gas mileage

[Powder]

I've got a trip we're planning and I'm trying to do some comparisons on how much gas it will take.

How would you rank the following three motors for gas consumption from best to worst; 20 hp mercury 2 stroke, 60 hp yamaha 4 stroke and 75 hp Evinrude Etech?

Thanks for the help.

[delcecchi]

I'll play. Merc 20 is lowest because it is way smaller and thus can't burn more than a couple gallons per hour. Also doesn't go as fast.

Yamaha 60 would be my guess as second and etec 75 third, although there might not really be much difference. Too bad BWB went under. They used to have all sorts of "shoot outs" matching various motors.

[Powder]

I should clarify. The merc is late 90's model, the yamaha is a 2008 and the etech is a 2011.

[BobT]

I don't think you can make a valid comparison with the information provided. Same boat/load for all three? What is the motor rating of the boat? Are you comparing at WOT or idle rpm or somewhere between?

[MuskieJunkie]

It's less about the motor and more about the boat and weight it's pushing. However the fuel injected motors will get much better economy than the non fuel injected.

To answer your question, My guess from best to worst is:

Yamaha

Etec

Merc

[BobT]

pushing. However the fuel injected motors will get much better economy than the non fuel injected.

To answer your question, My guess from best to worst is:

Yamaha

Etec

Merc

[muddpuppy]

Well I have to agree it all depends on what it's pushing.

Up in Canada we travel to the same spots at the same time.

I have a 16' with a 50hp Yamaha 2 stroke My brother had a 18' Ranger with a 150 merc at the end of the week our gas bill was withing $10 of each other. Now I would have thought he would have doubled my gas consumption. But I run longer (slower) at WOT while he runs shorter (Faster) at 3/4 throtle.

[MuskieJunkie]

That's assuming the 60hp Yamaha is big enough to handle the boat.

Assuming the boat is rated for a maximum 75hp or more, I'd say the E-tec will do better than the other two because the other two would be under-powered for the load. The 20hp would barely put it on plane especially if there were more than one or two riders and will likely guzzle fuel pretty good as a result.

OK, that's why I said "my guess". I guess I don't see what you're getting at.

[delcecchi]

And if you had a 4stroke and ran at 3/4 throttle.....

[BobT]

And if you had a 4stroke and ran at 3/4 throttle.....

4-stroke or E-tec. According to my research a month ago the 2011 E-tec is comparable with 4-strokes of the same hp rating from mid-range up to WOT. At idle, the E-tec has shown to do even better than the 4-stroke by as much as 40%.

[BobT]

Quote:

OK, that's why I said "my guess". I guess I don't see what you're getting at

Fuel economy isn't only related to the size or type of motor. Put a 20hp motor on my boat and it'll drink fuel based on a gallons per mile rate simply because it would have to work too hard to move the boat. Gallons per hour may be entirely different especially if one doesn’t consider the distance covered. It goes without saying that the 20hp will use less fuel per hour than a 60hp or 75hp but the distance traveled would be considerably different.

Here are a couple examples to illustrate my point.

What kind of fuel economy do you suppose your car would get if you replaced the engine with the 3hp engine from your lawn mower? The engine probably wouldn't have enough horsepower to move the vehicle so mileage would be at or near zero miles per gallon. To solve this problem one could redesign the transmission with enough mechanical advantage for the motor so it can move the vehicle but the motor would be running at full throttle and you could probably walk faster. Fuel cost per hour would skyrocket.

When I first started farming I used a Farmall M rated at 33hp on the drawbar. I did my fall plowing with a 3-bottom 14” moldboard plow. The tractor typically consumed about 3 gallons of fuel per hour and I could till up about an acre per hour moving in 1st gear at 2.6mph. It could only pull that plow in first gear. Later I picked up an Allis-Chalmers rated at 90hp on the drawbar and a 4-bottom 16” moldboard plow. I plow about 2-1/2 acres per hour in 4th gear at about 4.3mph. Any faster would potentially damage my plow. This tractor typically uses about 2-1/2 gallons of fuel per hour. That’s a 15% fuel savings per hour even though the Allis is three times the horsepower.

This is a bit deceiving because if you noticed it turns out that the gallons per acre remained virtually unchanged so let’s consider this in relation to our boat scenario. We’re putting all three motors on the same boat so let’s consider putting both tractors on the same plow.

If I hook that 4-bottom plow to my M, I am willing to bet my next pay check that I will get zero acres plowed per gallon of fuel because the M won’t be able to even move the plow. Now, put the 3-bottom plow on both tractors. The Allis uses at least 15% less fuel per hour and can easily move 65% faster. Again, due to potential damage we’ll stay in 4th gear although it could go faster. Now, instead of plowing 1 acre per hour on 3 gallons of fuel, I would plow 1.65 acres per hour on 2-1/2 gallons of fuel. That’s a fuel savings of about 17% per hour and about 53% per acre despite the tractor being 3 times the horsepower. Note that this does not consider the fact that the Allis would not be loaded nearly as much as it was using the 4-bottom so its fuel consumption should actually be even better.

[MuskieJunkie]

OK whoa. Like I said originaly, it's more about what it's pushing than the motor. Take it easy homeboy.

[Powder]

Thanks for the replies. My question was meant to assume all motors were used on boats they were appropriately rated for.

[delcecchi]

Then I would be pretty sure a 14 or a light 16 foot boat, the classic "resort boat" with the 20 will get better mileage. Small boat easier to push. The ultimate is a canoe with a 2hp on it. Go 20 miles on a gallon of gas.

[BobT]

Then I would be pretty sure a 14 or a light 16 foot boat, the classic "resort boat" with the 20 will get better mileage. Small boat easier to push. The ultimate is a canoe with a 2hp on it. Go 20 miles on a gallon of gas.

That would be my choice.

[BobT]

OK whoa. Like I said originaly, it's more about what it's pushing than the motor. Take it easy homeboy.

You asked. Just thought I'd explain where I was coming from.