4 Stroke or 2 Stroke, which is more fuel efficient?

[Lucius]

So I have been day dreaming about the next boat I want to buy. I will probably have to sell my body for the next 1 to 2 decades before I could afford one of these boats, but that has never stopped a man from buying a new toy. I was thinking that I would get the Lund 1775 Pro V. And while I was doing some research on some motors, another boat came into my liking to the point where I can't decide between the two now. That is the Lund 1775 Impact. And the reason this 1775 impact came into my like is that when powered by the 115 optimax, it is damn near as fuel efficient as my 25 hp fourstroke I currently have on my lund wc 16 dlx now. I then looked at the 115 fourstroke and thought if the optimax is awesome, what will the fourstroke be and much to my amazment the fourstroke was no where near as efficient.

The efficiency with the lund 1775 pro v is also nowhere near the lund 1775 impact with the 115 optimax and slightly less than the 115 fourstroke.

http://www.mercurymarine.com/engines/en ... in/?ID=489&" onclick="window.open(this.href);return false;

http://www.mercurymarine.com/engines/en ... in/?ID=585&" onclick="window.open(this.href);return false;

[G-Man]

I'd call BS on the Optimax performance specs. Yes, they get excellent fuel economy, but those numbers look a bit too good. I'm not familiar with the inner workings of the Optimax, but the Etec provides a computed GPH reading that your GPS enabled sonar unit can convert to MPH. The computed GPH is just that, computed, and should not be considered accurate without verification. The same will apply to the any computed fuel usage device, including aftermarket fuel flow meters. Also, having the right prop size and pitch for your boat and motor combination is a major factor in performance. This is where knowing your dealer pays dividends. A good dealer will water test the boat with several props on hand and swap them around to determine which provides the best performance.

[hewesfisher]

Optimax performance isn't BS G-Man, it's real and it's accurate. Set up for most optimum trim and rpm, full tank (48gals) and our normal full gear load, 2 people and our 70lb yellow lab, I have actually exceed 7mpg with my 150hp Optimax, so it wouldn't surprise me a bit to see better performance from a smaller Opti on a lighter boat.

Combined with GPS and a SmartCraft instrument (several choices here) you will see extremely accurate fuel consumption. Per Mercury, ECU reported fuel consumption accuracy is within 2% and this applies to all SmartCraft capable motors. Having used a MercMonitor for the past 2 1/2 yrs, I can tell you I am always within a half gallon of reported consumption when I refuel. Not speculation, real world numbers with my Optimax.

[Bodofish]

I gotta say the Merc's have some pretty darn impressive numbers these days. Just because they don't say E-Tec on the side doesn't mean they aren't computer controlled. All of the modern OB are totally computer controlled and injected. Even my buddies little 25 jet that runs without a battery is fuel injected and computer controlled. I'll say it again, you can't go wrong with any of the big guys new offerings. With the latest manufacturing techniques and QA programs all of them are making top notch motors, the brand loyalty is just silly, it's really the shop you need to pick.

[Lucius]

I'd call BS on the Optimax performance specs. Yes, they get excellent fuel economy, but those numbers look a bit too good. I'm not familiar with the inner workings of the Optimax, but the Etec provides a computed GPH reading that your GPS enabled sonar unit can convert to MPH. The computed GPH is just that, computed, and should not be considered accurate without verification. The same will apply to the any computed fuel usage device, including aftermarket fuel flow meters. Also, having the right prop size and pitch for your boat and motor combination is a major factor in performance. This is where knowing your dealer pays dividends. A good dealer will water test the boat with several props on hand and swap them around to determine which provides the best performance.

I have to agree on having the proper blad and pitch to match the motor and boat you are using as they have many tests that show the same motor, just with a different blade and it can make quit a bit of difference. Much to my surprise the verado and Proxs seem to be less fuel efficient than the standard fourstrokes and optimax's with minimal increase in MPH!!

[hewesfisher]

Much to my surprise the verado and Proxs seem to be less fuel efficient than the standard fourstrokes and optimax's with minimal increase in MPH!!

Both the ProXS and Verado are high performance outboards. You can't add a supercharger to a NA engine and not lose fuel efficiency, so no surprise there. The ProXS models are "pumped up" Optis with prop shaft hp near the upper limit of the 10% range allowed by EPA. Matter of fact, the 2013 250 ProXS has been detuned to meet new EPA rules.

Those who buy the high performance outboards aren't really interested in fuel efficiency, and they run those motors at or near max rpm all the time. I'm amazed at how much money the bass boat guys spend to gain just a couple mph in top speed. I guess every ounce of performance counts when tourney fishing. Reminds me of the old drag racers adage, "Speed is money, how fast do you want to go."

[Bodofish]

I might add anyone who buys a boat looking for fuel efficiency is the person who is never going to be happy on the water. If you're splitting hairs on mileage, don't buy a boat, it's a bad idea for you.

[TroutSnipr]

Having been the "first to the hole" tourney bass guy for a lot of years with a Bullet 21XDC(arguably one of the fastest bassers on the water 100mph+ EASY)From Nixon's in Walla Walla with both Merc 300 Pro XS and massaged offshore Yami VMax power at one time, all I can say is unless you are regularly making the finals at big southern tour tourneys or just have money to burn, the newer 4 strokes are really the way to go. Easier maintenance, better mileage, smoother power, better longevity etc than even the best 2 strokes. Even with cleaner burning 2 strokes, I still think with in a few more years they are going the way of the dinosaur, and it'll be 4 strokes only (except maybe for racing use only).

[Lucius]

Much to my surprise the verado and Proxs seem to be less fuel efficient than the standard fourstrokes and optimax's with minimal increase in MPH!!

Both the ProXS and Verado are high performance outboards. You can't add a supercharger to a NA engine and not lose fuel efficiency, so no surprise there. The ProXS models are "pumped up" Optis with prop shaft hp near the upper limit of the 10% range allowed by EPA. Matter of fact, the 2013 250 ProXS has been detuned to meet new EPA rules.

Those who buy the high performance outboards aren't really interested in fuel efficiency, and they run those motors at or near max rpm all the time. I'm amazed at how much money the bass boat guys spend to gain just a couple mph in top speed. I guess every ounce of performance counts when tourney fishing. Reminds me of the old drag racers adage, "Speed is money, how fast do you want to go."

Well in some instances it means nothing but a less fuel efficient motor. Check out the 150 four stroke as compared to the 150 verado. The standard 4 stroke is faster accross the board...on this boat...

http://www.mercurymarine.com/engines/en ... in/?ID=588&" onclick="window.open(this.href);return false;

http://www.mercurymarine.com/engines/en ... in/?ID=773&" onclick="window.open(this.href);return false;

Now I know there are multiple variables that come into play that could have an effect on these two performances, but when you purchase a supercharged motor, you expect to get alot more out of it....not get beat by the stock motor!!

[Bodofish]

Horse power is horse power regardless of whether it's a two, four stroke, normal or pumped. Makes no difference how it's made. I would venture to say any big bull dozer you point at is super charged and turbocharged, yet you won't see them at a drag strip anytime soon. It's just a measure.

[Lucius]

Horse power is horse power regardless of whether it's a two, four stroke, normal or pumped. Makes no difference how it's made. I would venture to say any big bull dozer you point at is super charged and turbocharged, yet you won't see them at a drag strip anytime soon. It's just a measure.

I would agree with you 100% on your comment, however when the 115 optimax on a lund 1775 impact is damn close to the same fuel effeicieny of a 25 or 30 hp fourstroke on a little 16' lund dlx fishing boat....that is game changing right there and that is the only reason I am now considering getting the 1775 impact with a 115 optimax... I forgot to post the 30 hp fourstroke but here it is as the 1775 impact data is posted in my original post.

http://www.mercurymarine.com/engines/en ... in/?ID=489&" onclick="window.open(this.href);return false;

http://www.mercurymarine.com/engines/en ... in/?ID=251&" onclick="window.open(this.href);return false;

[Bodofish]

Once again, don't buy a boat because of the fuel your going to save. It just doesn't happen. Fill it up and run it till you have to fill it again and don't look back. Boats are not about saving money in any way shape of form.

Bust Out Another Thousand

[TroutSnipr]

Horse power is horse power regardless of whether it's a two, four stroke, normal or pumped. Makes no difference how it's made. I would venture to say any big bull dozer you point at is super charged and turbocharged, yet you won't see them at a drag strip anytime soon. It's just a measure.

This is wholly not true (and not directed at you Bodo). There is no real figure known as "horsepower". It is a function of torque derived over time in this case RPM. This is where people talk about "holeshot" vs "topend". Every motor makes an equal amount of torque and 'horsepower' at 5252 rpm(not meaning all engines per se but that a specific motor will make the same hp and torque at 5252rpm). The bulldozer makes thousands of ft/lbs of torque but almost no horsepower because the motors do not rev above maybe 2k rpm. This is the same for semi trucks. So an engine that makes its peak 200hp at 2000rpm vs a motor that makes its peak 200hp at 7000rpm is going to be a totally different beast.

This is also the reason that small displacement import motors do not make a lot of torque but can make a lot of horsepower because they barely start to make power at 3-4k rpm and redline out at 8 or 9k rpm vs a big block chevy that makes a ton of torque and hp because the motor redlines at 6k rpm. In cars a lot of this plays out with high stall torque converters, multi-speed overdrive transmissions etc, in order to maximize the power you have to work with.

In boats its a lot different and has more to do with hull shape, motor placement(via trim and jack plates), and blade count, prop pitch etc. So the hull type, typical load/capacity, pad length, transom depth, motor mount position, weight balance etc will have a huge affect on what motor works well on a particular boat. That is why you so often see people changing to a 4 blade prop to get more bite in the water, however the prop change places more load on the motor and it will no longer rev as high as it did with the 3 blade. So then people will drop to a 4 blade with an inch less pitch to try and get the RPM back etc.

Its all a balancing act, and until I see a trustworthy independent third party run everything on a dyno under closed scientific conditions I don't drink anyone's kool-aid.

Here is a real good article on props though...

http://www.propellerworld.co.uk/Prop_Ba ... s_wor.html" onclick="window.open(this.href);return false;

[Bodofish]

Horsepower is a very real, but in the strictest sense it's a measurement of projected work done. It's extrapolated from the power produced. Not to mention for the last 70 years or so it's been the defacto measurement of power produced by any gasoline engine. Diesels on the other hand are normally measured in KW.

so I say again, horsepower is horsepower. What you choose to do with it is your thing. Gear it low for the hole shot or gear it high for the top end, makes no difference, 150 HP is still 150HP.

[fear_no_fish]

If your going to have to "sell your body" just to get a new boat, and you have one already. You really shouldnt be worried about a couple bucks of gas each trip. Maybe get a row boat?

It was just said above, Bust. Out. Another. Thousand.

[angry john]

It seems to me that the answer is quite simple and maybe were over thinking it a little. A four stroke engine is more efficient and produces better mpg for the same HP but weighs a lot more and has more moving parts. In racing weight is everything, so boats dirt bikes and people who need to go real fast with minimum weight use two stroke. The power potential for the same displacement in a naturally aspirated engine goes to the two stroke. They pollute more and have to be rebuilt more often. No one solution is perfect for everyone, thats why there both options. I still miss the 500 cc superbikes in moto gp

[obryan214]

my 4 stroke Yamaha 25hp gets about twice the mileage of my 20hp Suzuki without the expensive mix and all the lovely smoke and is much quieter. it only weighs about 30 pounds more which is its only drawback for me.

[Idstud]

There have been a lot of good points made in this thread. For me I would have to go with a 4 stroke and here are things I have looked at. I do feel they are more fuel efficient. You dont have to worry about the oil injection system failing and loosing your 10,000 + motor. I know they have gotten better over the years but Im a mechanic and things fail. Also look into the places you like to fish there are areas that ban 2 strokes and some have to meet certain guide lines. I dont want the sheriff to bother me while Im enjoying my day on the water because he has to check and see if I have the right style of 2 stroke. 2 strokes are much louder when running at top speed or even an idle. There even louder if your running a pump. 4 strokes are quieter and idle down nice you can reach slow trolling speeds with a smooth quiet ride. Mixing oil in the gas is a pain and it gels up or brakes down faster than unmixed gas. I would have to agree that Hp is Hp but it all depends what you have at the lower unit. For instance you take a 115 hp power head and at the prop you get 115 hp but when you put a pump on that same power head your pushing 85hp at the lower end.

[hewesfisher]

Mixing oil in the gas is a thing of the past, no new motors work that way, and for that matter, some you CANNOT mix with the fuel (Optimax is one).

When someone shows me their actual, real fuel 4-stroke consumption figures, not guesstimates, like this on a 150hp motor, I might be convinced...



For those who can't read it, that's 6.3 miles per gallon, at 3380rpm and 28.7 miles per hour pushing 3000lbs of Hewescraft with a 150hp CARB certified TWO Stroke. This is normal economy with my Optimax and it will perform this way every time I take it out. Mine is 2-star CARB certified while current models are 3-star CARB certified and have been for a couple years now. A 2 star CARB certified motor, is a 2 star CARB certified motor, 2 or 4 stroke. If the motor meets the same standard one doesn't pollute any more than the other. My annual maintenance is identical to a 4-stroke with one less hassle, I don't have to change oil.

[angry john]

still have to change lower unit oil so no big win, i just never thought is was that big of deal.