outboard fuel economy spread?

Bigtalljv · 08 February 2013, 22:29

Hi,

I'm curious what the fuel economy spread might be for newer outboard engines, engines less than 5 years old. Bigger ones, 250hp or so.

I read a lot about some engines getting better economy but I'm not quite getting how big the difference might be? The best engines might get 10% 50% 100% better economy that the worst engines?

Let's try not to get into a outboard slander-fest, I know there are many strong feeling in this department.

Thanks,
Jason

ppenman · 08 February 2013, 22:46

Quote:

Originally Posted by Bigtalljv

Hi,

I'm curious what the fuel economy spread might be for newer outboard engines, engines less than 5 years old. Bigger ones, 250hp or so.

I read a lot about some engines getting better economy but I'm not quite getting how big the difference might be? The best engines might get 10% 50% 100% better economy that the worst engines?

Let's try not to get into a outboard slander-fest, I know there are many strong feeling in this department.

Thanks,
Jason

Hi Jason,

What are you actually asking here? Are you asking for people to give you their consumption figures for a particular engine model so you can perform some analysis. I can tell you what my engine boat combo gives but I don't know how it would perform with a different engine.

jezza2011 · 08 February 2013, 22:51

they all do 1ltr per mile lol.

ppenman · 08 February 2013, 22:52

Quote:

Originally Posted by jezza2011

they all do 1ltr per mile lol.

If only. I dream of 1 Ltd a mile.

jezza2011 · 08 February 2013, 22:54

oh man...

ppenman · 08 February 2013, 22:57

Quote:

Originally Posted by jezza2011

oh man...

Hmm. This is quite sad. I'm sure when I was younger my dreams were far more exciting.

jezza2011 · 08 February 2013, 23:00

I dont dream. strange. i uesd to but dont anymore..... :-)

ncp · 09 February 2013, 00:19

Jason, you'll have to look it up on each manufacturers website. They'll probably give you burn number in gallons per hour at XXX rpm. Now, what XXX rpm translates into XXX speed is going to be unique to your hull. Everyone can take guesses but, I'd guess you'll be looking a fuel economy (and I use that term loosely) of just over 2 miles the gallon.

I've seen the fuel management readouts on a friends Hurricane w/ twin Yamaha 150hp HPDI's at 2.1 mpg at cruise. You'll be running a single so you'll have less drag and get a little better than that I'd wager.

If you'd gone diesel, I've estimated that I get 4.4 mpg @ 2000 rpm @ 26 mph and 3 mpg @ 2700 rpm @ 36 mph.

Bigtalljv · 09 February 2013, 03:52

Everybody says certain engines are easier on fuel than other. To what degree is the fuel economy better between engines? If I buy one engine over another will one get twice the fuel economy? 10% better ?

Yes talking single gas outboards. People rave about fuel economy of certain engines but from what I can see the spread is only about 10% between the various brands.

Jason

Pikey Dave · 09 February 2013, 04:02

Very very difficult to quantify. So many variables, hull, prop, gearbox, driving style, windage. If I was to make a semi educated guess, I'd say there's not much in it if you are comparing modern DI engines of any flavour.

Bigtalljv · 11 February 2013, 23:53

Is any one outboard inherently more economical than another? that's what I should have asked first.

I want to take the hull out of the equation. I don't care what hull, I want the engine tests to be on the same hull, don't care what. Any boat, any hull, if you take two of them and try the different engines on the two what kind of variation might you see?

The makers tech bulletins are great but what I want is for them to use the same boats so we can eliminate the hull from the equation.

It would be safe to narrow it down to 4 strokes.

How crazy do I have to get deciding what engine I get?

Jason

9D280 · 12 February 2013, 09:01

Problem is you can't take the hull out the equation!

With boats there are so many variables (e.g I bought a used engine for my Rib, and after one trip I needed to up the prop pitch by 3" to stop the engine killing itself by over revving - it was pushing a small cabin cruiser along in it's previous life. - The "unmeasurable" factror in this was the previous engine was a long stroke 2 Cyl of almost equal horsepower. Sounded great when you opened the throttle & let it sing at WOT, but after a couple of hours of cruise downing speed by 4 knots & running it at 3/4 throttle was a lot less grating on the eardrums. the "new" 3 Cyl goes "quiet" at not far off WOT, so I tend to crusie now around 1000 rpm higher than the old machine....

There really are a LOT of factors in real world fuel economy.

The only "general" one you can safely say is that a modern 4 - stroke will drink less than an oldschool 2- stroke IF you do a LOT of low speed / close to idle throttle boating.

FWIW I get 0.83L / Nautical mile out of a 30YO boat and a 25YO engine (0.96 Statute miles - yep, 1L/mile as a round number!

)

Dan Gurney · 12 February 2013, 09:42

Quote:

Originally Posted by 9D280

Problem is you can't take the hull out the equation!

I think what the OP wants is for someone to take the all the 250hp outboards from the various manufacturers over the past 5 years or so and stick them, one by one, on the back of the same hull, run it for a bit at different speeds etc, and then tell him whether the most fuel efficient one is more than 10% more efficient than the least efficient one, and roughly what the spread is.

Given that no-one is going to actually perform this experiment the next best thing is for someone with experience of a wide variety of engines (i.e. not me) to give their opinion on whether the spread is likely to be greater than 10%.

Sorry if I have misinterpreted you Jason....

alystra · 12 February 2013, 11:28

This subject comes up on here every now and again. I seem to remember someone posting a list of engines with stats, including fuel consumption figures, which came from a test done somewhere in Scandinavia (I think).

I think it was re posted in a similar thread not too long ago. Of course, I can't remember when or where, but it does exist.

If you have a lot of time, maybe the search function will find it for you?

PS Last year I got 1.56 nautical miles per litre. 5.3m RIB Honda 90. Cruising speed 23-25 knots.

jambo · 12 February 2013, 13:24

Quote:

Originally Posted by alystra

This subject comes up on here every now and again. I seem to remember someone posting a list of engines with stats, including fuel consumption figures, which came from a test done somewhere in Scandinavia (I think).

I think it was re posted in a similar thread not too long ago. Of course, I can't remember when or where, but it does exist.

If you have a lot of time, maybe the search function will find it for you?

PS Last year I got 1.56 nautical miles per litre. 5.3m RIB Honda 90. Cruising speed 23-25 knots.

Ah you West coast boys know how to squeeze the last drop!!

Sent from my iPhone using Rib.net

Bigtalljv · 12 February 2013, 14:49

Yes, Clamchowder hit it right on the head.

We have the third highest gas prices here in CA, which I think are the highest un the US, so yes, squeeze everything I can. Now I know that is still nothing compared to the price in the rest of the world.

I did a search but it's kind of an ambiguous topic and I didn't run across it. I got lots of results.

Jason

alystra · 12 February 2013, 15:12

Quote:

Originally Posted by jambo

Ah you West coast boys know how to squeeze the last drop!!

Sent from my iPhone using Rib.net

Put it through twice mate.

I was initially disappointed with the consumption (1.3mpl) of the new Honda - my old carbed Mercury 90 managed 1.6 mpl - but now the engine is loosening up it's doing much better. Really smooth and quiet now too. With a bit of luck it may get even better this year.

Cheers, Tony.

captnjack · 12 February 2013, 15:24

Quote:

Originally Posted by Bigtalljv

Yes, Clamchowder hit it right on the head.

We have the third highest gas prices here in CA, which I think are the highest un the US, so yes, squeeze everything I can. Now I know that is still nothing compared to the price in the rest of the world.

I did a search but it's kind of an ambiguous topic and I didn't run across it. I got lots of results.

Jason

I know this was a serious question, but sounds like you can't afford a boat in the first place... Or go less than WOT. Or get a smaller less powerful boat.

If you got the money for a 250hp you should NOT be whining about fuel costs. If you are, get a 175hp...

Pikey Dave · 12 February 2013, 15:43

Quote:

Originally Posted by Bigtalljv

Yes, Clamchowder hit it right on the head.

We have the third highest gas prices here in CA, which I think are the highest un the US, so yes, squeeze everything I can

Well BooHoo

Try paying £6 quid a gallon (around $9.50) admittedly that's for a proper gallon, not one of your piddly little US ones

kerny · 12 February 2013, 15:53

Quote:

Originally Posted by Pikey Dave

Well BooHoo

Try paying £6 quid a gallon (around $9.50) admittedly that's for a proper gallon, not one of your piddly little US ones

Aye!! the US gallon is 2 pints short...I don't know how the Yanks put up with that