markchilcutt Posted April 25, 2016 Share Posted April 25, 2016 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 Link to comment Share on other sites More sharing options...
Baller_ MISkier Posted April 25, 2016 Baller_ Share Posted April 25, 2016 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. Link to comment Share on other sites More sharing options...
Baller_ MISkier Posted April 25, 2016 Baller_ Share Posted April 25, 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. Link to comment Share on other sites More sharing options...
markchilcutt Posted April 25, 2016 Author Share Posted April 25, 2016 @MISkier the manual says 85 minimum 93 max and recommends using 93. The manual never mentions non ethanol or ethanol gas. Link to comment Share on other sites More sharing options...
Baller_ MISkier Posted April 25, 2016 Baller_ Share Posted April 25, 2016 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. Link to comment Share on other sites More sharing options...
Baller Skoot1123 Posted April 25, 2016 Baller Share Posted April 25, 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. Link to comment Share on other sites More sharing options...
Baller eleeski Posted April 25, 2016 Baller Share Posted April 25, 2016 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 Link to comment Share on other sites More sharing options...
stroke Posted April 25, 2016 Share Posted April 25, 2016 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. Link to comment Share on other sites More sharing options...
Baller_ DW Posted April 25, 2016 Baller_ Share Posted April 25, 2016 @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). Link to comment Share on other sites More sharing options...
markchilcutt Posted April 25, 2016 Author Share Posted April 25, 2016 @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. Link to comment Share on other sites More sharing options...
Baller Jordan Posted April 25, 2016 Baller Share Posted April 25, 2016 Octane is anti-knock index....not a measure of potential power...If you are seeing a big difference in performance on higher octane it is likely because your engine management system is changing the timing on your engine to avoid knock. Link to comment Share on other sites More sharing options...
stroke Posted April 25, 2016 Share Posted April 25, 2016 Thanks for the octane lesson........just trying to keep it simple Link to comment Share on other sites More sharing options...
Baller escmanaze Posted April 25, 2016 Baller Share Posted April 25, 2016 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. Link to comment Share on other sites More sharing options...
stroke Posted April 25, 2016 Share Posted April 25, 2016 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. Link to comment Share on other sites More sharing options...
markchilcutt Posted April 25, 2016 Author Share Posted April 25, 2016 @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. Link to comment Share on other sites More sharing options...
Baller LeonL Posted April 25, 2016 Baller Share Posted April 25, 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. Link to comment Share on other sites More sharing options...
Baller Waternut Posted April 26, 2016 Baller Share Posted April 26, 2016 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! Link to comment Share on other sites More sharing options...
sixball Posted April 26, 2016 Share Posted April 26, 2016 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! Link to comment Share on other sites More sharing options...
Baller oldjeep Posted April 26, 2016 Baller Share Posted April 26, 2016 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. Link to comment Share on other sites More sharing options...
Baller LeonL Posted April 26, 2016 Baller Share Posted April 26, 2016 Given the same price (as you mentioned) I would go with the non ethanol. Link to comment Share on other sites More sharing options...
markchilcutt Posted April 26, 2016 Author Share Posted April 26, 2016 Thanks for all the input everyone. I am going to run the 88 NE for awhile and see how it does. Thnx MC Link to comment Share on other sites More sharing options...
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