Mid-range Engines and Ethanol Fuel Considerations

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Author Topic:   Mid-range Engines and Ethanol Fuel Considerations

stubbleduck posted 06-16-2006 10:32 AM ET (US)
Several of you may have tossed this around already and hopefully someone will get me up to speed or pose some thought or research ideas. I have narrowed my engine choices down to a Yamaha two-stroke 70-HP, Merc 75-HP Classic, or a Merc EFI 60-HP four-stroke. Much of this has to do with the [ratio of] weight to horsepower for my lighter weight 16-foot aluminum fishing boat.
Now fuel economy is important, and typically I have always stayed clear of ethanol. I would like to start burning ethanol in my boat as I am from [New England] farmland, and most of us feel we need to make the conversion. From what I have gathered the Yamaha [ratio of gasoline to oil mix] is a 100:1 and the Mercury [ratio of gasoline to oil mix] is 50:1. All the four-strokes I will assume get 10-percent less fuel economy with 10% ethanol blend. Does the two-stroke motor make more sense to use with ethanol? And if it does, would the 50:1 ratio be better combination? Is there a better midrange out there better geared for ethanol blend?
If my understanding of these engines is wrong please correct this rookie and set me straight.
Thanks in advance.
Tom W Clark posted 06-16-2006 10:53 AM ET (US)
Both the Yamaha and the Mercury should be run at 50:1 if premixed. If automatic oiling is used I would expect the oil consumption to be very similar.
I do not think that 10 percent ethanol fuel will reduce the fuel economy by 10 percent but regardless of that, whatever motor you choose will run whatever fuel you have available to you so it doesn't factor into the equation.
Peter posted 06-16-2006 12:39 PM ET (US)
The E10 diluted fuel blend has about 3 percent less energy content per gallon than undiluted gasoline. 4-strokes or 2-strokes have no known advantage when it comes to burning E10.
stubbleduck posted 06-16-2006 12:47 PM ET (US)
Thank you,
I guess I'm leaning towards that two-stroke Yamaha 70 over the Mercury 75- or 60-HP four-stroke. [The Yamaha 70] appears to be a good engine for this boat at a fair price. I guess I could even go with a 90-HP based on the weight. The 60-HP Mercury is a little more expensive and not as big. It probably gets better gas mileage though.
Again, I appreciate your your comments. Scott
sosmerc posted 06-16-2006 01:11 PM ET (US)
Given your selected options, I would go with the fuel injected Merc 60-HP Bigfoot four-stroke. I think it's one of the nicest running four-strokes (and I'm a two-stroke guy). You will certainly get better fuel economy and I would think it would be more forgiving with a diet of ethanol. The Bigfoot gearcase has a better gear ratio for torque and enables you to run larger diameter props...including a great selection of stainless models. You can raise the engine on the transom several holes for better speed and handling and reduced spray.
Would a 60 four-stroke be MY choice on a Montauk? Nope...I'd want a 90 or 115 Optimax.
stubbleduck posted 06-16-2006 01:35 PM ET (US)
Any idea on how the 60 bigfoot would compare in top speed compared to the 70 yamaha?
sosmerc posted 06-16-2006 01:56 PM ET (US)
Sorry, I don't have any "hard" facts regarding speed...but my guess is the 70 would be possibly as much as 5 mph faster.
The first time I ran a 60hp Merc four-stroke, it was on a small Dauntlass...and in my mind, I was comparing it to a 60hp Merc two-stroke...and thinking to myself, which engine would I want to own. The EFI gives the four-stroke very good throttle response, and that along with the 2:3-1 gear ratio, it has equal or better snap out of the hole compared to the two-stroke. It was quiet and smooth. Seriously, it is the first four-stroke I have run that I would even consider as a viable alternative to the two-stroke in that horsepower range.
The 60-HP four-stroke Mercury is a SmartCraft ready engine as well. Install a system monitor and you have all the info you need...or you can add link guages easily if there's something you like to watch at all times like oil pressure or engine temp. Very cool....don't think Yamaha has that...yet!
Peter posted 06-17-2006 09:40 AM ET (US)
The Yamaha 70 2-stroke is essentially as bullet proof as they come. It's simple, compact, light weight and packs a decent punch. Yamaha mechanics know how to work on them. It and the Yamaha 90 2-stroke have probably been the best selling motors in the world for the last 20 years.
I've got a 2003 on my 15 SuperSport and it has been absolutely flawless. The 70 is oil injected. Just pour oil in the under cowl reservoir every once in a while -- about a 30 second exercise. It even has a cap on the cowl so you don't have to take the cowl off to fill it up, which isn't very often in any case. Not having to deal with funnels, filters, filter wrenches, drain plug gaskets, waste oil containers, valve adjustments and inspections is a big plus for me.
As far as the average fuel consumption per operating hour goes (takes into account all operating speeds), the difference between a 70 2-stroke and a 60 4-stroke will be about 1 GPH. At $3.00 per gallon and a $1200 difference in price between a 70 2-stroke and a 60 4-stroke (see Ed's Marine Superstore for pricing example), you'll need to run more than 400 hours (about 8 years at 50 hours per year) before the purchase and fuel costs of the 70 catches up to the same costs for the 4-stroke. In that time frame assuming you are the average boater who runs not more than 50 hours per season, you'll have performed or had performed, 9 oil and filter changes with the 4-stroke. Some will argue that resale value is better on the 4-stroke and while that is true, the 4-stroke started out with a higher purchase cost so its resale value should be higher.
If you want a 4-stroke, get one because you want whatever the 4-stroke offers in terms of operating features such as quietness and are willing to give up the throttle response of a 2-stroke. Even at $3.00 per gallon gas, the operating economics alone still don't justify the purchase of 4-stroke outboards or even DFI 2-strokes in my opinion.

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Author	Topic: Mid-range Engines and Ethanol Fuel Considerations
stubbleduck	posted 06-16-2006 10:32 AM ET (US) Several of you may have tossed this around already and hopefully someone will get me up to speed or pose some thought or research ideas. I have narrowed my engine choices down to a Yamaha two-stroke 70-HP, Merc 75-HP Classic, or a Merc EFI 60-HP four-stroke. Much of this has to do with the [ratio of] weight to horsepower for my lighter weight 16-foot aluminum fishing boat. Now fuel economy is important, and typically I have always stayed clear of ethanol. I would like to start burning ethanol in my boat as I am from [New England] farmland, and most of us feel we need to make the conversion. From what I have gathered the Yamaha [ratio of gasoline to oil mix] is a 100:1 and the Mercury [ratio of gasoline to oil mix] is 50:1. All the four-strokes I will assume get 10-percent less fuel economy with 10% ethanol blend. Does the two-stroke motor make more sense to use with ethanol? And if it does, would the 50:1 ratio be better combination? Is there a better midrange out there better geared for ethanol blend? If my understanding of these engines is wrong please correct this rookie and set me straight. Thanks in advance.
Tom W Clark	posted 06-16-2006 10:53 AM ET (US) Both the Yamaha and the Mercury should be run at 50:1 if premixed. If automatic oiling is used I would expect the oil consumption to be very similar. I do not think that 10 percent ethanol fuel will reduce the fuel economy by 10 percent but regardless of that, whatever motor you choose will run whatever fuel you have available to you so it doesn't factor into the equation.
Peter	posted 06-16-2006 12:39 PM ET (US) The E10 diluted fuel blend has about 3 percent less energy content per gallon than undiluted gasoline. 4-strokes or 2-strokes have no known advantage when it comes to burning E10.
stubbleduck	posted 06-16-2006 12:47 PM ET (US) Thank you, I guess I'm leaning towards that two-stroke Yamaha 70 over the Mercury 75- or 60-HP four-stroke. [The Yamaha 70] appears to be a good engine for this boat at a fair price. I guess I could even go with a 90-HP based on the weight. The 60-HP Mercury is a little more expensive and not as big. It probably gets better gas mileage though. Again, I appreciate your your comments. Scott
sosmerc	posted 06-16-2006 01:11 PM ET (US) Given your selected options, I would go with the fuel injected Merc 60-HP Bigfoot four-stroke. I think it's one of the nicest running four-strokes (and I'm a two-stroke guy). You will certainly get better fuel economy and I would think it would be more forgiving with a diet of ethanol. The Bigfoot gearcase has a better gear ratio for torque and enables you to run larger diameter props...including a great selection of stainless models. You can raise the engine on the transom several holes for better speed and handling and reduced spray. Would a 60 four-stroke be MY choice on a Montauk? Nope...I'd want a 90 or 115 Optimax.
stubbleduck	posted 06-16-2006 01:35 PM ET (US) Any idea on how the 60 bigfoot would compare in top speed compared to the 70 yamaha?
sosmerc	posted 06-16-2006 01:56 PM ET (US) Sorry, I don't have any "hard" facts regarding speed...but my guess is the 70 would be possibly as much as 5 mph faster. The first time I ran a 60hp Merc four-stroke, it was on a small Dauntlass...and in my mind, I was comparing it to a 60hp Merc two-stroke...and thinking to myself, which engine would I want to own. The EFI gives the four-stroke very good throttle response, and that along with the 2:3-1 gear ratio, it has equal or better snap out of the hole compared to the two-stroke. It was quiet and smooth. Seriously, it is the first four-stroke I have run that I would even consider as a viable alternative to the two-stroke in that horsepower range. The 60-HP four-stroke Mercury is a SmartCraft ready engine as well. Install a system monitor and you have all the info you need...or you can add link guages easily if there's something you like to watch at all times like oil pressure or engine temp. Very cool....don't think Yamaha has that...yet!
Peter	posted 06-17-2006 09:40 AM ET (US) The Yamaha 70 2-stroke is essentially as bullet proof as they come. It's simple, compact, light weight and packs a decent punch. Yamaha mechanics know how to work on them. It and the Yamaha 90 2-stroke have probably been the best selling motors in the world for the last 20 years. I've got a 2003 on my 15 SuperSport and it has been absolutely flawless. The 70 is oil injected. Just pour oil in the under cowl reservoir every once in a while -- about a 30 second exercise. It even has a cap on the cowl so you don't have to take the cowl off to fill it up, which isn't very often in any case. Not having to deal with funnels, filters, filter wrenches, drain plug gaskets, waste oil containers, valve adjustments and inspections is a big plus for me. As far as the average fuel consumption per operating hour goes (takes into account all operating speeds), the difference between a 70 2-stroke and a 60 4-stroke will be about 1 GPH. At $3.00 per gallon and a $1200 difference in price between a 70 2-stroke and a 60 4-stroke (see Ed's Marine Superstore for pricing example), you'll need to run more than 400 hours (about 8 years at 50 hours per year) before the purchase and fuel costs of the 70 catches up to the same costs for the 4-stroke. In that time frame assuming you are the average boater who runs not more than 50 hours per season, you'll have performed or had performed, 9 oil and filter changes with the 4-stroke. Some will argue that resale value is better on the 4-stroke and while that is true, the 4-stroke started out with a higher purchase cost so its resale value should be higher. If you want a 4-stroke, get one because you want whatever the 4-stroke offers in terms of operating features such as quietness and are willing to give up the throttle response of a 2-stroke. Even at $3.00 per gallon gas, the operating economics alone still don't justify the purchase of 4-stroke outboards or even DFI 2-strokes in my opinion.