fuel savings 250 h.p. 4-stroke vs. carbureted engine

[9100]

Can anyone give me best guess on expected fuel savings on switching out a 250 h.p. carbureted engine for a 250 h.p. 4-stroke?

[mjkten]

Should double mileage. Going to a modern high pressure two stroke would do the same. In this case, newer is better.

[A Few Dollars]

A carb 2 stroke - at least 30%

[CSoul]

45% plus no 2 stroke oil to buy and no carbs to clean.

[SCAngler]

CSoul - 5/9/2008 6:49 AM

45% plus no 2 stroke oil to buy and no carbs to clean.

25 to 35 % is what you will save. the 2 stroke oil & the oil changes for the 4 stroker will cancel each other out. the no carbs to clean is right on along with quieter opperation & almost no smoke. The only negative is if you are buying a new engine for better fuel economy the numbers will never work. the new engine will never save you enough gas to offset the cost . If you want the new engine then buy it
good luck

[Sleeper]

SCAngler - 5/9/2008 4:30 PM

The only negative is if you are buying a new engine for better fuel economy the numbers will never work. the new engine will never save you enough gas to offset the cost

The current cost of fuel has changed things a bit of course the hours per year are critical to the "justification" cost wise.

As an example I will use a Regulator 23 test with a F250 where cruise will burn 9.2 gph. A carb 250 would burn 30% more (a conservative number IMO) which make for 12 gph thus a 2.8 gph increase.

Gas Pump price of $2.60 ($7.28 an hour)
Marina price of $4.00 ($11.20 an hour)

Use Ed's marine price of $15,000 for a F250 and it would take 2000 hours to break even at gas station prices but only 1330 hours at current marina prices BUT assume you run the engine for 3 years at your average hours and then sell the boat, how much more is it worth with a 3 year old F250 than your current carb engine that will have absolutely zero value in three more years?

I did that math so you can give it to the Admiral and get immediate approval. Just simply tell her the new engine will save over $11.00 an hour.

[thomas70]

We repowered a comercial crabber boat last spring, took off a 2 year old 225 Merc Opti and hung a 225 Suzuki. He put almost 900hrs on it last year and this is what he tells me. He went from burning 28 gls a day to 17, we change the oil for him 10 times and he figures he is way ahead of what he was spending in 2 stroke oil. Also he said before he was replacing the lower on the Opti every year from shifting so much. He's on his second season with no issues.

[Sleeper]

thomas70 - 5/9/2008 8:33 PM

We repowered a comercial crabber boat last spring, took off a 2 year old 225 Merc Opti and hung a 225 Suzuki. He put almost 900hrs on it last year and this is what he tells me. He went from burning 28 gls a day to 17, we change the oil for him 10 times and he figures he is way ahead of what he was spending in 2 stroke oil. Also he said before he was replacing the lower on the Opti every year from shifting so much. He's on his second season with no issues.

uh oh, you just brought the efficiency of the Optimax into question. Stand-by the DFI crowd is coming......

[kerno]

Sleeper - 5/9/2008 3:30 PM


Gas Pump price of $2.60 ($7.28 an hour)
Marina price of $4.00 ($11.20 an hour)

$2.60? Where? Regular at the gas stations in the People's Republic of California is currently 3.92 per gallon.

[thomas70]

I'm not bashing opti's thats just what was on the boat. And the guy that runs the boat keeps very good records, so he knows what he spends and makes on the boat.

[bms1939]

I think he meant $3.60/ gallon.

[dingbat]

Sleeper - 5/9/2008 5:30 PM

Use Ed's marine price of $15,000 for a F250 and it would take 2000 hours to break even at gas station prices but only 1330 hours at current marina prices BUT assume you run the engine for 3 years at your average hours and then sell the boat, how much more is it worth with a 3 year old F250 than your current carb engine that will have absolutely zero value in three more years?

Even if the carbed motor is worth nothing in 3 years you have spent nothing so nothing is lost. On the other hand the depreciation of the F250 would most likely put you upside down in 3 years.

[bayrunner16]

come to northern ca...4.10 regular at the pump

[Sleeper]

Yes I meant $3.60 so the math is off too. No really my local gas stationis still $2.60 a gallon, for washer fluid.

[Sleeper]

dingbat - 5/9/2008 9:19 PM

Even if the carbed motor is worth nothing in 3 years you have spent nothing so nothing is lost. On the other hand the depreciation of the F250 would most likely put you upside down in 3 years.

That statement is so flawed it is funny. Have you seen how the boats with carb OBs are selling these days? I am guessing you own one and know.

[A Few Dollars]

dingbat - 5/9/2008 5:19 PM
Even if the carbed motor is worth nothing in 3 years you have spent nothing so nothing is lost. On the other hand the depreciation of the F250 would most likely put you upside down in 3 years.

Probabally at least a $10,000 - $12,000 difference to trade your motor and upgrade. That buys a lot of gas.

[SCAngler]

Most boaters only put 30 to 50 hrs a year on their engines. You may extend that to 75 to 100 hrs a year in the warmer climates.
Taking the most liberal estimate means it's going to take you 13 years to.get 1300 hrs on an engine.
If your putting 900 hrs a year on an engine you are putting more hours a year than most guides fishing full time for a living.
For the avg. Boater the numbers even at the higher gas prices still do not work out.
The dfi engines get similar fuel numbers to the four stroke.

[Sleeper]

A Few Dollars - 5/9/2008 10:00 PM

Probabally at least a $10,000 - $12,000 difference to trade your motor and upgrade. That buys a lot of gas.

I must look at this issue different than most. My first "justification" starts with the future value of the boat with the newer engine. If you figure a new F250 at even 15K today, what do you get back for it when you sell your boat in 3 years? Let's for fun assume you only get back 10K. I think you would agree that if you were looking for a used Contender, Regulator etc and were down to two identical boats one with an old Yammie 250 carb and one with a 3 year old F250 with 400 hours the 4 stroke boat is worth around 10K more.

That means that your true cost of the new engine was 5K. Then figure the fuel savings at cruise rpms in addition which is right around $12-13 per hour at today's prices. If you run about 400 hours in those 3 years you have broken even.

The benefit of ownership over that period has many other advantages perhaps the most significant one being you just ran an engine 100% under mfg warranty and incurred zero repair bills.

The point is you cannot discount the future value of the new engine. When it is sold and gone in 3 years you did not pay 15K for it, because you get back a good part of that investment. The usage hours per year and the future value of the boat with the new motor are all arguable numbers but the fact remains that you don't "invest" 15K for a new engine and get zero for it after three years and 400 hours. The future value must be in the equation according to Accounting 101. I also don't think gas is going to get any cheaper. My local marina now has regular at $4.65 so for a water kept boat the increased cost per operating hour between these engines is closer to $13-14 per hour.

[stapon251]

I get 30 % better economy with a Yamaha 200 efi at cruise than the old carb. Dfi and 4 stroke are about 10% better yet from friends rides. Way better at troll. At least double.
The old pig will not be worth much on resale. Some would say runner till shes done in 2 to 3 years, and repower then.

[Pursuit2470]

I used Sleeper's logic to talk myself into upgrading from a 6 y/o Yam 250 OX66 with 650 hours.......to a Suzuki 300 4S with a 6 year warranty..........additional reasons......I do go offshore a few times a year with a single.........reliability.......I talked my self out of trading up to a 28-30 with twins.......so I tell myself I saved money there..........but the facts seem to be.......a 60% fuel savings at troll........35-40% at cruise........no smoke.....no vibration.........and maybe some peace of mind.....50 miles off the beach?