93 Shell V Power, if what you said is true. If it was developed on 93 Shell VPower, however it'll be tested with 87 as well...

                Your ECU will be set up with a correction factor built in, this is what determines your minimum octane.

                Without a corerction factor, you're probably experiencing knock running on 87, the ECU simply adjusts the timing and fuelling to compensate as that'll be within its correction factor parameters. When you put in 91 or 93 the knock is clearly less apparent and the ECU no longer needs to apply much or any correction factor to your ignition table or fuelling tables. Obviously an OEM ecu has emissions to consider, so it can't simply keep adding fuel to reduce knock as emissions get worse with too rich or too lean conditions, so it'll be pulling timing as well. The timing being pulled back will be where your "loss" of power is.

                Unsure why a manufacturer would set up a car this way for a US model, knowing regular is 87 and not 93.

                Could easily be an error in the dyno, as pointed out. However doing back to back runs with different fuel on the same dyno with the same operator takes most of this out. You might not get the 290hp but you'll see the difference in power delivery (10hp or whatever).

                Plotting the actual ignition advance against rpm at WOT with both fuels would show you the difference. It could be the timing can be more aggressive at low rpm on 93 which is maybe why you think it feels like it has more torque.


                tldr; not enough info, could be dyno error.
                I stripped my car out so much it now has 49/49 weight distribution.

                Project Diesel Tune:

                https://forums.mightycarmods.com/for...ct-diesel-tune

                My new Daily HA36S Alto Works

                Martin's Kei to success

                https://forums.mightycarmods.com/for...uki-alto-works

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                • #9
                  Originally posted by MHR1294 View Post
                  Unsure why a manufacturer would set up a car this way for a US model, knowing regular is 87 and not 93.

                  Could easily be an error in the dyno, as pointed out. However doing back to back runs with different fuel on the same dyno with the same operator takes most of this out. You might not get the 290hp but you'll see the difference in power delivery (10hp or whatever).
                  Don't forget the difference between Ron\Mon and AKI (I don't think you did; just a reminder for anyone reading the thread).

                  I thought on this a lot in bed, and the only thing i could come up with, was that it's possible the 'minimum' recommended is just that, a bare minimum.
                  Lets assume that the Dyno is accurate; even thought 3% is well within all manufacturers margin of back to back error.

                  What I suspect is that it's been 'knife-edge' tuned, at 87AKI.
                  Basically, there is nearly zero knock, except where the high-load cells are in action.
                  This will be 'minor knock', is unlikely to damage anything (within the warranty period...) and will result in the knock sensor doing it's job, and pulling timing, but only up very high.

                  This would ensure very good fuel economy, nice 'zip' for a small car, and not cost hyundai a cent, so long as it lasts past warranty.

                  Without the OP's dyno graphs, we can't be sure, HOWEVER, I expect a 1:1 graph, up until 75% of his rev range, or power band; and only then will a 10hp difference creep its way in.

                  The fact that the OP says "91 or 93" (AKI) is a bit telling also; lending itself to my theory.
                  It seems like 91 meets the requirements, and 93 is overkill, adding no benefit.


                  There are maintenance factors here also; while a power run SHOULD be on open-loop fuel maps; some economy cars have a max correction factor on fueling (short term fuel trim); or even more confusing, a max fuel correction speed (0.25% per second, or such).
                  I've seen a few modern cars that only go semi-open-loop, and still modify maps at full throttle (k20 Hondas are notorious for it, because their Primary sensor is a true wideband; so why disable it?).
                  What I'm getting at, is that there's also a chance that fueling is lean (or even has a lean burn feature!) and at full power, is knocking.

                  Or perhaps the MAP sensor is a dud, or just 0.1bar out or some such? Meaning the boost reference the ECU is seeing is 0.1bar lower, than what it really is?

                  There are just so many factors; at the end of the day, you're not going to feel 3% outside of placebo.
                  If it were my car, I'd run 91 AKI, just because I suspect something is going on at the 'recommended' fuel level, but there's no way I'd waste money on 93 AKI when the book says 87. Thats just idiocy.

                  Like people in Australia who run 98Ron in their 91Ron tuned cars!
                  If you even know the difference in formulation, 95Ron has the same low sulfur and higher cleaning additive requirements; you're literally wasting cash going from 95 to 98! Uneducated fools.
                  Last edited by Master_Scythe; 27-05-2020, 03:02 PM.

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                  • #10
                    Yeah I did remember the US uses AKI. They actually print the formula on their pumps (Ron+Mon/2)

                    We use just Ron in the UK. Japan also uses RON - which is an important fact the jap car fanboys forget. Regular in Japan is 90 RON! My Kei Car is designed to run on 90 Ron and it's turbocharged. Knock is definitely an issue with this car in boost, because on monitoring the wideband sensor, the lambda read drops to nearly 0.7 when in boost!! I can only assume this is an attempt to reduce the cylinder temps because that's excessively rich. There's even a layer of soot in the exhaust (this is a 2016 car!) I'd like to verify this with an external wideband, as it just doesn't sound right.

                    Normal driving it's about 0.98-1.02 range.

                    However, out of interest I put 99 Ron into the tank, the car made 67hp on the dyno instead of 64 that it's limited to. The car is MAP sensor based, and the air filter has been changed. plus the inaccuracy of the dyno you can safely say it's gained no power at all. that's with an increase of 9!
                    I stripped my car out so much it now has 49/49 weight distribution.

                    Project Diesel Tune:

                    https://forums.mightycarmods.com/for...ct-diesel-tune

                    My new Daily HA36S Alto Works

                    Martin's Kei to success

                    https://forums.mightycarmods.com/for...uki-alto-works

                    Comment


                    • #11
                      You might have 'unlocked' some power, because the knock sensor is now doing zero.
                      Though, 95Ron would probably be enough to achieve that.

                      There's a common misconception that 100RON is everywhere in japan; but that's not the case outside the CBD of each area.
                      Only things we call 'hero' cars are actually tuned for 100Ron; though I believe their normal 'premium' is 97Ron, not 95.

                      IIRC (been a few years since I was over there) Japan usually goes: 90, 94(?), 97, 100? (someone will correct me)
                      Australia is 91, 94(E10), 95, 98.

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                      • #12
                        Originally posted by Master_Scythe View Post
                        You might have 'unlocked' some power, because the knock sensor is now doing zero.
                        Though, 95Ron would probably be enough to achieve that.

                        There's a common misconception that 100RON is everywhere in japan; but that's not the case outside the CBD of each area.
                        Only things we call 'hero' cars are actually tuned for 100Ron; though I believe their normal 'premium' is 97Ron, not 95.

                        IIRC (been a few years since I was over there) Japan usually goes: 90, 94(?), 97, 100? (someone will correct me)
                        Australia is 91, 94(E10), 95, 98.
                        That's possible, but unlike other Kei cars, my car makes maximum boost at 2500 (15psi), and the ECU immediately pulls boost back, it's only about 3psi near the red line to keep it under 64hp (or 67/8 in my case hahaha)

                        Think that sounds about right, I've a friend who still lives in Japan.

                        Japanese regular is Ron 90 minimum, premium minimum starts at 95 Ron. I've no idea about the higher grades

                        We don't have non premium in the UK. By law, our "Regular" is 95 RON minimum. Common grades are 95, 97, 98 and 99. There's a few stations that sell 102 but only near race venues.

                        The 99 Ron I use has 5% ethanol, although I think that was increased to 10% a while ago.

                        How much do you pay for 95 and 98 in Aus?

                        At the moment, we're paying equivalent of 1.90AUD/litre for 95 Ron.
                        I stripped my car out so much it now has 49/49 weight distribution.

                        Project Diesel Tune:

                        https://forums.mightycarmods.com/for...ct-diesel-tune

                        My new Daily HA36S Alto Works

                        Martin's Kei to success

                        https://forums.mightycarmods.com/for...uki-alto-works

                        Comment


                        • #13
                          Pre COVID was about:
                          $1.50 a litre for 91
                          $1.60 a litre for 95.
                          $1.80 a litre for 98.
                          Those prices fluctuate by about 25c, depending if you purchase at the start of the week, or the end of the week.

                          With covid, we're seeing about:
                          90c a litre for 91
                          $1.20 a litre for 95.
                          $1.50 a litre for 98.

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                          • #14
                            Originally posted by Master_Scythe View Post
                            Pre COVID was about:
                            $1.50 a litre for 91
                            $1.60 a litre for 95.
                            $1.80 a litre for 98.
                            Those prices fluctuate by about 25c, depending if you purchase at the start of the week, or the end of the week.

                            With covid, we're seeing about:
                            90c a litre for 91
                            $1.20 a litre for 95.
                            $1.50 a litre for 98.
                            hory shet, okay so we pay about 45-60% more per litre than you.

                            I'm in the wrong country.
                            I stripped my car out so much it now has 49/49 weight distribution.

                            Project Diesel Tune:

                            https://forums.mightycarmods.com/for...ct-diesel-tune

                            My new Daily HA36S Alto Works

                            Martin's Kei to success

                            https://forums.mightycarmods.com/for...uki-alto-works

                            Comment


                            • #15
                              Most fuel around here is made either on-shore, or imported from Taiwan or Malaysia; whom we have trade agreements with.
                              It WAS cheaper, before the government took away the 8c per litre fuel subsidy.

                              I hate how governments go all or nothing.
                              Why not just halve it?

                              It's like sugar free drinks.
                              I don't entirely trust Sweetener 951 in concentration; but I also don't like the idea of assloads of refined sugar; yet those are my two options.
                              Why can't I get a 50/50 split? (I mix my own; but I shouldn't have to).

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