Car and Driver tests high octane on 1.5T

  1. Slickone

    Slickone Senior Member

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    This article was from August, but I couldn't find where it was mentioned here. One of the cars C&D tested was a CR-V with the 1.5T. For it, they said:

    Even as it's sucking down as much as 18.5 psi of boost, the CR-V's 1.5-liter inline-four isn't interested in 93 octane. Honda asks for 87 octane and makes no claims that raising the fuel octane will lift performance. Based on our testing, premium fuel might as well not exist in the CR-V's world.

    We could see this coming. During a similar Car and Driver test 18 years ago, an Accord powered by a 3.0-liter V-6 made more power and accelerated quicker on regular fuel than on premium. The modern CR-V, with half the displacement but rated at just 10 fewer ponies, makes the same argument: don't waste your money on premium. Switching from 87 octane to 93 yielded a 7-hp gain on the dynamometer, but that advantage was lost in the noise at the track. There, the CR-V's zero-to-60-mph and quarter-mile times both tracked a tenth of a second slower on the expensive stuff. While fuel economy at 75 mph ticked up from 27.3 mpg to 27.6 mpg on premium, that's a 1 percent improvement for a 21 percent higher cost.
     
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  2. VarmintCong

    VarmintCong Senior Member

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    Why are they putting 93 in a car that recommends 87?
     
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  3. TypeSiR

    TypeSiR Senior Member

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    Should’ve tested 91 instead. 93 might be a little too high for the ECU to adjust?
     
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  4. tsupersonic

    tsupersonic Senior Member

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    91 isn't available everywhere... In my area, it's 87, 89, and 93.
     
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  5. Zeffy94

    Zeffy94 Senior Member

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    Same. I assume the CTR ECU would probably compensate for 93 instead of only 91 unlike the regular Civics.
     
  6. turbo lover

    turbo lover Senior Member

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    Why would it be unable to adjust for 93? If it was able to run a little more boost and timing because of the higher octane, wouldn't it do so regardless of whether it's 91 or 93?
     
  7. charleswrivers

    charleswrivers Senior Member

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    Yep. Then there are those with the premium recommendation from the factory to allow greater timing advance. There are those that are tuned and would make well less than the tune dyno claims from high k.cont regarding timing. It all depends on what you have.

    On a CRV with a regular recommendation on a factory tune? Yep... 87 makes sense, even if it was shown to make slightly more power on 93. The difference in instrumented tests are so close, the difference seems negligible, though environmental differences in when the tests were performed could have had as much to do with it as octane. Morning vs afternoon runs with a good swing in ambients could negate 7 whp seen on the dyno.

    Any car with a premium recommendation from the factory can use 87 w/o issue and will always be cheaper to operate with it. Any improvements in fuel economy due to running more timing advance won’t offset the large difference in price between 87 and 93.

    I’d only stick to 93 for engine safety when 93 is required (i.e. a car running a TSP Stage 1 tune... or my old Z)... or for 93 if you want a smidge, though possibly unnoticeable amount of additional power on a car with the premium recommendation. It probably won’t really show except under sustained hard driving anyways. K.cont will settle and let you do an occasional stab of the throttle on low octane fuel before climbing and retarding timing.
     
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  8. BriteBlue

    BriteBlue Senior Member

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  9. Jeezer

    Jeezer Senior Member

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    I would regularly agree, but my knock sensor failing on my nissan caused some problems and they go out pretty quickly if you run less than the recommended octane. It's not easy or cheap to fix on most cars so I'm gonna go ahead and say that people should just use what their car calls for.
     
  10. CivilciviC

    CivilciviC Senior Member

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    #10 CivilciviC, Jan 16, 2020
    Last edited: Jan 16, 2020
    Doubtful. The engine is simply just not tuned/designed to handle anything besides 87.
     
  11. CivilciviC

    CivilciviC Senior Member

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    The engine, by design, does not need anything higher than 87. Even if the ECU detects it, it won't advance timing or add boost to compensate. It's likely due to the engine's lower compression ratio- that's what I believe dictates what trim of fuel you need. If your engine is a high compression one and you put in low octane gas, it will pre-detonate and cause engine knock. The computer can adjust for this generally, but results in pulled timing and reduced power output. However, a low compression engine gains nothing from getting better fuel. You won't get early detonation if you use 87. The car won't pull timing. Nothing changes if you go up in octane.

    I don't think it's so much that a high compression engine creates more power on higher fuel trims, but rather, it creates it's intended power output for 93, and then scales downwards from there (if that makes sense). In the case of the 1.5T, it's making it's intended power on 87. You could have less power from lower octane fuel (assuming you could find it), but not more.

    I feel like I'm not explaining this very well, lol. At least I tried, hahaha.
     
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  12. fenix-silver

    fenix-silver Senior Member

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    I don't believe that's what @turbo lover was saying. He was just saying that if a car can max compensate for 91 octane, then if you put 93 octane in it, it will just max out at whatever timing it uses for 91.
     
  13. Gruber

    Gruber Senior Member

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    This article is badly written to make a point. Their actual numbers show that each of these cars, including the CR-V (8 hp not 7?) gained about the same roughly 5% of power by going from 87 to 93. The BMW gained about half of that going from 91 to 93. No surprise. That's exactly what a modern car with a turbo or reasonably high compression and well-working ignition regulation should get.

    This will never be economical if compared to oil companies pricing of premium fuel. But if someone wants badly these additional horses, he doesn't care about 30% more for gasoline or whatever it is. There is really no expectation of the fuel economy increase on premium. Why would it need to increase with more octane?

    As for 0-60 times.... it's a complex issue and C&D doesn't seem to fully comprehend it, although they test cars for a living. It simply does not need to necessarily increase linearly with maximum power, or maximum power-to-weight ratio. The whole power and torque curves count, along with many other factors. It's not so easy or quick to test.
     
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  14. Design

    Design Senior Member

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    #14 Design, Jan 17, 2020
    Last edited: Jan 17, 2020
    The trap speeds speak for themselves. We probably don't need a dyno readout to know that the CR-V's performance improvement is minimal across the entire powerband. By comparison, the F150 saw a pretty significant jump despite marginal peak performance gains. That tells me the majority of improvements are more likely under the curve than above it.

    A better test would have been the Civic Hatch Sport where Premium is recommended, but not required. I've heard the ECU logic is very, very similar across all 1.5T's; but would be worth seeing first hand. :cool:

    upload_2020-1-17_9-27-48.png
     
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  15. TypeSiR

    TypeSiR Senior Member

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    Should’ve tested on a regular 1.5T Civic. Who drag races a CR-V (already maxed out at 190 hp on factory tune using 87)?
     
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