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87 vs 91 (or 92) Octane?

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Comments

  • robr2robr2 Member Posts: 8,805
    Here in MA, ethanol is blended in at 10% as a replacement for MTBE. I believe that is what they did in CA as well. Both are oxygenates but MTBE can damage groundwater supplies with a very low concentration.
  • fezofezo Member Posts: 10,384
    We're another one of those all ethanol states. Can't buy straight gas no matter how hard I try...
    2015 Mazda 6 Grand Touring, 2014 Mazda 3 Sport Hatchback, 1999 Mazda Miata 2004 Toyota Camry LE, 1999.
  • oldbearcatoldbearcat Member Posts: 197
    When I use 87 octane gas on my Pittsburgh runs, the CRV typically gets 24.5 MPG. When I use premium - I use 93 Octane.

    Regards:
    Oldbearcat
  • oldbearcatoldbearcat Member Posts: 197
    One of them is not too far from me - the one in St. Albans. If I'm over that way, I'll stop and tank the car up. Be interesting to see how MPG responds.

    Regards:
    Oldbearcat
  • andysdandysd Member Posts: 87
    Thanks, Oldbearcat - (Do you prefer that to Oldengineer?)

    The following quotes from you beg the question whether they are directly comparable!

    I filled her up with premium outside of Atlantic City, NJ, and got 34.5 MPG running her 70 - 73 MPH on cruise - headed for home in WV.

    When I use 87 octane gas on my Pittsburgh runs, the CRV typically gets 24.5 MPG.

    Regards,
    AndySD
  • oldbearcatoldbearcat Member Posts: 197
    Oldengineer was my original handle - couldn't use it to log in here anymore because Verizon sold out to Frontier here, and, our email and internet changed over. Half the time I forget, have a senior moment, and use the old name. To answer your question - No, they're not comparable. When I was putting gas in the car that time in New Jersey, I noticed that there were no ethanol labels on the pumps. Curious, I went into the station and asked the attendant about it. He indicated that the premium gas didn't have any in it. Given this tank full delivered the best MPG the CRV has gotten to date, I think he was accurate. I've never found 93 w/o ethanol since to try to duplicate these results. All the 87 I find in my multi- state travels is laced with ethanol as well. My apples to apples comparison results in a typical 3 MPG differential between the two. That brings up one of my pet peeves with my CRV. I've made the same round trip to Pittsburgh in a 2006 Jaguar S-Type VDP with a 4.2 Liter V8 under the hood. The Jaguar easily got 30 - 31 MPG running this trip.

    Regards:
    Oldbearcat
  • andysdandysd Member Posts: 87
    Oldengineer, that's great info.

    First, the reason I asked about comparability is it's almost unbelievable that your mpg jumped so much just from a gasoline change, using higher octane than mfr-required (not like your engine required premium and you used regular). Whether or not ethanol is involved, do you believe your CR-V's mpg went up so much - was it 24.5 to 34.5? Just seems over the top.

    Re a different car's mpg for the same trip, in this case, the Jag, I'm not surprised. I think gearing has a lot to do with it. In my '99 Camaro Z28 I've driven three times round trip to The Formula One race in Indianapolis, and gotten just over 30 mpg door-to-door with regular gas. I attribute that to the fact that in sixth gear the engine turns 1,500 rpm at 65 mph, just idling along. Not that I didn't exceed 65. And I went via the Colorado mountains.

    Regards,
    AndySD
  • oldbearcatoldbearcat Member Posts: 197
    Andy:

    I couldn't believe it either. The car's computer kept telling me I was getting this fantastic gas mileage on this trip. Then when I filled it up again in Flatwoods, WV, I checked it with a manual calculation, and, it agreed with the car's computer. A few months ago, my CRV was recalled, and, the dealer reflashed the computer. Today, Wife and I took a run up I 79 to Morgantown and back - about a 350 mile trip. The CRV, running 93 octane for the trip, got 25.1 MPG. That's basically a neglible difference over running 87, and, not worth the extra expense - other than the car feels a bit more athletic.

    Re: The Jaguar - its more than just the gearing (6 speed). The Jag's VVT setup and induction system are more sophisticated than Honda's. Because of this the torque curve for their V8s and V6s is very flat - peak torque is available over a very wide RPM range starting at about 1500 RPM.

    Regards:
    Oldbearcat
  • andysdandysd Member Posts: 87
    Happy Holidays and Merry Christmas to you, Oldbearcat and all who read these golden words:

    Well, talk about dashing cold water! I know you give dependable data, so with your last CR-V trip you have singlehandedly sunk this big ship.

    Regards,
    AndySD
  • steverstever Guest Posts: 52,454
    edited December 2011
    All the more reason to keep a gas log. I'm sure I've transposed plenty of numbers in mine, but the log goes back for years and years so the errors get marginalized. If that one tank of Oldengineeringbearcat's was an anomaly for some reason (maybe a bit of a tailwind in both directions, lol), it'll get "fixed" over time.

    (by the way, this is a paying gig Andy. So no tipping, even if it is the holiday season. :D )
  • andysdandysd Member Posts: 87
    Okay, Steve, if you insist. Let us know when you and your wife come to San Diego, and we'll try Hob Nob, or take you to Phil's BBQ and fix up your cholesterol.

    I have got to get my act together and write C&D. Oldbearcat's last contribution negates the mpg improvement part of the fun, but horsepower increase was actually the starting premise. Also, I'm just about convinced that smoother engine performance is a side benefit.

    In addition to trying higher octane, I plan something else with my Fit. Since I thrash it at the red line in the mountains, I figured out a way to effectively gain about 5 horsepower - and improve cornering: am going to remove the rear seats, which I've read weigh over 100 pounds. That will improve the power to weight ratio by about 2,550 / 2,450 = 1.04, as if the horsepower were increased by 1.04 x 117 = 121.8.
  • steverstever Guest Posts: 52,454
    edited December 2011
    Now you're talking. Forget if the Fit has a spare. Even if it's a compact one, stash it in the closest and replace it with a can of Fix-a-Flat.

    That said, I lost 30 pounds in the last year and my mpg nor performance haven't improved (hasn't helped my car's mpg or hp either :P ).
  • andysdandysd Member Posts: 87
    But you're on the right track, Steve. Lose another 70-plus pounds and then see!
  • oldbearcatoldbearcat Member Posts: 197
    Sorry I sunk your ship. IMO, the software upgrade will no longer let the engine take full advantage of the additional octane. I'm going to run a couple more tankfuls just to make sure. I have run into stations here selling 93 that was actually 87, and, the price differential is not that bad right now. I also did this exercise on a 2008 Saturn Aura (previous business driver) that was equipped with a 3.5 liter pushrod V6 with fairly high compression and VVT. Using 93 octane gas had no effect on its fuel economy.

    Regards:
    Oldbearcat
  • steverstever Guest Posts: 52,454
    edited December 2011
    That gets us back to the question of whether your engine, software flashed or not, is designed to take advantage of the higher octane. Do they still make winter blend fuel? Keep hearing reports that there's little need to change the blend anymore, with all the ethanol in most gas. But that would have hammered your last tank if it was "winter gas".

    But what do I know; another 70 pounds and I'll be a 90 pound weakling. :shades:
  • andysdandysd Member Posts: 87
    With a final grasp at floating flotsam or jetsam, Oldbearcat, can you explain the 34.5 mpg run in the CR-V?

    Regards,
    AndySD
  • oldbearcatoldbearcat Member Posts: 197
    No, I can't - and, I've never been able to duplicate it since. I do take solace in the fact that, with both cars running on 87 octane gas, the CRV manages to get 4.5 more MPG than my stock 1948 Chevrolet Fleetmaster does.

    Regards & Merry Christmas

    Oldbearcat
  • andysdandysd Member Posts: 87
    Jan 9, 2012: I finally emailed the editors of Car and Driver, following:

    Dear Editors:

    In the light of European Car magazine's July 2010 positive result, this is to suggest you repeat your November 2001 test to determine whether using premium gasoline increases horsepower for engines that are not required to use it. The European Car test can be read on http://www.europeancarweb.com/tech/proven/epcp_1007_2010_volkwagen_jetta_proven/- viewall.htmlxx. In their test, using premium gas in a 2010 VW Jetta 2.5 L, dynamometer tests showed an increase of 8 horsepower!

    I started what became a lively forum thread on this subject on Edmunds.com, Gasoline - 87 vs Premium. There seemed to be unanimity that such engines felt peppier but did not conclusively increase miles per gallon. My 2011 Honda Fit Sport 5MT definitely feels stronger with premium, and I wonder whether engines with higher compression ratio, like my Fit at 10.4:1, benefit more. Considering your success with the Fit in the 25 hour Thunderhill race, I hope you might use the Fit in your test.

    As an aside, I love driving my Fit on the San Diego East County two-lane mountain roads, and it flies through the curves, more than holding its own compared to friends' expensive sports cars. I installed 17" Kosei Racing wheels with 215-.45 Kumho SPT tires left over from an '04 Civic, and removed the rear seats reducing weight by 70 pounds.

    Sincerely,
    Andy...
  • steverstever Guest Posts: 52,454
    Heh, since Edmunds competes with Car and Driver for automaker ad dollars and has their own forums, you might get the cold shoulder by mentioning our forums. :shades:

    Maybe they'll edit that part out and get back to you. :D
  • andysdandysd Member Posts: 87
    Good point, Steve, but at least they have the whole story. Let's see if they do anything.
  • andysdandysd Member Posts: 87
    I started this thread after reading an article in European Car that showed a dyno increase in h.p. as the result of using premium gasoline where not required. In summary, I wrote Car & Driver to suggest they conduct another test, quoted in an earlier message.

    All to no avail, and I'm signing off. I don't know the answer definitively, and probably never will . C&D never reacted.

    RIP
  • steverstever Guest Posts: 52,454
    edited June 2012
    A journalist would like to speak to someone who fuels up with 85 octane and has experienced engine issues or a weaker performance at lower elevations because of it. If you use or have used 85 octane, and would like to share your story with a reporter, please send your daytime contact info to pr@edmunds.com no later than Wednesday, June 20 at 2 p.m. Pacific/5 p.m. Eastern.
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