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88 non ethanol VS 91 ethanol

markchilcuttmarkchilcutt Posts: 884 Crazy Baller
So I have the option to run 88 non ethanol or 91 ethanol gas in the 2014 6.2 prostar at high elevation. The cost is the same per gallon which would you use and why? I am leaning toward the 88 NE.
Thanks, MC
Ski it if you can!!!!

Comments

  • MISkierMISkier Posts: 2,253 Mega Baller
    I would do the 88 without the ethanol, but I am not at high elevation. What octane does the manual require?
    The worst slalom equipment I own is between my ears.
  • MISkierMISkier Posts: 2,253 Mega Baller
    edited April 2016
    As for why I would use the 88, Ethanol does not have the same energy return as pure gasoline. You get worse mileage with Ethanol blends. Also, there are issues with fuel system components and Ethanol, though not as prevalent in modern engines and vehicles.
    The worst slalom equipment I own is between my ears.
  • markchilcuttmarkchilcutt Posts: 884 Crazy Baller
    @MISkier the manual says 85 minimum 93 max and recommends using 93. The manual never mentions non ethanol or ethanol gas.
    Ski it if you can!!!!
  • MISkierMISkier Posts: 2,253 Mega Baller
    It sounds like the 88 would be fine. I wonder why there is no mention of Ethanol. It seems I've seen other manuals at least caution against exceeding 10% Ethanol. Try a couple tanks of the 88 and see how it runs/accelerates.
    The worst slalom equipment I own is between my ears.
  • Skoot1123Skoot1123 Posts: 1,776 Mega Baller
    edited April 2016
    Interesting question and am looking forward to hearing others input as well. When we bought our boat new (2007) we asked about the octane rating and why the manufacturer recommended a higher octane. The response was a little funny - they said that a high percentage of boat owners don't use their boats during the week and as a result the boats only get used on the weekend. With the boat sitting and not being used, the fuel in the tank would degrade (as an example: fuel going from a 93 octane down to an 88 octane rating). This assumes no fresh fuel was put in the tank before the next weekend. You be the judge of that one!

    Another thing is that the octane rating depends on elevation. A lower octane rating at a higher elevation acts the same as normal octane at sea level. IE: 85 octane in Idaho/Utah/Colorado is "the same as" 87 octane in Illinois/Indiana/Florida (example only)

    So, my opinion @markchilcutt is that you should go with the 88 NE straight gas.
  • eleeskieleeski Posts: 3,622 MM Trick Skier / Eccentric Person
    My Cessna 182 which was approved for cargas ran better on 87 regular than 100 octane avgas. Better power and lower fuel burn.

    At altitude, the need for high octane fuel is reduced along with the air pressure. Lower octane fuels typically have more energy so you should get better performance out of the lower octane fuel at altitude. Modern fuel injection and computers make this less important. Alcohol is significantly less energy dense so your fuel economy will be worse with any alcohol blend.

    Alcohol has incompatability issues with older engines. Plus the alcohol can dissolve out old varnish and sludge from the tank. Also alcohol has different properties regarding water contamination and can cause (or cure) water in the fuel problems. A 2014 boat should be fine with an alcohol blend - alcohol blends are a standard fuel now.

    Use whatever is easiest for you and stress about your skiing instead.

    Eric
    Skoot1123
  • strokestroke Posts: 5 Baller
    Check with your area Mastercraft Dealer, but I've recently been told by mine that it's no more than 10% ethanol. Here at Calgary we run 6.2 with 91 octane, at our elevation the power diff between high octane and reg fuel is big. I believe we (predator bay waterski club) we have sourced 91 octane with no ethanol blend.
  • DWDW Posts: 1,850 Mega Baller
    @Skoot1123: The reason given is because as fuel sits with exposure to the atmosphere there is a certain amount of evaporation happening which over time lowers the octane of the fuel. As noted, the marinizers have to compensate for this by suggesting a higher octane fuel than ideally required if the fuel remained fresh.

    As an example, the engine in my boat has a compression ratio (what primarily drives octane requirements along with ignition timing) of 10:1 compared to the typical 9.4:1 in almost all tournament ski boats. My boat runs fine on regular 89 octane (fresh) fuel @ 950' elevation even with slightly advanced timing.

    You will also note that fuel sold at higher elevations is lower octane for each of the three common grades supporting Erics comments on altitude effects (which basically lowers compression ratio at higher elevations).
  • markchilcuttmarkchilcutt Posts: 884 Crazy Baller
    @stroke thanks for the info. I also have access to 91 non ethanol but it is currently $4.99 per gallon. The 88 NE is about $2.50 per gallon as is the 91 ethanol. If money wasn't an issue I would run the 91 NE all the time.
    How does your boat due on making or gaining oil? I have heard the 6.2 will gain oil level due to un burnt gas getting past the rings? I am still on my first oil change and haven't noticed oil gaining.
    Ski it if you can!!!!
  • strokestroke Posts: 5 Baller
    Thanks for the octane lesson........just trying to keep it simple
  • escmanazeescmanaze Posts: 572 ★★★Triple Panda Award Recipient ★★★
    Especially if your manual says you can go as low as 85, and that's at sea level, then I would most certainly prioritize ridding yourself of ethanol and all the terrible things it can bring, especially when sitting for a long time over a cold utah winter.
  • strokestroke Posts: 5 Baller
    Yes I've seen the oil levels come up, have seen a 1L gain on 50 HR service interval. Lots of schools of thought on why this happens, I think I'll wait and read comments on the subject before I say anything.
  • markchilcuttmarkchilcutt Posts: 884 Crazy Baller
    @stroke @Jody_Seal I think summed it up well. An engine that is built/speced to run at 210 degrees Fahrenheit running at 170 due to the marine application is not generating enough heat to fully seat the piston rings allowing fuel to blow by.
    Ski it if you can!!!!
  • LeonLLeonL Posts: 2,255 Crazy Baller
    edited April 2016
    VP Racing fuels says that their 112- 116 octane will not degrade with as much as two years of storage. We use 112 in a drag race VW with 12:1 compression ratio. Themguy who delivers gas to our lake says gas in our tank for up to a year should not be a problem.
    Leon Leonard Stillwater Lake KY - SR Driver SR Judge
  • WaternutWaternut Posts: 1,511 Crazy Baller
    Ethanol is not the fuel of satan despite what most gearheads will lead you to believe. Rather than rant for or against ethanol since I realize no one will change their opinion anyway, I'll leave you with this. If you don't like to use your boat, I would definitely recommend using non-ethanol gas. If you actually use your boat more than a few times a year....use what ever gives you a warm fuzzy feeling inside!
    sixballSkoot1123Jody_SealJordan
  • sixballsixball Posts: 210 Baller
    Yeper If you running gas through the boat in less the 30 or 40 days you are not going to see a drop in octane. Not enough to change the performance. Running more octane then needed gets you nothing other then less beer money in your pocket.
    Brake in today is not going to change the rings performance. Rings if you are getting good oiling will not touch the cylinder walls. They ride on a very thin coating of oil. Oil is pulled off the cylinder wall with a pressure difference. Some call the oil ring a scraper, Not so! If your ring were to ride on the cylinder wall they would ware so fast we woud be replacing them weekly!
  • oldjeepoldjeep Posts: 3,116 Mega Baller
    Use the 91 if you want full power, if it makes enough for you on 88 then use that. Somehow my boat fired right up (again) after sitting with a tank of e10 for 6 months. E10 works fine in everything I own, no snake oil ever added.
    Chuck P
    Not a mechanic but I play one at home
    BrennanKMN
  • LeonLLeonL Posts: 2,255 Crazy Baller
    Given the same price (as you mentioned) I would go with the non ethanol.
    Leon Leonard Stillwater Lake KY - SR Driver SR Judge
  • markchilcuttmarkchilcutt Posts: 884 Crazy Baller
    Thanks for all the input everyone. I am going to run the 88 NE for awhile and see how it does.
    Thnx MC
    Ski it if you can!!!!
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