Gasoline powered boats and fuel consumption

ttmott

ttmott

PhD in OCD
GOLD Sponsor
TECHNICAL Contributor
Apr 3, 2012
8,162
Space Coast Florida
Boat Info
2006 52 Sedan Bridge
Engines
Cummins QSM11
This may be obvious to many -
Over the years there has been many comments on the fuel consumption. What is not usually provided is if the fuel has ethanol as a component. The ethanol content can drastically affect fuel consumption depending upon the percentage of ethanol.

Gasoline to burn efficiently in an engine needs a typical sociometry of 14:1 (Air to Fuel ratio)
Ethanol to efficiently burn in an engine is around 9:1.

Any mix of Ethanol and Gasoline will result in a ratio loss of work and efficiency.

So, a typical pump gasoline that has 10% ethanol will see that 10 percent burning at about 60% efficient that of gasoline netting in a reduced MPG or GPH capability.

With a little math done, is the added cost of non-ethanol fuel worth the gain in efficiency?
 
Personally non-ethanol fuel is worth the cost, but not based on efficiency alone but based on what it does to the fuel components like non ethanol rubber hoses on carbureted engines. Even my 2020 Yamaha had ethanol issues at first until I switched it over to LL100, aviation fuel.
 
In FL and MD do you guys have the choice between regular unleaded and non-ethanol unleaded at marinas? Up here in MI I've never seen anything other than ethanol-free gas sold on the water.
 
I think a bigger component of the equation is the fact that ethanol also has about 30% less energy density by volume. You gotta burn more of it to go the same distance/speed. I would imagine the efficiency is a second or third order effect but certainly both will result in a higher burn rate.

But ethanol in gas isn’t about efficiency.
 
Stee6043 said:
In FL and MD do you guys have the choice between regular unleaded and non-ethanol unleaded at marinas? Up here in MI I've never seen anything other than ethanol-free gas sold on the water.
Click to expand...

Same here on the water, I believe, I am diesel, so I don't pay much attention to prices/content on the water. I think the laws for having ethanol fuel is only for land vehicles. At least for today.
 
Screw the science.

Ethanol is all about the politics.

It's not a question for debate, its a fact !

BEST !

RWS
 
Maybe A Dancer said:
Screw the science.

Ethanol is all about the politics.

It's not a question for debate, its a fact !

BEST !

RWS
Click to expand...

Well NASCAR uses it on purpose. They use Sunoco Green E15, a 98 octane, unleaded fuel blend. When used in an engine that is designed for it, it's great. Otherwise it wreaks havoc on internal parts.

I do think it has no place in the general public fuels, unless it is only used in new cars designed for it's use.
 
Maybe A Dancer said:
Screw the science.

Ethanol is all about the politics.

It's not a question for debate, its a fact !

BEST !

RWS
Click to expand...

Really? I thought ethanol was initially added to fuel to increase the octane rating in the same way lead used to...but we decided lead was bad...which is generally not considered a conspiracy theory...

I'm not a chemist but I believe octane rating is important, it's not 100% about how much energy by volume the fuel has...because...I think....engine knocking will damage engines.

E85 may be political but using ethanol in fuels to manage octane levels and engine performance is not exactly tin foil hat territory?
 
E85 was cheaper then E10...I did a comparison in a suburban fuel miledge and cost per mile....E85 cost alot more per mile despite the savings per gallon
 
Jus Cruisin said:
But e85 is the macdaddy for making horsepower in performance applications. Generally you are talking 10-15% additional horsepower over non ethanol gas. Now, e10, yes not as good.
Click to expand...
E85 is cheap horsepower from a couple of aspects - it's cooling effect allowing a greater charge, it's oxygen content, and it's octane rating. But higher compression or forced induction is needed to make best use.
 
Skybolt said:
Personally non-ethanol fuel is worth the cost, but not based on efficiency alone but based on what it does to the fuel components like non ethanol rubber hoses on carbureted engines. Even my 2020 Yamaha had ethanol issues at first until I switched it over to LL100, aviation fuel.
Click to expand...
Old news on the rubber goods - just about everything is compatible these days. The downside these days is ethanol is hydroscopic (it absorbs water) and can result in corrosion and gumming. They put additives in gasoline to help avoid.
 
Stee6043 said:
In FL and MD do you guys have the choice between regular unleaded and non-ethanol unleaded at marinas? Up here in MI I've never seen anything other than ethanol-free gas sold on the water.
Click to expand...
How many boats on trailers do you see at the local Racetrack filling up?
 
This thread is so timely. I just completed a state of Michigan survey on whether or not we should change from a gas tax to a usage tax (miles driven). Cheap gas here we come! :)
 
Stee6043 said:
Really? I thought ethanol was initially added to fuel to increase the octane rating in the same way lead used to...but we decided lead was bad...which is generally not considered a conspiracy theory...

I'm not a chemist but I believe octane rating is important, it's not 100% about how much energy by volume the fuel has...because...I think....engine knocking will damage engines.

E85 may be political but using ethanol in fuels to manage octane levels and engine performance is not exactly tin foil hat territory?
Click to expand...
Ethanol is an additive into gasoline, a blend stock actually, that brings an oxygen molecule to meet EPA Clean Air Standards back in the 80's/90's. The original, preferred oxygenated compound was Methy tertiary-butyl ether, or MTBE. However, initially, it was not available in large quantites and it was expensive. One side benefit of MTBE is that you got an octane boost from it. So, our politicians, in their infinite wisdom, decided that taking corn out of the food supply and putting it into the energy stream would be the answer.

The original desire to reduce tail pipe emissions was/is noble. The oxygen molecule added to gasoline had the desired affect of reducing Carbon Monoxide emissions, especially in cool/cold weather. The part they didn't count on was the increase in formaldehyde levels in the atmosphere.

The road......good intentions.

Jaybeaux
 
Stee6043 said:
This thread is so timely. I just completed a state of Michigan survey on whether or not we should change from a gas tax to a usage tax (miles driven). Cheap gas here we come! :)
Click to expand...
That's so they can capture all the Teslas and other EVs clogging the highways!
 
Jaybeaux said:
Ethanol is an additive into gasoline, a blend stock actually, that brings an oxygen molecule to meet EPA Clean Air Standards back in the 80's/90's. The original, preferred oxygenated compound was Methy tertiary-butyl ether, or MTBE. However, initially, it was not available in large quantites and it was expensive. One side benefit of MTBE is that you got an octane boost from it. So, our politicians, in their infinite wisdom, decided that taking corn out of the food supply and putting it into the energy stream would be the answer.

The original desire to reduce tail pipe emissions was/is noble. The oxygen molecule added to gasoline had the desired affect of reducing Carbon Monoxide emissions, especially in cool/cold weather. The part they didn't count on was the increase in formaldehyde levels in the atmosphere.

The road......good intentions.

Jaybeaux
Click to expand...
I just knew you would be fun at parties
 
You must log in or register to reply here.

Forum statistics

Threads
113,219
Messages
1,428,829
Members
61,115
Latest member
Gardnersf
Back
Top