News:

Welcome to the largest gathering of ARIMA boat owners anywhere. We are a forum based gathering of Arima Boat enthusiasts that like to pleasure cruise, fish, camp, and hunt. While Arimas are centered in the PNW, we have members across the globe. It is 3/4's water after all. Lurk, join up, and post about your Arima upgrades, family trips, and of course, your fishing exploits. Just remember to add photos whenever possible.

Main Menu

2 Stroke Vs 4 Stroke Fuel Burn

Started by mariner, February 27, 2018, 01:41:59 PM

Previous topic - Next topic

0 Members and 1 Guest are viewing this topic.

mariner

Hello everyone, Was hoping to get some feedback on fuel burn rates between an older Suzuki DT140 2 stroke EFI engine vs a current generation 115 on a 19 or 21 Sea Ranger at cruising speeds.  I have called Suzuki dealers and Suzuki Marine Corporate office and did not get any info.   I understand strokes are not as fuel efficient, especially Carburated  2 strokes.  However, I am curious to find out anyone who has past experience with going from a 2 stroke(EFI if possible) over to a 4 stroke and what type of fuel economy savings you received.  Obviously going from a 115 2 stroke over to a 150 4 stroke you may not see a difference but I am curious to see what I would expect if I were to go from the 140HP 2 stroke EFI suzuki over to a new 115 Yamaha or Suzuki.   Would I see a difference in fuel burn to the magnitude of 50% less fuel burn on the new 115 compared to the DT140 or would it be more like 25-33% less fuel burn?  Any thoughts or past experience would be appreciated.  Thanks
1999 19 Sea Ranger HT: 2018 Merc115 CT ProXS: 2018 Merc9.9 ProKicker

Threeweight

I would get an idea of your current motors use by filling it up, running it on a trip or two while tracking miles traveled on your GPS, then filling up again and seeing how much fuel is needed to refill the tank.  Then divide your miles traveled by fuel consumed.

Figure out what your boat uses, then compare with the guys here who do track that kind of data (especially the Tuna! crowd, who track fuel burn very closely).  Most guys, and almost all guys with 2 strokes, are not running fuel meters or NMEA 2000 networks w/ engine data.  You are going to get a lot of anecdotal info that isn't very reliable. 

Based on my own experience re-powering my old Sea Chaser, and following threads from a variety of folks who have re-powered, I would give a ballpark estimate of a 25% to 50% improvement in fuel economy with a modern fuel injected motor vs. an older carbed 2 stroke.  DI 2 strokes and simpler 4 strokes will be in the 25% range, newer 4 strokes with lean burn fuel injection and variable cam profiles will be closer to 50%.  On my old 17' Chaser, I went from a 1989 Johnson 90 2 stroke (carbed) that average 3.25 to 3.5 mpg on the Columbia/Willamette Rivers (based on miles traveled divided by fill-up volume), to a 2009 Suzuki DF90a with lean burn fuel injection and variable valve timing that averaged 6.25 to 6.5 mpg @4000-4500 RPM (tracked through the engines computer).

My current boat (a 22' Hewescraft hard top tin can) with a Honda 225 averages about 3.25 used in the same conditions.

However, all of that said... a new motor's fuel savings are probably not going to pencil out economically, unless you put A LOT of hours on your boat every season.  IMO, the main reasons to repower are improved reliability and eliminating the godawful racket of an old 2 stroke.
Former Sea Chaser 17 owner
Defiance 250 Admiral, twin Yamaha 150's and T9.9

"Never turn your back on fear. It should always be in front of you, like a thing that might have to be killed."
       --- Hunter S. Thompson

mariner

Good insight Threeweight...I agree with you on the reasons to repower.  It's a reliable engine so I think I'll use it for the next year or so while in the meantime look for a well taken care of used 115 4 stroke.  Buying a used 4 Stroke seems like a good compromise between better reliability than a 2 stroke while not breaking the bank dishing out money on a new 115.  Just have to make sure I get the engine thoroughly inspected because getting a lemon used 4 stroke can be a bigger headache.
1999 19 Sea Ranger HT: 2018 Merc115 CT ProXS: 2018 Merc9.9 ProKicker

Chief of the Boat

Here is some numbers on their four strokes:
https://yamahaoutboards.com/en-us/home/owner-resources/all/performance-bulletins
http://www.suzukimarine.com/Product%20Lines/Outboard%20Motors/Products/DF140/2012/DF140A.aspx

I have done 20+ sea trial reports on new and re-powered Arimas all with Yamaha and Honda power.   I will share them if anyone would like a copy PM me with your e-mail.   
If you don't have a fuel rate meter on the  DT140 it will be hard to come up with good data, since the NMEA 2000 on the new engines is pretty spot on.
My biggest concern with the older two strokes especially Suzuki's is parts availability. 
:twocents:



Fisherdv

#4
IMO a properly maintained 2-stroke can be just as reliable as any 4-stroke. I ran a 2-stroke HARD for over 20 years and it ran as good at 20+ years later as it did on day one. The main thing to watch for on a carbed 2-stroke is clogged carbs and carbon deposits. If those are kept in check they can be very reliable motors IMO and are much easier for DIY repairs. I did however hate the smoke while trolling
2018 Sea Chaser 16, Honda BFP60

Threeweight

Except you have 20 year old hoses, belts, wiring fuel pump diaphragms, etc...

Then throw ethanol into the mix.  A fueling problem in an engine that relies on it's fuel for lubrication can be catastrophic. 
Former Sea Chaser 17 owner
Defiance 250 Admiral, twin Yamaha 150's and T9.9

"Never turn your back on fear. It should always be in front of you, like a thing that might have to be killed."
       --- Hunter S. Thompson

Fisherdv

Quote from: Threeweight on February 27, 2018, 05:00:42 PM
Except you have 20 year old hoses, belts, wiring fuel pump diaphragms, etc...

Then throw ethanol into the mix.  A fueling problem in an engine that relies on it's fuel for lubrication can be catastrophic. 
Those old hoses, fuel pump, wires all changed per proper maintenance. Even a 20+ year old 4-stroke would need new fuel hoses, wiring etc.
2018 Sea Chaser 16, Honda BFP60

mariner

The DT140 2 stroke is EFI so hopefully a tad better fuel economy that the Carbed versions.  I have a 4 stroke 9.9 so no issues with smoke/fumes while slow trolling. 
1999 19 Sea Ranger HT: 2018 Merc115 CT ProXS: 2018 Merc9.9 ProKicker

Fisherdv

As far as fuel burn what 3Wt said. I would probably never own another 2-stroke motor I was just giving my personal experience for those that have a 2-stroke and need to continue to run it for a few years or more until they can acquire/afford to get a 4-stroke
2018 Sea Chaser 16, Honda BFP60

Omega3

It depends on which 2 stroke you have.I regularly run from Pt.Defiance launch to the mouth of the Nisqually River in late summer.40 mile round trip plus trolling with the kicker for a few hours.I burn 6 to 7 gallons per trip.I go as fast as conditions will allow which usually means close to wide open.From what I see on fuel burn with a same size motor I would burn more fuel with a 4 stroke and lose speed.
05 Sea Ranger 19  05 Evinrude 135 DI   17 Yamaha F8

Threeweight

#10
My bias is pretty well known, but IMO an engine that relies on its fuel for lubrication has an inherent durability disadvantage against a wet sump motor. 

In a 4 stroke, a gummed up fuel system that causes it to run lean means your engine runs like crap but nothing vital is at risk.  An engine that relies on its fuel for lubrication that runs lean is risking a melted piston or worse.  See Haberdashers "Fix or replace?" thread on his Etec a few weeks back.

The flip side is two strokes have an inherent advantage over 4 strokes in weight and torque, which is why you don't see 4 stroke chainsaws or weed whackers.  In outboards, it's a mixed bag.  Do you place more value on weight and acceleration, or on fuel economy and durability?

As far as economy numbers go, it is hard to get reliable data as most of the Arima's with NMEA 2000 networks or fuel flow meters are 4 strokes.  I'd love to see some hard data to compare.  He's a screenshot from my old Arima with the Suzuki cruising at about 4000 RPM, getting about 6.5 mpg.

Former Sea Chaser 17 owner
Defiance 250 Admiral, twin Yamaha 150's and T9.9

"Never turn your back on fear. It should always be in front of you, like a thing that might have to be killed."
       --- Hunter S. Thompson

Omega3

Plenty of 2 strokes built 40 years ago are still running today.The only hard data I need is how much fuel I have when I leave the dock and how much is left when I get back.Plenty of data online about new 2 stroke vs.4 stroke fuel economy.The screenshot you show is why I like 2 strokes.4000 rpm,17 mph?4000 rpm and I am going 34 with close to the same fuel burn.I have seen my share of 4 stroke boats stuck at the dock.
05 Sea Ranger 19  05 Evinrude 135 DI   17 Yamaha F8

Threeweight

Lots of guys love their two strokes, and the technology has some clear advantages.  I have been around 2 stroke engines my entire life, from outboards to the Kawasaki and Honda dirt bikes my brother and I raced as kids, and I have some strong opinions about em'  :stirthepot:

Your RPM's at speed, and top speed, is a function of how you choose to prop your motor. 

I ran a 4 blade, 15 pitch by 13 3/4 diameter aluminum prop on the 17' Chaser, for carrying a heavy load and acceleration for bar crossings.  It gave me a comfortable cruise of 18-22 mph or so, and a top speed of about 32.  A 17' Arima will pound your fillings out going much faster than 22 on the ocean off the Oregon coast.  I got closer to 7 mpg with a 3 blade 16 pitch, 14" diameter stainless, with a top speed of about 34, but gave up some low speed acceleration. 

36 mph is about as fast as a 17' Arima hull can go, pushed by a 115 hp motor.  The wide hull is great for stability and low speed planing, but not so great for top speed.  The extra 2' of length makes a big difference in potential speed for a 19', and the step up to 21' is greater still. 

As a reference point, my tin can with a Honda 225 is capable of 50+ mph with 19 pitch, 15.5" diameter 3 blade Honda stainless prop.  I prefer to prop it with a 15 pitch, 14.5" diameter 4 blade Solas Titan, which limits my top speed to about 45 mph and gives up some fuel economy, but handles heavy loads vastly better. 
Former Sea Chaser 17 owner
Defiance 250 Admiral, twin Yamaha 150's and T9.9

"Never turn your back on fear. It should always be in front of you, like a thing that might have to be killed."
       --- Hunter S. Thompson

amazing grace

i have said many a time that I like two stroke outboards. I had a 96' Yamaha V4 115hp on my 89' 19SR and it was a great motor. The power to weight ratio was fantastic. I felt like that motor was made for that boat. It was light, nimble and powerful. Probably the best combo I have ever had.
Fuel economy was neither great nor terrible. My experience tells me on average a 4stoke vs two stroke of the same hp on the same boat is is going be better than twice on a 4s. More like 2.5x or 3x.
The exception would be a new technology two stroke, ie: Evinrude E-tec.

FWIW, pertaining to this thread.
1989 22' C-Dory Angler

1997 19' Sea Ranger hardtop with Alaskan bulkhead

mustang65fbk

#14
I think it really just depends on the boat as well as the motors being used.  My uncle had a 1993 Bayliner Trophy that was 27' and had twin 175hp 2 stroke Mercury's.  He had the motors gone through, the carbs cleaned, new fuel lines, pumps and everything else yet the motors still burned oil like crazy and they smelled quite badly.  The boat also sucked the fuel dry, especially when at WOT.  I'd have to imagine that a single or even twin 4 strokes would've done much better on fuel economy than those engines.  Obviously it's an apples to oranges comparison as that's the only boat that I have to compare my Arima to but I'd pick a 4 stroke over older 2 strokes any day of the week.  It also obviously depends on maintenance and the amount of hours on the engines.  His boat had a 190 gallon fuel tank and the engines had over 1500 hours on them.  The thing would suck fuel like crazy and the gas bill was quite expensive.  The engines were also quite heavy, especially having twins, and a 190 gallon fuel tank sitting at the rear of the boat just added even more weight to the boat.  Gasoline itself weighs 6.3lbs/gallon and at 190 gallons you've got 1200lbs on the back end, just for fuel.  Each engine was probably another 350-400lbs each, so lets say 2000lbs total for the engines and full tank of fuel.  Then you add passengers, fishing gear and everything else.  The boat was still pretty quick for being over 8000lbs as it would do 45mph but the amount of fuel savings with a smaller, more efficient 4 stroke is just insane.  A 48 gallon fuel tank on my boat weighing around 2500lbs that only goes a max of 35mph is much easier on the bank account than a 200 gallon fuel tank on an 8000lb boat that can go 45mph.

Now my parents did have an older 1989 17' SC with a 90hp Yamaha 2 stroke and that thing ran quite well and didn't burn up too much fuel.  That being said we would really only use it to check the crab pots and didn't do much fishing in it as the fishing wasn't very good when we had it.  We only filled that boat up once or twice a summer, but then like I said we mainly just used it for crabbing, fishing every so often and weren't out there fishing for 5-6 hours a day.  Also, it's half the weight of my 21' SR S, so it'll likely use less fuel to begin with.  The issue I had with that motor was that we would always winterize it with Stabil, clean it up with the pressure washer and so on, yet the next year we would have to have the carbs cleaned, fixed or so on as they had gotten gummed up over the winter.  The 4 strokes seem to *knock on wood* have better luck with winterizing them.  I also like the fact that 4 strokes have less fumes and are considerably quieter than a good deal of 2 strokes, except the modern E-tec's.  I remember when I first bought my boat and was taking it for a spin on Lake Stevens on it's maiden voyage and wanted to see what she was made of.  Got her up to almost wide open throttle and then wanted to see how quickly she could stop.  So I slowed her way down, almost to idle and couldn't hear the motor.  I thought the motor shut off or had died on me, but she was still peeing and it was just so much quieter that you couldn't hardly hear it running.  Of course like I said, I'm used to my uncles old boat and running twin two strokes that are much louder but I'm sold on the 4's.
2003 21' Sea Ranger Skip Top
2003 Honda 130hp 4 Stroke

StreamFixer

I found both fuels burn about the same when starting my brush pile...  2 stroke fuel maybe a bit smokier...  :stirthepot:

StreamFixer
'01 Hewes Sportsman 18
'14 Yamaha 90
'01 T8 w/ solas 4 blade
'19 Minn Kota 80# (Alterra)
'97 19SC w/ Salt Boss Top


"By the grace of God we travel upon the rivers and sea..
They, like He, are mightier than me."  Mike Jesperson aka 'Nalu

amazing grace

 Russ, i don't think you are really paying attention. The two stroke mix will burn much slower and there for longer and better mileage.

The regular gas will burn faster and hotter and there the mileage is not as good.

Considering the aforementioned burn pile application anyways.  :yeahthat:
1989 22' C-Dory Angler

1997 19' Sea Ranger hardtop with Alaskan bulkhead

StreamFixer

Yeah, you are probably right.  I douse the pile, toss a flare and go get more brush.  Don't really pay that much attention unless it goes out...  Then I have to wait until next day    :hoboy:

StreamFixer
'01 Hewes Sportsman 18
'14 Yamaha 90
'01 T8 w/ solas 4 blade
'19 Minn Kota 80# (Alterra)
'97 19SC w/ Salt Boss Top


"By the grace of God we travel upon the rivers and sea..
They, like He, are mightier than me."  Mike Jesperson aka 'Nalu

jamaica

Quote from: StreamFixer on March 02, 2018, 04:19:23 PM
I found both fuels burn about the same when starting my brush pile...  2 stroke fuel maybe a bit smokier...  :stirthepot:

StreamFixer
I use paint thinner, it's how I get rid of the used stuff if I have some. It doesn't burn off as quickly and you can light it with a match and keep your hair.
1994 19' Sea Ranger 150hp Merc 2stk 9.9hp Yam

Yachter Yat

#19
   I was in grade school with a kid who once threw gasoline on a fire to keep it going.  I don't want to say too much...........but, let's just say...........if you were sitting across from him in the cafeteria..............   We all know better, right?

Yat
History is not the past; it's the present, as we all carry it with us......James Baldwin    
16 SC/Honda 60  (sold)

StreamFixer

your eyebrows grew back didn't they???  Mine did   :bigshock:

StreamFixer
'01 Hewes Sportsman 18
'14 Yamaha 90
'01 T8 w/ solas 4 blade
'19 Minn Kota 80# (Alterra)
'97 19SC w/ Salt Boss Top


"By the grace of God we travel upon the rivers and sea..
They, like He, are mightier than me."  Mike Jesperson aka 'Nalu