Howdy, Stranger!

It looks like you're new here. If you want to get involved, click one of these buttons!





87 vs 91 (or 92) Octane?

2

Comments

  • robr2robr2 BostonPosts: 7,769
    Been there - was kind of bored with the weather. I like real seasons with snow and leaves and rain and cold and hot and humid.
  • berriberri Posts: 4,159
    Three of us have seen indication of about 10% improvement in fuel mileage

    Are you sure its the octane level? I think a lot of premium fuel doesn't contain ethanol.
  • andysdandysd Posts: 87
    Good point, but in CA ethanol is unavoidable. See a quote:

    ETHANOL CONTENT IN CALIFORNIA'S GASOLINE INCREASES TO E10
    POSTED: MAR 05, 2010

    Since the ban of MTBE in California, the state has used a 5.7% blend of ethanol instead of the E10 more common across the rest of the country. But today California is switching over to the 10% blend. This is good news for consumers who can now use a higher content of renewable fuel and for America's ethanol producers who have a newly expanded market - but questions remain about the future of ethanol use in California as the state's low carbon fuel standard moves toward implementation. As written, corn-based ethanol may not qualify as a low-carbon fuel because the state insists on charging it with additional penalties for "indirect effects," as opposed to only the "direct effects" charged to other fuels.
  • andysdandysd Posts: 87
    I hear you, but after about 17 years in and around NYC/Roslyn/Tarrytown, 3 years in the Navy, 5 years near the beach in Lomita CA, 11 years in Holland (still have the same ex-Dutch wife), 20 years in Saudi Arabia, a couple of years in Houston, a year in Calgary, we chose Socal in sight of the Pacific for retirement 27 years ago.

    You probably wouldn't believe all the things we can do, e.g., within 20 minutes of twisty two-lane mountain and desert roads, that I enjoy every weekend on two and four wheels with fellow enthusiasts. We go over Mt Laguna's 6,000 feet almost every week where there is plenty of climate change, colored leaves, sign "Against the law to throw snowballs at vehicles."
  • Whether I fill the CRV up with premium fuel or not depends on the price spread between the fuels. For a good while here, the price differential was too much to make it worthwhile.

    In town, the car seems peppier as I noted, low end torque feels slightly better, and the hesitation is gone.

    Regards:
    Oldbearcat
  • The best verification I have is that I make a 500 mile roundtrip to Pittsburgh once a month for business. I've used both fuels for a bunch of trips, and, the CRV consistently does better on premium gas. The best the car's ever done - 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. I suspect the gas I bought didn't have any ethanol in it, and, it's not available in my state. My CRV is a 2wd by the way.

    Regards:
    Oldbearcat
  • steverstever YooperlandPosts: 40,228
    edited December 2011
    There are ~8 "pure gas" stations in WV (assuming the list is current). Not a lot.

    Moderator
    Need help navigating? stever@edmunds.com - or send a private message by clicking on my name.

  • andysdandysd Posts: 87
    That's good data. For comparison, can you say what your mpg is for the same trip using 87 gas? What octane was the premium you used? The (current) CR-V engine has a compression ratio of 10.5, pretty high, possibly leading to the conclusion that higher c.r. engines (specifying 87 octane) benefit relatively more from octane higher than 87.

    I got the email address to send an email to the editors of C&D, and started a draft.

    Regards,
    AndySD
  • steverstever YooperlandPosts: 40,228
    "But what if you don't have a high performance vehicle? Will putting high octane premium gas in your car make it run any better? Well, mechanics say it could actually make your car run worse.

    "They have sensors on what the combustibility rate is in the pistons and stuff, and it will screw up the sensors because the rate is slower than what regular gas fires at higher combustibility rates," said Fox Negaunee sales associate, Casey Massie."

    Premium vs. regular gas, what's the difference? (FoxUP)

    The comments there run the same gamut as here. :D

    Moderator
    Need help navigating? stever@edmunds.com - or send a private message by clicking on my name.

  • andysdandysd Posts: 87
    edited December 2011
    It's great that our Host, Steve, is contributing his ideas and info from links. Thank you, Steve. By the way, we need your help again if you can make that original link available. The way I pasted it in Msg #1 now goes to a subscription page for European Car! It worked for a while.

    As to the question, "But what if you don't have a high performance vehicle? Will putting high octane premium gas in your car make it run any better?"

    As a preliminary answer, none of the vehicles belonging to contributors to this thread are high performance vehicles, and they are reporting benefits. The car in the test that started this off, in Msg #1, is a VW Passat with the base Golf engine, the 2.5 5-cylinder. Mine is a Honda Fit. Oldengineer's is a Honda CR-V. Another is a "VW."

    I'm not trying to push my personal idea, but instead am trying to go further with the test that reported benefit in the link referenced in Msg #1, and so far we are seeing real life evidence that there is benefit.
  • steverstever YooperlandPosts: 40,228
    edited December 2011
    Hm, the link is still working okay for me.

    Here's a text only cached version that may stick around for a while.

    Car and Driver has looked at this before btw. Back in '01 they said "only a few vehicles calibrated for regular fuel can advance timing beyond their nominal ideal setting when burning premium." Performance gains were minimal (or negative in the case of an Accord in their fleet). Regular or Premium?

    If you're still composing your note to C&D, you can ask them if their story still holds true with your higher combustion Fit engine.

    Moderator
    Need help navigating? stever@edmunds.com - or send a private message by clicking on my name.

  • andysdandysd Posts: 87
    edited December 2011
    Thank you, thank you, Steve. You must work 24 hours a day!

    Yes, I'll reference the '01 C&D test, but we're getting current real life evidence from your forum contributors that it does help, just like the recent subject test concluded.

    Regarding the V-6 Honda in the '01 C&D test, "The Accord took a tiny step backward in power (minus 2.6 percent) and performance (minus 1.5 percent) on premium fuel, a phenomenon for which none of the experts we consulted could offer an explanation except to posit that the results may fall within normal test-to-test variability."

    I like the text version although it doesn't have the graphs.

    From the recent European Car magazine test, the h.p. gain on the lowly base 2.5 liter 5-cylinder VW engine increased from 138 to 145! That's 5 per cent. And:

    Conclusion
    Does higher octane fuel make a difference on all vehicles? It did in this case. Because of VW's advanced electronics and highly adaptive engine management, the Jetta 2.5L has an elastic response to a changes in octane levels. Once we put in the 87 octane, we could feel the drop in performance - less responsive, less peppy, and overall just different. The engine instantly detected the reduced octane levels and adapted for standard performance. This analysis was based on more than 1,200 miles of driving over a week.
    Switching between the two octanes allowed us to use the dyno to detect and confirm or refute any driving subtleties we noticed during the week. Even though the Jetta's gas tank flap advises 87 octane, the dyno graphs clearly show that running premium gasoline does have performance benefits including, a slight increase in fuel economy. In the end, you get what you pay for. If you want standard performance use standard gasoline. But if you want premium performance, pay for premium gas.
  • steverstever YooperlandPosts: 40,228
    edited December 2011
    "we could feel".

    That's a red flag for me and it really indicative of the placebo effect. I put premium gas in my car, so it must be running better. Back in the day, when I got a new pair of sneakers, I could run so fast I'd challenge my older brother to a foot race. Never beat him. :D

    Testers should stick to repeatable results, not seat of the pants stuff.

    Road and Track says "There's no benefit in octane higher than the recommended one (as systems generally adjust downward in response to knock, not upward until they hear it)."

    Moderator
    Need help navigating? stever@edmunds.com - or send a private message by clicking on my name.

  • andysdandysd Posts: 87
    Since you've read the European Car test, I'm surprised you don't give it any credence. A five per cent increase in horsepower is not about seat of the pants.
  • steverstever YooperlandPosts: 40,228
    edited December 2011
    And what's the margin of error on that number? Should we add (or substract) one percent? Three?

    Fun stuff, got any more links anyone?

    Moderator
    Need help navigating? stever@edmunds.com - or send a private message by clicking on my name.

  • andysdandysd Posts: 87
    Steve, as to more links, I just googled extensively, and find unanimity in the position that using premium where not required by the manufacturer is a waste of money.

    However, I am going to continue my personal test with my 2011 Honda Fit, to calculate mpg using 91 for comparison, and to write C&D to see if they'll do a test to confirm or refute the recent European Car mag test. I'll also refer to C&D's own 2001 test.

    If I were a car commuter where fuel cost were an economic consideration, I wouldn't think for a moment of using premium (unless unexpected reports come from this forum of more economy with premium).

    I do hope others will run comparative mpg tests, and advise this forum.

    Just a personal decision, but I'm also going to continue to evaluate the seat of the pants indication that my Fit is more powerful. I drive this car in such a way that paying a little more for gas would be worth it to me. On many weekends, with other real sports cars, we push the mountain road curves. With no desire to collect speeding tickets, we do not drive at high speed on the straights.

    I believe the contributors who say their cars run smoother on premium, that it applies to certain engines. The literature indicates that high mileage cars do run smoother on premium due to build-up of carbon on the pistons and cylinders, effectively raising the compression ratio.

    Our 2011 Accord SE is so smooth, though, and I wouldn't use more horsepower if I had it, so I don't see any reason to even try 91 in it.

    I also have a '99 Camaro Z28 I special-ordered new 13 years ago, in which I've used regular gas almost all its life. It runs fine on regular, which is permitted by the owner's manual, and I don't have any need or desire for the full 305 h.p.
  • steverstever YooperlandPosts: 40,228
    edited December 2011
    where fuel cost were an economic consideration

    Well, some people run a higher octane just for that reason - they report getting better mileage. But the price differential has to be just right; usually that's a dime but it varies a lot.

    For the same reason, some people run the ethanol free stuff if they can find it, because their gas logs show the extra cost of the gas is made up by the higher mpg.

    I had a Fit Sport for a weekend and it seemed peppy enough. On my test drive of the Fit automatic, it was such a dog with three people in it that I'd want to switch to premium, Techron, Heet, aviation gas, vodka - anything to get it where it could merge on the freeway. :shades:

    Moderator
    Need help navigating? stever@edmunds.com - or send a private message by clicking on my name.

  • andysdandysd Posts: 87
    Around San Diego, there's about a 6% markup for premium, so you'd have to beat that with improved gas mileage. Non-ethanol not available in California.

    The second gen Fit like mine has a little more h.p. at 117, and with the manual transmission feels pretty strong. You can't be afraid to wind it up to 7,000 max rpm where it is still very smooth. Really a fun car. I have 17" wheels and 215/45 Kumho SPT sport tires. I didn't buy the wheels/tires for the Fit, but had them in the garage for 7 years from a weak moment of buying for an '04 Civic I had at the time.
  • steverstever YooperlandPosts: 40,228
    edited December 2011
    Hey, there's a whopping 5 "pure gas" stations in California. :)

    Maybe we'll get back out that way some day and we can meet for coffee at the Hob Nob Hill and compare gas logs (my wife is from La Mesa but all her relatives moved, durn it)

    Moderator
    Need help navigating? stever@edmunds.com - or send a private message by clicking on my name.

  • andysdandysd Posts: 87
    Steve, are Hosts employees or volunteers?

    You're right about those five ethanol-free gas stations in CA. I reported them a few days ago, and forgot about them, because I've read ethanol is in all gas in CA, which is what the reference says that I pasted below.

    Ethanol in gasoline seems to be a complicated and controversial issue, dangerous for boats with fiberglass tanks - but boaters with gasoline engines have no choice except to replace their fuel tanks with stainless steel. Here's a reference:

    Ethanol Free Premium Unleaded Gasoline Coalition

    California Is Not A Mandatory Ethanol State
    But It Might As Well Be

    California does not have a mandatory ethanol blending law, but it should because ethanol is already in all of the gasoline in the state. The California Air Resources Board has an agreement with the EPA to blend ethanol into all of the gasoline in California at the 5.7% level. That level has been changed by a California law that allows the distributors to go to E10 by 2010 and they surely will for the economic benefit to them. It is unfortunate that the greedy ethanol companies and the oil companies pay no attention to the known problems with ethanol in gasoline. There are no exemptions in the California agreement and no requirement for labeling pumps, so you get problems like this.
    Prohibit Ethanol Blending In All Premium Unleaded Gasoline

    Every mandatory E10 state has exemptions to their blending law, because there are a number of piston engine applications that should not, and some that cannot, use ethanol blended gasoline. Unfortunately the exemptions are not uniform. They vary from only one exemption in Washington, aircraft, to a universal exemption of premium unleaded in Missouri. All states exempt aircraft usage, but most states like Oregon and Washington make it almost impossible to get unblended gasoline. Oregon is the only state that allows for unblended regular and premium gasoline for the exemptions, and then makes it almost impossible to get any unblended gasoline. All other mandatory ethanol states just allow clear premium unleaded gasoline for the exempted classes.

    The following piston engine applications should not use ethanol blended gasoline:

    Any 2 cycle engine used in tools, watercraft, snowmobiles, etc., or small 4 cycle engines.
    Any engines used in an emergency stationary engine application like a generator or a pump, especially in a humid climate.
    All watercraft. Ethanol blended gasoline should never be used in a marine environment.
    Antique and classic cars and classic motorcycles.
    All aircraft.

    All of these users must be able to get ethanol free (E0) gasoline. If you live in a state without a mandatory ethanol blending law, you have no exemptions, ethanol will eventually be blended into all of your unleaded gasoline and there is no requirement in EISA 2007 to label gas pumps with ethanol content.
  • robr2robr2 BostonPosts: 7,769
    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 Posts: 9,329
    We're another one of those all ethanol states. Can't buy straight gas no matter how hard I try...
  • 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
  • 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 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
  • 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 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
  • 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 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 YooperlandPosts: 40,228
    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 )

    Moderator
    Need help navigating? stever@edmunds.com - or send a private message by clicking on my name.

2
Sign In or Register to comment.