Turbo Engine Power and Octane

According to Mazda themselves, this turbo 4 cylinder makes 227hp on regular octane and 256hp on premium.
I have previously heard similar claims about other modern turbo charged cars.
Most of the "experts" and online opinions claim that moving to a higher octane will not make more power.
I understand the argument. Higher octane does not contain more chemical energy, it just burns slower and is harder to ignite accidentally. So why use it if required?
Well, the only thing I've found suggests that the computer is able to use it's sensor to change the timing and maybe other settings.
So Mazda 2.5t goes from 227hp to 256hp
>+29hp or 13%

So the question is, how does this translate to a 1.5L Ecoboost?
I'm trying to find a chart I found from Ford (I think) that said 1.5L takes 87oct and then for the 2.0L it says 87oct (91oct recommended). So why would it be recommended for the 2.0L despite 87 being fine but then that not be the case for the 1.5L? This makes no sense to me.

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  1. 4 weeks ago
    Anonymous

    >harder to detonate fuel
    >able to shove more of it into a combustion chamber before it ignites
    That's the general idea, for both turbo or N/A tuned setups.
    Race fuel is really hard to detonate at 100+ octane and those cars and bikes go plenty fast.
    Know what NO2 does? Replaces air with inert gas that also doesn't detonate allowing you to shove more fuel and air into a confined space before it detonates.

    • 4 weeks ago
      Anonymous

      Thank you. I do get that. I'm asking about non-tuned cars making different horsepower just by filling them with a different octane. If a car has knock sensors and can change the timing and also use the MAP sensor or something to flip the ECM over to a different air fuel mixture, that would be inline with what you are saying and what Mazda is claiming. I do know you are correct and I do believe Mazda. However, multiple people on this board have called me moronic for thinking that higher octane gas can get you more power and the claim only ever seems to be made regarding turbo charged engines. Why would that be if there is no active system controlling the turbo?

      What I really want to know, which I have not found, is whether or not a 1.5L ecoboost will make more power on higher octane gas.

      • 4 weeks ago
        Anonymous

        My twenty year old honda can sense low octane gas and slows the timing down to keep early detonation from happening.
        So it doesn't get more maximum power from high octane, but it definitely loses power from low octane.
        I have no clue how a modern system does any of it but I imagine it's not terribly more complicated of a concept in newer cars or turbo ones.

      • 4 weeks ago
        Anonymous

        Basically any semi-modern car with some kind of MAF, knock sensor and a computer control can "tune" itself to a certain extent for environmental conditions. Like other anon said, higher octane fuel simply raises the ceiling for engine knock to happen and allows the timing to increase more, which makes more power. Naturally aspirated engines are susceptible to this too but the effect is less significant than in forced induction, since turbos/superchargers run very hot and at high pressures.
        FYI the Mazda 2.5 turbo calls for 93 octane to get the maximum 256hp/320hp, not just 91 so its pretty likely that's an accurate increase.
        I just bought a CX-50 turbo the other week, the dealer cheaped out on me and filled it with 87 though. Going on a small trip this weekend so if I can find a couple places with 93 to stop on the way I'll try it out and see if the difference is noticeable.

        • 4 weeks ago
          Anonymous

          I like it anon.

          • 4 weeks ago
            Anonymous

            thanks anon. Its mostly a commuter for my fiance/trip vehicle but it's pretty nice so far.

            >93 octane specifically, which is not as common as people think
            Where I live you have to go out of your way to find 91, and 93 is "premium"

            Huge majority of places, especially the more dense population areas, only have 91 unless you want to drive 40+ miles and pay a huge markup lile $5/G instead of $3.50.

            [...]
            These oem turbo engines usuaply dont have a computer controlled adjustable wastegate, so yes they can control boost based on the knock sensor by limiting the throttle. Your throttle/intake is what is allowing air to flow to the exhaust, so this is a quite easy way to control boost based pn combustion quality.

            You can also fill up with 91 and throw in some octane booster to get to 93. 93 octane is somewhat uncommon in some areas but every walmartor O'Reilly's has octane booster

        • 4 weeks ago
          Anonymous

          Were you the guy that got the sick deal on the cx50 in some other thread? Something like $35k all in?

          https://i.imgur.com/uajDQYS.png

          According to Mazda themselves, this turbo 4 cylinder makes 227hp on regular octane and 256hp on premium.
          I have previously heard similar claims about other modern turbo charged cars.
          Most of the "experts" and online opinions claim that moving to a higher octane will not make more power.
          I understand the argument. Higher octane does not contain more chemical energy, it just burns slower and is harder to ignite accidentally. So why use it if required?
          Well, the only thing I've found suggests that the computer is able to use it's sensor to change the timing and maybe other settings.
          So Mazda 2.5t goes from 227hp to 256hp
          >+29hp or 13%

          So the question is, how does this translate to a 1.5L Ecoboost?
          I'm trying to find a chart I found from Ford (I think) that said 1.5L takes 87oct and then for the 2.0L it says 87oct (91oct recommended). So why would it be recommended for the 2.0L despite 87 being fine but then that not be the case for the 1.5L? This makes no sense to me.

          Thank you. I do get that. I'm asking about non-tuned cars making different horsepower just by filling them with a different octane. If a car has knock sensors and can change the timing and also use the MAP sensor or something to flip the ECM over to a different air fuel mixture, that would be inline with what you are saying and what Mazda is claiming. I do know you are correct and I do believe Mazda. However, multiple people on this board have called me moronic for thinking that higher octane gas can get you more power and the claim only ever seems to be made regarding turbo charged engines. Why would that be if there is no active system controlling the turbo?

          What I really want to know, which I have not found, is whether or not a 1.5L ecoboost will make more power on higher octane gas.

          Higher octane can get you more power IF YOUR COMPUTER IS MAPPED FOR IT.
          When manufactueres give two ratings like your OP, it means the map was tuned for regular octane parameters and high octane parameters.
          You can run regular on a high octane only car, but itll be running off guesswork based on the original map
          >Reduced power
          You can run high octane on a regular octane car, but it wont advance anything beyond what it was mapped to do
          >No gains in power

          I dont think manufacturers alter boost mapping much. Ignition timing generally provides the most significant changes to power

          • 4 weeks ago
            Anonymous

            >Were you the guy
            Yeah little under $34k including dealer fee, '24 turbo meridian trim w/ 7k miles. Wasnt originally planning to spend that much but it really wasnt much more than other used higher mileage '23 models we'd been looking at and CPO's come with a power train warranty extended out to 100k mi anyway. Not that I think they are a bad value for MSRP, they do have a decent amount of standard features (all CX-50's are AWD, have all the safety features, carplay/android auto, radar cruise, and then the turbos all have power passenger & driver seats, seat memory, sun/moonroof).
            18" wheels should be standard on the turbo models instead of the 20" imo so glad I found a meridian edition. The 20's are noticeably less comfortable cause of the thin sidewalls, Chip Foose and his consequences have been a disaster for passenger car comfort. If not for the meridian edition wheels I would have asked the dealer to swap the 20's with a base model's 17's or something

        • 4 weeks ago
          Anonymous

          I have a dealer trying to push me on a turbo 50. Anything I should know before a test drive?

          • 4 weeks ago
            Anonymous

            A test drive will probably tell you all you need to know. The 50 is a streched CX-30, doesn't share a platform with the CX-5, so it has torsion beam rear suspension though it drives pretty well. Its wider, longer, and more ground clearance than a CX-5 but the roofline is lower. The rear cargo area is thus longer and wider, but not as tall so on paper you lose some capacity. 20" wheels are standard for turbos so like I said in the other post the ride quality suffers a bit. Its a bit firmer and flatter than the CX-5 though still pretty comfortable imo. Apparently some people complained about it being too firm and the steering too stiff, felt fine in '23 models I drove so whatever but starting in november '23 production ('24 model year) they have slightly softer suspension tuning and slightly lighter steering. Only thing thats mildly disappointing so far is the gas mileage - not terrible but not great, getting about 23-25 mixed driving. The power is pretty good makes 310 ft/lb on the cheap gas and its a twinscroll turbo so there's good torque above 2k rippems. Definately happy with it over the n/a 2.5. I'm not anticipating too many longevity issues hopefully, this engine has been out with Mazda in different versions for almost 10 years now. All turbos have the panoramic sunroof which is new to mazda, but there havent been issues like VW. The sun roof itself looks pretty big in person but actually only opens a small amount. The seatbelt chime is kind of annoying, the console cup holders wont hold a big thermos, rear passenger doors are a bit plasticy. Otherwise cant complain about anything really

          • 4 weeks ago
            Anonymous

            To add -
            The trim levels overall are mildly confusing, the turbo engine models are basically their own trim rather than just an engine option for any trim. So the "base" turbo has the features of the n/a 2.5 "premium plus" trim, except it DOESNT have bose speakers, power side mirrors, heads up speedo projection, or cooled seats (though they are heated). To get most of those options back you'd have to get the turbo premium trim, except for heads up projection with is only on premium plus, which also has the 360 camera and heated rear seats. For US trims anyway Canada has slightly different trims too
            Apart from the trim differences all turbo models have a couple things that the n/a trims do not - adaptive (lights turn with corners) projector LED headlights, full LED tail lights, and paddle shifters.
            Then the "packages" are their own thing; weather package comes with seat back/cargo bay liners and all weather rubber floor mats, cargo package has the cargo area cover and some other shit, roadside assistance package has an extra roadside kit (all models have a spare tire, jack and basic wheel change items though), towing package includes a tow hitch and harness, then the apex package I think is only for meridian trim and includes mud flaps and a roof platform.

          • 4 weeks ago
            Anonymous

            I think the cx-50 is pretty cool but I will the meridian trim is mostly cosmetic. You don't get more ground clearance and you don't more under body protection. Functionally, all you really get is more off word oriented tires. It's also not that fast, 0-60 in 7 seconds, iirc. I might not know.
            What I do think you get is a well made car that's good enough for service streets and with more presence than a lot of it's competitors. It probably drives nice. I like the cx-50 but haven't owned one. I did have a Mazda 3 a few years back and it was great.

            Really look up all the differences between the
            trim levels.
            Really look at the competitors.

          • 4 weeks ago
            Anonymous

            I completely forgot to talk about the "meridian edition" trim; yes it is entirely cosmetic. Literally just wheels/tires w/ black lug nuts, hood decal, and rocker panel trim. Everything else is exactly the same as the regular turbo. The CX-50 is by no means an "offroader" and you will be disappointed if you go into it expecting such. The awd is mostly for the 3,500 lb tow capacity and dirt/gravel/rain traction. Not a true full time awd like subaru. It is fairly reactive for what it is, it always kicks in when you'd expect it to (which is most of the time if you aren't coasting/driving very gingerly). Overall it drives somewhere between a car & SUV.
            yeah 0-60 is 6.9 sec or something like that. Not slow not fast, good for passing or on-ramp merging due to all the torque. If you're looking for a faster vehicle there are other options in the range that have more outright usability and/or get better fuel economy, but they don't look as good and the interiors aren't as nice for similar price range imo. We only actually test drove some subarus & jeeps cross shopping, of which the CX-50 wasn't necessarily the comfiest (still very comfortable by my standards) but was the nicest to drive.

          • 4 weeks ago
            Anonymous

            99% of AWD use, in the real world, is for snow and the cx-50 AWD is great for that. It passed TFL's 3 wheels on rollers test which not all AWD cars do. So, it should be great on snow and forest service roads to. So, I'm in no way knocking it I'm just saying, functionally vs the others trims, Meridian gets you tires and some body molding. I didn't mean to suggest it wasn't good, though obviously not a rock crawler. The only thing that surprises me is they didn't give it drive modes?

    • 4 weeks ago
      Anonymous

      >no2
      >inert gas
      someome didnt do their homework
      no2 is "inert" but the moment something happend it release its o2 part from the n giving you a very non-inert shitload of oxygen to burn the extra fuel you add.
      it makes no power to show more fuel in unless you add more o2 to combust it and thats what the no2 does in an "inert" way, if you just added pure o2 you would blow up your engine its way to reactive, would probably ignite in the intake.
      so you are right but so fricking wrong at the same time.

    • 4 weeks ago
      Anonymous

      dumbass

    • 4 weeks ago
      Anonymous

      moron, nitrous oxide is an oxidizer. It's the oxygen in the mix that makes the power. The only reason there's nitrogen in it is because pure oxygen is too volatile. Shit you could probably get away with Ar2O2 if you really wanted.

  2. 4 weeks ago
    Anonymous

    Higher octane fuel lets you push compression and timing more aggressively without getting knock. The 2.0L is likely tuned such that detonation is more likely with 87 octane.

    • 4 weeks ago
      Anonymous

      For a non turbo engine you gain the most important power: power UNDER the curve, when using 91 octane when it's hot out.

      Mazda rates the 2.5t for 250hp with 93 octane specifically, which is not as common as people think. 25ish HP for 6 octane points is roughly correct as an octane point is good for an extra .33-.5 PSI depending on where we are in the air temp and timing map range.
      140HP na engine on 12lb boost should be good for ~225hp, 2-3PSI more would give 248-255hp

      So that is what is is

      Are you saying the car can change boost in real time based on octane? I didn't think that was possible. The only car I know of with variable compression was the Nissan a few years back and that seemed like a gimmick.

      • 4 weeks ago
        Anonymous

        You can buy a boost controller for many European cars and it will work backwards to achieve a boost pressure. Boost changes are actually easier than timing changes

      • 4 weeks ago
        Anonymous

        You don't need variable compression, just adjust the wastegate position dynamically for more or less turbo speed. Octane sensors exist, so you'd just need to map out the maximum boost for a given octane level and adjust based on that.

        • 4 weeks ago
          Anonymous

          Okay, this makes sense to me.
          Hmm, clearly Mazda has this.
          Wish I knew how to figure out if my 1.5L Ecoboost does or if it's only on the 2.0 for example.

          • 4 weeks ago
            Anonymous

            Google says the 1.5 Ecoboost has an electronic wastegate. The stock engine tuning is almost certainly not going to run higher than advertised boost, but an aftermarket tune could probably take advantage of that. Most turbo engines use electronic waste gates these days

          • 4 weeks ago
            Anonymous

            The boost mapping can absolutely be done by a competent tuner. Every car nowadays is equipped with knock sensors, so most already have a "fallback" tune that gets used when they detect bad things are happening inside the engine.

            Thanks

          • 4 weeks ago
            Anonymous

            The boost mapping can absolutely be done by a competent tuner. Every car nowadays is equipped with knock sensors, so most already have a "fallback" tune that gets used when they detect bad things are happening inside the engine.

  3. 4 weeks ago
    Anonymous

    i don't really know where to start itt

  4. 4 weeks ago
    Anonymous

    Couple things:
    Knock sensor are pretty good nowadays allowing the computer to have dynamic timing
    running on a lower octane than recommended will result in the computer pulling bulk timing and the engine running inefficiently
    I'm pretty sure the horsepower figure manufacturers give you has to be at the octane rating they recommend, so if they say 91 recommended even though it can still run on 87 that's because they want to quote the power figure on 91. If they say 87 or higher recommended, but the engine till makes more power on 91, that's because they want poors to feel comfortable buying their entry level car.

    You can see this a lot with Toyotas and Lexus cars which have the same motor - premium lexus will recommend a higher octane rating and quote a higher power figure.

  5. 4 weeks ago
    Anonymous

    >running anything other than premium in a turbo car

    >Shiggydiggydoo

  6. 4 weeks ago
    Anonymous

    When gasoline is agitated, oxygen becomes dissolved in it and the octane raring is lowered.
    The farther a gasoline tanker has to travel (bouncing down the highway) the lower the octane rating for the fuel is by the time it transfers to the gas station- thus why pumps say "minimum" octane, they figure "well, it shouldn't be any lower than X by the time it gets to this station"
    So if you live near a refinery you'll see 93 at all the stations.
    If you live 500 miles from the nearest refinery, all the stations will have 91 listed.
    That was identical fuel when it left the refinery.

    • 4 weeks ago
      Anonymous

      Interesting

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