Which gets better mileage?

Expidia

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So I've located my second boat, but it's not the one I want.

If I take this one to hold me over until I find the exact boat I'm looking for (I'm looking for an out board not the I/O).

So this one is an I/O with the Merc 4.3

I'm thinking I might buy this one and resell it after I finally locate the one I want.

The one I want will probably come with a Merc 150 Optimax 2 stroke.

Once I find the exact boat I want, I plan to swap whatever outboard that's on it for a Merc Verado 200hp. I first want to see how it handles with the 150 Optimax.

So here is my question:

What type of mileage/fuel burn at various speeds, can I expect from:

The Merc 4.3 I/O

Merc 150 2 stroke

Merc Verado 200hp

thx
 

tashasdaddy

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Re: Which gets better mileage?

the 4.3 is going to burn just a little more than the 150, and less than the 200.

1 gallon per hour, for each 10 hp of rating, at wot.
 

45Auto

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Re: Which gets better mileage?

Tashadaddy is right IF you run at wide open throttle ALL the time. At cruise speeds (30 MPH or so) the Optimax will probably get about 5 MPG on a typical 19-20 foot boat vs around 4 for the Verado.

Lots of boat tests of these engines on the Mercury site, check it out for yourself:

Optimax 150:
http://northamerica.mercurymarine.c...=Title&Section=outboardChecks&optimax135175=6

Verado 150:
http://northamerica.mercurymarine.c...=Title&Section=outboardChecks&fourCyl135200=3

A typical 4.3 I/O on a 19' bowrider gets from 5 MPG on a Glastron to 6 MPG on a Doral, per Boattest.com. You can sign up there (free) with just an email address.
 

Silvertip

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Re: Which gets better mileage?

I'll add two points. 1) with engines of that size if you have to worry a great deal about fuel economy you perhaps should rethink boating as your main recreation. 2) All boats have a sweet spot for economy and once on plane, more throttle = lower MPG. Less throttle = better MPG just like in your car. However, WOT vs cruise (or anything less than WOT) means you have to travel longer at that speed to reach your destination. That extra run time requires fuel. Is it the same either way? No - less than full throttle will save fuel but if you had a flow meter and calculated the savings, you likely be surprised how little difference there really is. Now if you have no particular destination in mind and are just out for the sake of being out then speed and MPG are sort of non-factors. Lastly, compared to the Opti, the Verado weighs a ton.
 

45Auto

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Re: Which gets better mileage?

However, WOT vs cruise (or anything less than WOT) means you have to travel longer at that speed to reach your destination. That extra run time requires fuel. Is it the same either way? No - less than full throttle will save fuel but if you had a flow meter and calculated the savings, you likely be surprised how little difference there really is.

Don't need a flow meter. That's why fuel economy is calculated in miles per gallon, it takes the time factor (miles per HOUR and gallons per HOUR) completely out of the equation. For example, you can easily see from here:

http://northamerica.mercurymarine.c...=Title&Section=outboardChecks&optimax135175=6

that the Ranger gets 5.1 MPG at a 32 MPH cruise, and 3.4 MPG at 48 MPH WOT. It'll obviously take you 50% longer to get where you're going at 32 MPH rather than 48 MPH, but you'll use 1/3 less fuel. You'll have to decide whether saving 1/3 of your fuel costs is significant or not.
 

Silvertip

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Re: Which gets better mileage?

Oh crap -- here we go again. Fuel flow is definitely NOT taken completely out of the equation because without the flow meter or a fuel management system you have no idea how much fuel you are burning at any given speed which is what the chart you reference shows. How do you think those numbers were arrived at? Fuel flow/fuel management systems allow instantaneous readout (how much fuel is burned at that speed). Yes -- that number (speed and gallons per hour) allow computing MPG. So you just contradicted yourself. Without either of those systems you would need to run x amount of time (and very consistently I might add), then stop, refuel to determine how much fuel you burned (very accurately of course). Calculate MPG and then repeat the process for the next speed. No testing group in this day and age calculates mpg that way because it would take many hours to complete a chart like this and then it would be very inaccurate. This chart was probably completed in about 45 minutes of testing with no refills. They set throttle for a test speed 8.3 mph for example), looked at the flow meter (2.12 at that speed). Divided 8.3/2.12 and by golly that comes to 3.9 MPG. That's why that GPH column is there. If you take a 100 mile trip and then fill up you can determine MPG but that number is an average across all speeds you traveled during the trip. Any deviation from a fixed speed skews the numbers. You used 32 MPH and 48 MPH (5.1 MPG and 3.4 MPG respectively) as saving 1/3 of a fuel load. Saying it saves 1/3 of the "fuel load" is accurate only if you indeed ran a full fuel load. What I'm suggesting is that if consider the actual amount of fuel burned at WOT vs the actual amount of fuel burned had you cruised at a slower speed, one might find the difference of minor significance. Others might consider it a big deal. Another way to look at the same chart is to say 10 MPH (37.3 to 47.7 MPH only costs me one tenth of a MPG. On a 100 mile excursion, do you consider that significant? Some would - some won't. But my consideration would be in that 100 mile trip I would get back to the dock roughly ten minutes earlier at WOT. And finally, I'm sure you picked a chart that provided numbers that matched your feelings on MPG. I've posted "many" charts that show nowhere near 1/3 difference in WOT MPG vs cruise MPG>
 

Expidia

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Re: Which gets better mileage?

Thx for all the replies. The reason I asked this question was because it seemed to me that since the weight of the inboard is pushed forward, one would think the I/O would plane quicker and use less gas to get up there.

Seems with all the weight of an O/B hanging off the transom that an I/O might be more efficient gas wise.

I don't drive wide open, unless I'm outrunning some weather. Mostly cruising speeds.

I just was tossing around the thoughts of $5.00 a gal at the marinas again probably sooner than most think. Sales of new hybrid cars are already down by 60% because gas is just over $2.00 a gal. This is a recipe for higher fuel costs down the road especially when the economy heats up and demand rises.

I'd like my other (larger) boat to be as fuel efficient as possible, just on principle.

I might have to live with an Optimax for a short time, since it will most likely be the one on the used boat.

The Verado's are 510 in weight for the 150, 175 and 200, so the 200 is a no brainer for my tastes! I also like the cable-less electronic controls on the new Verado's.

But If the I/O was hands down more efficient, I might have started looking in that direction. From the responses and the tests links it's probably pretty close. I know personally, I really don't want to own an I/O anyway if I have a choice because I love outboards . . . what can I say!
 

FlyinGuy1017

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Re: Which gets better mileage?

Just out of curiosity, why is everyone so hung up on MPG? In boats, it is impossible to figure an accurate MPG, turn 90 degrees, and have the same MPG for the same throttle input.

Fuel calculations should be made in GPH, ideally with currents, weight, RPM, trim setting, pressure altitude, tempreture deviation from standard, water surface conditions, and wind factored.:eek: Since none of this is possible outside of controlled conditions, it is best to just figure your average GPH for different power settings. There are too many other factors involved to base calc's on MPG. i.e. go up river and turn around; time, distance, and fuel consumption are much different for the given runs.
 

Expidia

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Re: Which gets better mileage?

Ooops, I guess I was posting my thoughts and missed those last two posts.

Thx for the in depth explanations but I've been through those Outboard efficiency sites before and take them with a grain of salt because I know Merc, Yamaha, Etec etc can skew their results since they are each trying to sell you on their product.

I don't want this thread to get too far off track.

My reason for asking was just a comparison of I/O to O/B since the HP's were somewhat close when comparing the Verado 200 hp O/B to the 4.3 Alpha or Bravo I/O which are both around 220 hp.

510 is still a lot to hang off an aluminum boat IMO. But the 200 probably would not need tabs. I'm not overly impressed by 2 strokes, Optimax or the Etecs (it's 524 lbs for the long shaft Etec anyway).
 

tashasdaddy

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Re: Which gets better mileage?

an inboard/outboard hull is totally designed differently, than an outboard hull. they are 2 totally different animals, even though the exterior may look alike.
 

45Auto

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Re: Which gets better mileage?

Wow, talk about reading between the lines!! Don't have any idea how Silvertip managed to interpret my earlier post like he did! :)

Silvertip, Post #6:
without the flow meter or a fuel management system you have no idea how much fuel you are burning

If I had an 18' Ranger with an Optimax like we were using as an example (or any of the other THOUSANDS of boat/engine combos that have been tested and published ...) I could come so close it doesn't matter by looking at the existing curves and tables. :)

My first boat was a 120HP outboard with no instrumentation at all. No flow meter, fuel management system, speedometer, etc. But it had a 24 gallon tank and had to be filled up every 4 hours when we were skiing and tubing. As you can hopefully figure out, it was burning 6 GPH.

Silvertip, Post #6:
How do you think those numbers were arrived at?

I have no need to make guesses how they were arrived at. Either you accept the data as valid or you don't. Methodology doesn't matter, the numbers are the same IF DONE CORRECTLY no matter how you do it. Are you trying to say the Mercury tests aren't valid unless they do it like you say??? I can think of at least 4 ways to get the raw data without even trying. You need some combination of distance, time, and fuel volume. MPH is distance & time, GPH is volume & time, and MPG is distance and volume. Given any 2 you can derive the other.

Silvertip, Post #6:
They set throttle for a test speed 8.3 mph for example), looked at the flow meter (2.12 at that speed).

LMAO. Try applying a little logic in your guesses. Notice how the 8.3 MPH is 2000 RPM? Notice how the next step is 21.1 MPH at 3000 RPM, and the previous one is 4.7 MPH at 1000 RPM? If it really mattered, I would bet that they set the throttle for the even RPM increments and took whatever speed (MPH) and fuel volume (GPH) they got at that particular RPM.

Silvertip, Post #6:
You used 32 MPH and 48 MPH (5.1 MPG and 3.4 MPG respectively) as saving 1/3 of a fuel load. Saying it saves 1/3 of the "fuel load" is accurate only if you indeed ran a full fuel load.

Please re-read my post and try to find ANYWHERE that I said ANYTHING about "fuel load". It is a fact, whether you like it or not, that if you travel the same distance at 3.4 MPG and at 5.1 MPG, at 5.1 MPG you will use 2/3 of the fuel you would at 3.4 MPG. Has NOTHING to do with "fuel load", doesn't matter if you go 50 feet or 5000 miles. You will still use 2/3 the fuel.

Silvertip, Post #6:
And finally, I'm sure you picked a chart that provided numbers that matched your feelings on MPG.

Why are you so vehement that everyone is out to get you?? Nobody needs to cherry-pick the data to blow you out of the water. I used the first chart with a 150 Optimax from the list at Mercury. Here's the link, it's not hard to check.

http://northamerica.mercurymarine.c...utboardChecks&fourCyl135200=3&optimax135175=6

I have no "feelings" on MPG. MPG and GPH are derived functions. MPG is distance per volume, GPH is volume per time. MPG doesn't have a time term, GPH doesn't have a distance term. In some cases one is more useful than the other. If you're talking about mileage, MPG is the function that describes what you are interested in. Look at the title of the thread!!!!

Which gets better mileage?

Read the original posters question:

So here is my question:

What type of mileage/fuel burn at various speeds, can I expect from:

You can tell him that at 30 MPH he will burn 10 GPH. Or you can tell him that at 30 MPH he will get 3 MPG. Exact same thing in both cases. If fuel economy is what is important to him, then the info he is interested in is that the Optimax gets about 5 MPG at best cruise, and the Verado gets about 4 MPG at best cruise. Can MPG be determined using GPH and speed? Yes! Can GPH be determined using MPG and speed? Yes! Can speed be determined using MPG and GPH? Yes! It's just a set of variables. No significance to any of them except in relation to what you're interested in.

Silvertip, Post #6:
I've posted "many" charts that show nowhere near 1/3 difference in WOT MPG vs cruise MPG>

You may have, I don't cruise the Internet looking for posts by you. Please provide links for further discussion. Talk is cheap, this is the Internet!
 

Utahboatnut

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Re: Which gets better mileage?

One other thing to think about that I haven't seen yet is the oil consumption of the optimax, depending on what oil you like it can really add up to the price of each gallon of gas you burn. If you use the cheapest stuff out there its not AS bad but start going with a good synthetic at 40.00+ per gallon and it can start to add up in the total price of fuel costs. My last boat had a 200 evinrude on it and I rarely traveled at WOT and it was plenty thirsty add in the oil and it was easily as expensive as my V8 I/O that I have now is to run. I did like the outboard though it sure was easier to winterize,waterpump etc. But I also like the V8 I don't have all those carbs to worry about, parts are cheap, and around here there are plenty of people who work on them as opposed to the outboard which most here avoided like the plague..
 

45Auto

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Re: Which gets better mileage?

Oh no, please don't bring O/B vs I/O into a MPG vs GPH thread! Next thing you know someone will be wanting to know which oil is best ......:)
 

Silvertip

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Re: Which gets better mileage?

Lets get some clarity to the discussion before I respond further. My first response in this thread was to add two points: 1) boat fuel economy is really bad and if one must be overly concerned about it, boating is perhaps not the best recreation to chose. In this economy you certainly can't argue with that and it was intended to catch the eye of first time boaters. 2) I indicated that if one figured out what the real difference was between cruising and running WOT to a particular destination, the fuel savings may not be as great as expected. This is were the discussion train has in the past and again in this case, ran off the tracks. My suggestion that if one had a flow meter and calculated the true MPG one might be surprised to see how little difference there was in cruise vs WOT cost. That comment was taken by "45" as the only way to figure this out. It is however the only way to do it accurately and without the result being an average (average being the operative word).

I fully qualified the "difference" as a "value measurement". If time is important to you, it overrides MPG. If MPG is important to you then it overrides "time". Only you can decide what is most important. As for the fuel "load" response -- I apologize -- I did misread your comment. While 1/3 ratio is fairly common one needs to define what cruise speed or cruise rpm is. I went to the Yamaha site and grabbed a 150 TXR test on a 19 foot Sylvan. At 2000 rpm the MPG was 2.21 off plane (9.3 MPH). At WOT the MPG was 2.98 but at 52.1 MPH. Since in this extreme case the savings in time is obvious (nearly four times faster), there is a fuel savings as well although it is very small and only if your cruise speed is 9.3 MPH. 3000 RPM yielded 3.9 MPG at 25.6 MPH so that is a more realistic cruise speed. Comparing that to WOT yields 25% fuel savings. So you see, numbers are what you make them. Accuracy is what makes them useful.

I said: Without the flow meter or a fuel management system you have no idea how much fuel you are "burning"! It's a simple fact that you don't - at least not until the trip is over. You then refill, measure and calculate and then it's an average. In that case it is how much fuel you "burned". Hence the value of the flow meter which provides instantaneous flow rates which then allows very accurate data points on the chart you posted. So in the example of your 120 HP outboard, what was your MPG at 20 MPH, or 3000 RPM, or WOT or what was your burn rate at 1000, 2000, or any other RPM. All you know is that in the amount of time you ran, whatever speed you ran, whatever load you had, over four hours you "averaged" 6 GPH. In this case you have flow rate but without distance and time you have no idea and cannot plot a respectable chart. And this is were we disagree over a very simple concept.

If that's a close enough measurement for you who am I to say you are wrong? That's not what I'm trying to do. I do try to show that for accurate and instantaneous values for any data point, instrumentation is required. For those boaters who never lose sight of land MPG or GPH at any rpm is probably of no concern whatsoever. To those who do cover great distances, accurate and immediate numbers are very important.

Glad you had a good laugh, but you are laughing at yourself. I was using the 8.3 number as a relationship to GPH and MPG in a simple math problem. Obviously one would not pick 8.3 MPH as a data point (unless one used GPS). It just so happens that even rpm is used as the data point and 8.3 mph is the result of that rpm. On another boat (even the same boat but with a different prop) that column would have very different numbers. My point here was to show that speed divided by GPH yielded the listed MPG figure "at that throttle setting" which in this case was 2000 rpm. I could have picked any other pair of numbers in the chart.

I made no assertion that Mercury was skewing their tests. I merely "suggested" that you might have searched for and picked a chart that showed a 1/3 difference between cruise and WOT fuel burn. If you didn't - great. If you did - no big deal, it fit your arguement. That's why they call it debating.

Summary: We agree in principle as we generally have -- we disagree on accuracy and its value.
 

CATransplant

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Feb 26, 2005
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6,319
Re: Which gets better mileage?

Well, in a way, none of this matters, really. When you get to the big boat go fast stage fuel mileage discussions are a waste of bandwidth.

Big go fast boats use lots and lots of fuel. If you have a really fat wallet...fat enough to afford a big go fast boat, then you can afford to buy fuel for it.

If you can't afford to buy fuel for it, it will sit in your driveway and fuel economy won't be an issue.

The difference in cost of operation between 3 mpg and 4 mpg is just one factor. There are many others. Either one, though, is going to suck money out of your wallet and burn it up.

Got bucks? Go fast. Don't got bucks? Get a small boat and go slower.
 

Expidia

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Re: Which gets better mileage?

One other thing to think about that I haven't seen yet is the oil consumption of the optimax, depending on what oil you like it can really add up to the price of each gallon of gas you burn. If you use the cheapest stuff out there its not AS bad but start going with a good synthetic at 40.00+ per gallon and it can start to add up in the total price of fuel costs. My last boat had a 200 evinrude on it and I rarely traveled at WOT and it was plenty thirsty add in the oil and it was easily as expensive as my V8 I/O that I have now is to run. I did like the outboard though it sure was easier to winterize,waterpump etc. But I also like the V8 I don't have all those carbs to worry about, parts are cheap, and around here there are plenty of people who work on them as opposed to the outboard which most here avoided like the plague..

Thx, you raise many good points here. I certainly don't want to turn this thread into 2 stroke vs 4 stroke. But I was interested in 4 stroke vs I/O.
I just don't want to give up any deck room and the O/B hanging off the bracket really maximizes the much needed deck space on a 22 footer.

I won't deal with carbs anymore and that's why I go the EFI route. That Opti would only be on the boat for the shortest time possible because the step up to a new 200 Verado is going to be a major hit on my wallet after probably 25-30k for the boat and another 12-15k for another tow vehicle.

Funny you mention the oil thing. I was walking through Walmart's boat section just yesterday and was looking to pick up a gal of Quicksilver oil for my 4 strokes and I first grabbed this gal that said $28.95 and it was for strokes. I said to myself, glad I don't have to use this stuff on top of each gal of gas.

Etecs tout low maintenance and that's probably true. But for me changing the plugs and filters on my 4 strokes and the occasional valve adjustments,
I think these new EFI are an electronic thing of wonder when compared to my long line of previous outboards.

I get a 5 year warranty anyway as they are so costly to repair and I never plan on keeping "any" outboard beyond 5 years.

2 stroke vs 4 stroke . . . to each his own, this is what makes the world go around as to personal tastes.

I really enjoy seeing Etecs on someone else's boat. They really are a thing of beauty, especially the white ones. It's just I'd prefer seeing trip Verado's on my own boat, while I'd be cruising around off the coast like Newport RI, Florida or CA. I can dream can't I?
 

Expidia

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Re: Which gets better mileage?

an inboard/outboard hull is totally designed differently, than an outboard hull. they are 2 totally different animals, even though the exterior may look alike.

I thought the hulls were the same other than the I/O bellows coming out of the rear.

That would make sense as to why there would be a diff in the performance being they are both equal hp's.
 

rrhodes

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Re: Which gets better mileage?

Just strap 20 of these to your boat. Problem solved. TORQEEDO CRUISE R: With the thrust of a 10 HP internal combustion outboard. Now how many Batteries will you need?

Cruise%202.0%20R_4.0%20R_05062008_3.jpg
 

Expidia

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Re: Which gets better mileage?

Thx 45auto, this was just the input I was looking for below that you posted:

Which gets better mileage?

Read the original posters question:


Quote:
So here is my question:

What type of mileage/fuel burn at various speeds, can I expect from:

You can tell him that at 30 MPH he will burn 10 GPH. Or you can tell him that at 30 MPH he will get 3 MPG. Exact same thing in both cases. If fuel economy is what is important to him, then the info he is interested in is that the Optimax gets about 5 MPG at best cruise, and the Verado gets about 4 MPG at best cruise. Can MPG be determined using GPH and speed? Yes! Can GPH be determined using MPG and speed? Yes! Can speed be determined using MPG and GPH? Yes! It's just a set of variables. No significance to any of them except in relation to what you're interested in.

Expidia says: great to the point response!

TD's response was very helpful too in that the hull of O/B has a different design than the I/O as to why 200-220 O/B vs I/O can have diff MPG burn factors.

So the guy with the 2nd choice of boat design that I found for sale finally called back a few days later (to me this was not good either, many times they are still fixing an issue with the boat). Said it's been for sale since last fall. He can't be in too much of a rush to sell it because it took him several days to return my call. I left my original message that I'll be there the next day to give him a 5k deposit. Usually, when you sell a boat you might only get one call and that's the one who takes it. When I sell a boat I stay glued to me cellphone.

I say 2nd choice because his was the I/O design which would cost me much needed deck space. Big fiberglass boats have the power plant behind the back seat and below deck. I would have taken it and flipped it as soon as I found the model I wanted (O/B mounted off the exterior bracket). But after spring, it becomes a tough time to sell a boat. He had dropped his price from 20,500 down to 18,500 in his next ad. But I looked it up in the used boats book and 18,000 was the average selling price anyway.

For me to flip it fast I'd have to buy it for at least 3k under the average.

I might have tried to talk him down but I had already changed my mind about the I/O design. Also, his ad said it has downrigger plates on the back. That would be OK if he trolled with an auxiliary motor. But I asked him if he did that and he said he just used a trolling plate that hangs over the prop :eek: and he had no issues.

That statement was the deal breaker for me since I'm not touching an I/O that's been trolled at 1-2 mph for hours on end for the past 3-4 years. You can do this with the newer EFI computer controlled outboards as they won't load up like a carbed model. But I use a 9.9 aux or a Minn Kota electric for trolling anyway. I wouldn't troll with a large O/B since I prefer to treat them better.

Lastly, even the seller had commented to me when he knew I had already changed my mind and continue my search for an O/B model, he said if he had it to do over, he loved everything about the boat but he missed having that extra deck space freed up.

Another reason I want the O/B bracket design is that I plan to have a custom enclosure made up that goes all the way to the back of the boat (a camper top style) this will give me an enclosed salon area, when I'm hanging out over night at various marina's during my cruising trips. I won't have to be relegated to a tight cuddy to spend my time.

So my search continues . . . I'm in no rush since I still have the Lund to use. I just put the final coat of black on the props that I painstakenly refinished, yesterday. Installed the no feed back steering. She's all ready now to just ADD THE WATER :D
 

fishingdan

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Feb 12, 2005
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1,045
Re: Which gets better mileage?

I'll try to find it an post the article, but I can't find it at the moment.

Boattest or one of the boating mags did an article a couple of years ago comparing a 4 stroke outboard, an optimax and a mercruiser I/O. All were the same hp. They tested performance and fuel economy. The I/O was the surprise winner in economy edging out the others by a small margin.

My latest boat has a mercruiser 4.3 I/O. I love it. Maybe it is just a change of pace from an outboard, but it is working for me. I have always had and like outboards (still do - more room in the boat).
 
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