10% ethanol fuel vs ethanol free fuel for boat/outboard motor use?

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Sorry, but there's seriously flawed logic in that statement.

You have NO way to know how long fuel sat in a large storage tank at a fuel farm before it was pumped into the tanker truck which delivered that fuel to the place where you then pumped the fuel into your boat's tank.

You also do not know whether the fuel in question was pumped into the tanker truck from the bottom of that large storage tank, where more water tends to collect. I used to fuel aircraft professionally, and I am speaking from experience, having drained the sumps of fuel trucks more times than I could count. In the case of aviation fuel ethanol was not a factor, but simple condensation from humid air cooling to the condensation point served to cause significant contamination of fuel, such that draining sumps was done every day, and draining of any given sump was continued until the sample of fuel was free of water.

Honda approved the product in question for E10. That, coming from the people who built the product, holds a bit more weight with me than people trying to come up with ideas about what will damage the engine (not having an intimate familiarity with their particular product). This is a pretty modern product, not an antique.

See this link for the manufacturer's recommendation (page 99): https://cdn.powerequipment.honda.com/marine/pdf/manuals/31ZY0600.pdf

The fuel in storage tanks at the "fuel farm" shouldn't yet be oxygenated (have ethanol in it), and it isn't like fuel farms/depots are keeping years of inventory around. And busy stations sell loads of gas (for example, our local Kwik Trip sells a tanker of 87 E10 every day and receives a fresh one every night).

For me, I use E0 91 in our Evinrude outboard, but that goes long periods without being run (and is also a fifty year old engine). If it got run more, I'd run E10 in it and not lose any sleep over it.

As an aside, I really don't like using ethanol. If E10 wasn't subsidized such that it was cheaper than E0, I wouldn't ever use it, but the current pricing structure disincentivizes avoiding it (again, because of the subsidies it receives). I don't think that ethanol is a good product or anything, it's just quite expensive to avoid it (and not always necessary).
 
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As an aside, I really don't like using ethanol. If E10 wasn't subsidized such that it was cheaper than E0, I wouldn't ever use it, but the current pricing structure disincentivizes avoiding it (again, because of the subsidies it receives). I don't think that ethanol is a good product or anything, it's just quite expensive to avoid it (and not always necessary).

Ethanol is used as an octane booster. Previously, MTBE was used. That was found to contaminate groundwater. Prior to MTBE it was TEL (lead).

Part of the reason E0 costs more is that it doesn't contain any octane boosters.

Ethanol subsidies were removed back in 2012 or so, per the news reports a Google search will find for you.
 

Flyingdutchman

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Okay and what if we look at the (probably marginal) power/torque differences?

Theoreticly an normaly aspirated pretty low compression 4 stroke would benefit from a lower octane fuel.

Its not an efi with knock sensors etc... so al settings are fixed. Only things affecting hp are airtemp/pressure and fuel quality.
 
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Okay and what if we look at the (probably marginal) power/torque differences?

Theoreticly an normaly aspirated pretty low compression 4 stroke would benefit from a lower octane fuel.

Its not an efi with knock sensors etc... so al settings are fixed. Only things affecting hp are airtemp/pressure and fuel quality.
Benefit?
 
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Ethanol is used as an octane booster. Previously, MTBE was used. That was found to contaminate groundwater. Prior to MTBE it was TEL (lead).

Part of the reason E0 costs more is that it doesn't contain any octane boosters.

Ethanol subsidies were removed back in 2012 or so, per the news reports a Google search will find for you.
EtOH is used as an oxygenate as is MTBE. It also serves as a volumetric replacement. You're correct that MTBE started out as just an octane booster but at higher concentrations it serves as an oxygenate.

E0 contains aromatics which increase the octane rating above that which would be obtained by isooctane.
 
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Okay and what if we look at the (probably marginal) power/torque differences?

Theoreticly an normaly aspirated pretty low compression 4 stroke would benefit from a lower octane fuel.

Its not an efi with knock sensors etc... so al settings are fixed. Only things affecting hp are airtemp/pressure and fuel quality.

Well, assuming you could get your hands on BOB gasoline, it should have a lower octane rating...
 

Flyingdutchman

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Well the energy density is the same, depending on how the octane rating is obtained. Higher octane fuel in a low-compression engine has no real downside.
Screenshot_20220421-194513_Chrome.jpg

In theory it should have (marginal) more power on octane 95 compared to 98.
However with the 10% ethanol compared to 0% i am not sure how it will work out.

This is more of a theoretical question, in practice it will probably be unoticable.
 
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Correct, as I noted there is no downside but if your engine cannot advance the timing or make some other response to a higher octane fuel then it isn't a help either. I didn't mean to imply it did.
 

FZ1

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Honda approved the product in question for E10. That, coming from the people who built the product, holds a bit more weight with me than people trying to come up with ideas about what will damage the engine (not having an intimate familiarity with their particular product). This is a pretty modern product, not an antique.

See this link for the manufacturer's recommendation (page 99): https://cdn.powerequipment.honda.com/marine/pdf/manuals/31ZY0600.pdf

The fuel in storage tanks at the "fuel farm" shouldn't yet be oxygenated (have ethanol in it), and it isn't like fuel farms/depots are keeping years of inventory around. And busy stations sell loads of gas (for example, our local Kwik Trip sells a tanker of 87 E10 every day and receives a fresh one every night).

For me, I use E0 91 in our Evinrude outboard, but that goes long periods without being run (and is also a fifty year old engine). If it got run more, I'd run E10 in it and not lose any sleep over it.

As an aside, I really don't like using ethanol. If E10 wasn't subsidized such that it was cheaper than E0, I wouldn't ever use it, but the current pricing structure disincentivizes avoiding it (again, because of the subsidies it receives). I don't think that ethanol is a good product or anything, it's just quite expensive to avoid it (and not always necessary).
Right. Hard to get E0 down here. Been running E10 in my Evinrude 2 stroke outboard for 20 years. No problems. I'd prefer the E0 if it were available but it ain't.
 
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In previous years i always ran what we in europe call E0 fuel which is octane 98 gasoline with 0% ethanol, this because i know that this is easier on the fuel lines/gaskets and does not attract moist or leave behind residue as much as E10 which is the regular octane 95 with the legal requirement of 10% ethanol for emissions(scam).

However with the recent rise in fuel prices and even normal E10 fuel rising above 2 euros a litre i decided to now switch to the cheaper E10, this because it was more like peace of mind to run the simple carburated 2008 Honda hp 20 4 stroke outboard 380cc 2 cylinder on the fuel more or less designed for modern turbo cars with the higher octane rating, in theory this motor as a normaly aspirated motor should benefit from a lower octane fuel.

My only concerns are:
- Because ethanol is hydroscopic the fuel absorbs moisture from the air, all modern cars have vacuum sealed fuel system/tank so that is not a problem. However my boat just has a oem plastic 25l tank with a vent screw on the cap. The tank is in outside air/rain etc.. and is not covered. i can not close the valve because i tried this before but if the sun kicks in it almost explodes because of the pressure build up:ROFLMAO:

- My honda owners manual says that the system is designed to run max 10% ethanol fuel, i use the boat a lot and eventhough it doesnt consume a lot its more or less empty every month so i dont see the deteriorating of the ethanol as hazard like it is with a lot of classic vehicles.

-Outboard motors run at lower water/oil temps and eventhough my engine sees a lot of hours at full throttle 25 knts the nr1 problem with (carburated) outboards is fuel diluition at (cold)trawling speeds which is invitable. Last year my oil also came out pitch black like it came out of a 15k oci diesel engine oil change and smelt like gasoline.
Will the ethanol/fuel in the oil be a reason for problems because the motor spends its life in such a humid enviroment? I mean problems that can be created by the ethanol.

Let me know if you have any experience on this topic and if theres something i am missing out on.

-Powerwise do you think there will be any (marginal) difference? This is not a 2.5 bar boost world rally car but a carburated 380cc 2 cyl 4 stroke with 20hp. Generaly speaking the lower the octane the more power it would have. It has no knock sensors so everything is fixed.
How does it feel to pay $10 per gallon? I ask so I can prepare for it 6 months from now.

As for the 10% stuff, it's fine to use, just run/dump it out before you store the machine.
 
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All I can tell you is 90% of my business is cleaning and repairing boat injectors for marinas, E10 is responsible for a lot of injector and composite fuel tank damage, I see it every day.
Unlike car engines boats live on water, the fuel gets saturated with absorbed moisture and at some point it will drop out. The moisture gets into the injectors and corrodes them. I am doing a set today that have rust inside the injector from a metal fuel rail
Trav knows whats going on, add Fuel Stabilizer, Heat or something similar, my boat was 2 Cycle and not fuel injected
 
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My 2017 Yamaha 4 stroke 200 HP outboard manual states that recommended octane is 89 with no more than 10% ethanol. I still treat it with Stabil.
 
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Flyingdutchman

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A different theory, ethanol creates less power. If e10 has 10% ethanol simply speaking would have 10% less power than e0. I know its not that simple but just an example.

A carb size is a fixed jetting, it will never readjust according to lambda values etc...
If e10 has 10% less energy then on e10 my outboard would have 10% less power.
Does this hold any truth in any form? I know that fuel consumption on most efi vehicles goes up (slightly) if you switch to e10 from e0.

Today i did my first high speed run on the e10 thats still in the tank and i know it does not hold any facts but it felt less powerfull/like it would not rev as high as on e0.
 
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A different theory, ethanol creates less power. If e10 has 10% ethanol simply speaking would have 10% less power than e0. I know its not that simple but just an example.

A carb size is a fixed jetting, it will never readjust according to lambda values etc...
If e10 has 10% less energy then on e10 my outboard would have 10% less power.
Does this hold any truth in any form? I know that fuel consumption on most efi vehicles goes up (slightly) if you switch to e10 from e0.

Today i did my first high speed run on the e10 thats still in the tank and i know it does not hold any facts but it felt less powerfull/like it would not rev as high as on e0.
Regular gasoline contains ~116,090 to 124,340 BTU/gallon. Reformulated gasoline contains 113,602 to 121,848 BTU/gallon, so about 3% less BTU per gallon.

Without changing anything else, you’ll be down roughly 3% on power. It takes a certain amount of energy to do a certain amount of work, if you give the system slightly energy, you’ll get less work.
 
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I did not know about this and ran cheap ethanol gas in our boat the last two years. Now it's sitting with some type of fuel problem. And I used Marine Stabil as well.

Don't know if it was the fuel but it will be E0 from here on out.
 
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