Helina
Well-Known Member
Does anybody have the knowledge of volvo 2020b diesel engine fuel consumption liters/hour ?
Grateful for the information.
Grateful for the information.
fuel consumption
- Thread starter Helina
- Start date
fdmarsden
Well-Known Member
I have sent you a PM
andy_wilson
Well-Known Member
My 2002 will be somewhat older and possibly less efficient, though is in good condition.
Duties include pushing a 32 foot Westerly Fulmar, usually at 5.5 Knots (2500 rpm), occasionally flat out 6.5 Knots (3200 rpm).
Periods of motorsailing - 2000 to 2500 rpm.
Periods of charging batteries only - 1500 rpm.
Over 5 seasons the average has been almost unshakable at 1.5 lit. / hour.
Some of the diesel put in the tank is not used for the engine, but burned by the diesel heater, mainly at each end of the season.
Duties include pushing a 32 foot Westerly Fulmar, usually at 5.5 Knots (2500 rpm), occasionally flat out 6.5 Knots (3200 rpm).
Periods of motorsailing - 2000 to 2500 rpm.
Periods of charging batteries only - 1500 rpm.
Over 5 seasons the average has been almost unshakable at 1.5 lit. / hour.
Some of the diesel put in the tank is not used for the engine, but burned by the diesel heater, mainly at each end of the season.
G
Guest
Guest
This is a strange matter - as some time ago - I compiled a list of consumptions given by various posts and mails sent to me ... The data showed that most engines until they were pushed hard and also in the much bigger sizes used similar amounts for similar work ... yep - a 12HP was similar at 1.5 - 2.5 ltrs / hr as a 30HP etc.
I did have the chart listed on my personal web-site for anyone to download ... I think it's still there .... Yep - just checked and still there to download / print etc.
Personal Web-Page
I did have the chart listed on my personal web-site for anyone to download ... I think it's still there .... Yep - just checked and still there to download / print etc.
Personal Web-Page
BrickSailor
Well-Known Member
Just tried to follow your link and come up with a page saying you've exceeded your data transfer limit!
I wish I was that popular /forums/images/graemlins/laugh.gif
I wish I was that popular /forums/images/graemlins/laugh.gif
StugeronSteve
Well-Known Member
Concur.. 1.5 ltrs per hour seems to be our average. Turning the wick up across a windless and boring Lyme Bay has pushed it up to 2 L/h. though.
G
Guest
Guest
give me a e-mail address via PM and I will send it to you .....
Thye data transfer limit on Geocities is low and I do apologise !!
Thye data transfer limit on Geocities is low and I do apologise !!
PCUK
Well-Known Member
As a rough guide a naturally aspirated diesel will produce 20 hp per gallon. With a simple sum this will give you the consumption.
G
Guest
Guest
Re: fuel consumption .... 20hp etc.
Its strange when you look at the table and see what people have experienced with different boat - engine combinations ... I expected to see deep body sail-boats consume more than light fin-keel jobs etc. - but look at the numbers and often it seems not the case.
I hope that anyone who downloads can also pass back to me update information of their own findings - so that table can be valuable to others as time moves on ...
The other surprise was the lack of great increase of fuel use with different size engines as you go up the HP ...
Take for example my 42HP Perkins ... I reckon 2 - 3 litres an hour max ... that's at 1/2 throttle, unless of course I want to push the hammer home ! Now I expected many other boats of similar size to mine with lot smaller engines to have miniscule consumption compared to mine ... not so.
Interesting ....
One point I hoped the table would also provide is a guide to an owner of when his engine was consuming too much and possibly at fault ... a point that was quickly taken on my own to see that apart from a small drip on an injector - I am well inside spec consumption.
Please anyone who wants the table - go get it ... or contact me direct ... I am also still interested in further data ... estimated as well as observed. Manufacturers data / technical yes of course - but bench running is not same really.
Its strange when you look at the table and see what people have experienced with different boat - engine combinations ... I expected to see deep body sail-boats consume more than light fin-keel jobs etc. - but look at the numbers and often it seems not the case.
I hope that anyone who downloads can also pass back to me update information of their own findings - so that table can be valuable to others as time moves on ...
The other surprise was the lack of great increase of fuel use with different size engines as you go up the HP ...
Take for example my 42HP Perkins ... I reckon 2 - 3 litres an hour max ... that's at 1/2 throttle, unless of course I want to push the hammer home ! Now I expected many other boats of similar size to mine with lot smaller engines to have miniscule consumption compared to mine ... not so.
Interesting ....
One point I hoped the table would also provide is a guide to an owner of when his engine was consuming too much and possibly at fault ... a point that was quickly taken on my own to see that apart from a small drip on an injector - I am well inside spec consumption.
Please anyone who wants the table - go get it ... or contact me direct ... I am also still interested in further data ... estimated as well as observed. Manufacturers data / technical yes of course - but bench running is not same really.
Phoenix of Hamble
Well-Known Member
[ QUOTE ]
As a rough guide a naturally aspirated diesel will produce 20 hp per gallon. With a simple sum this will give you the consumption.
[/ QUOTE ]Oh good.... does that mean that if I get a bigger fuel tank, my engine will be more powerful? /forums/images/graemlins/wink.gif
Seriously, don't understand that comment?
As a rough guide a naturally aspirated diesel will produce 20 hp per gallon. With a simple sum this will give you the consumption.
[/ QUOTE ]Oh good.... does that mean that if I get a bigger fuel tank, my engine will be more powerful? /forums/images/graemlins/wink.gif
Seriously, don't understand that comment?
fdmarsden
Well-Known Member
A variable which must be eliminated when discussing fuel consumption is engine speed.
A typical prop will absorb power to somewhere near the cube of the rpm.
Assuming a constant specific fuel consumption for simplicity, this means that doubling engine speed will increase fuel consumption by a factor iro eight.
For my 26 ft boat with 14hp diesel, this translates to approximatly doubling the consumption for every 250 rpm increase from the usual 1800/1900 rpm I usually use.
A typical prop will absorb power to somewhere near the cube of the rpm.
Assuming a constant specific fuel consumption for simplicity, this means that doubling engine speed will increase fuel consumption by a factor iro eight.
For my 26 ft boat with 14hp diesel, this translates to approximatly doubling the consumption for every 250 rpm increase from the usual 1800/1900 rpm I usually use.
alb40
Well-Known Member
I think the point is an engine will burn 1 gallon per hour for every 20 horses it produces. So 20hp engine, 1 gph, 100hp engine, 5gph etc.
G
Guest
Guest
Re: fuel consumption .... 20 hp per gall etc....
So lets try the maths ...
My engine is 42 HP .... say as its old ... probably about 35Hp now in reality.
I use average 1/3 - 1/2 throttle ... so for ease of maths lets say throttle is linear to HP - we know it isn't ... but let's make life easy.
So 35 / 2 = 17.5 HP average ...
1 gall ~ 4.5 ltrs
So 20 HP = 4.5 ltrs per hr.
My engine running at 17.5 HP therefore should be using 4.5/20 x 17.5 ltrs ?
= 3.9 ltrs per hour.
This seems grossly too high against my tank useage.
But of course the maths is purely hypothetical and approximated to try and make easy ... so maybe 20 Hp per Gallon is true ???
So lets try the maths ...
My engine is 42 HP .... say as its old ... probably about 35Hp now in reality.
I use average 1/3 - 1/2 throttle ... so for ease of maths lets say throttle is linear to HP - we know it isn't ... but let's make life easy.
So 35 / 2 = 17.5 HP average ...
1 gall ~ 4.5 ltrs
So 20 HP = 4.5 ltrs per hr.
My engine running at 17.5 HP therefore should be using 4.5/20 x 17.5 ltrs ?
= 3.9 ltrs per hour.
This seems grossly too high against my tank useage.
But of course the maths is purely hypothetical and approximated to try and make easy ... so maybe 20 Hp per Gallon is true ???
Evadne
Well-Known Member
Re: fuel consumption .... 20hp etc.
Hi Nigel,
out of interest I just ran your figures through a rough interpolation (using Matlab in case anyone's interested in the gory details) and if I exclude the 135hp entry, which is the only one of that order of magnitude and biases the reults unfairly I get this:
which gives you a surprisingly consistently average figure of consumption in litres/hour = h.p. divided by 14. h.p./14=litres per hour is the same as h.p.x0.127=pints per hour.
This, satisfyingly, almost goes through (0,0), which makes it fairly believable, and I would have said that there are enough points on the graph to at least start to average out the random errors alluded to in previous posts. Compared to my own figures (at the bottom end of the graph) I'd say it's a bit low, but not so far out as to be dismissed.
Dave
Hi Nigel,
out of interest I just ran your figures through a rough interpolation (using Matlab in case anyone's interested in the gory details) and if I exclude the 135hp entry, which is the only one of that order of magnitude and biases the reults unfairly I get this:
which gives you a surprisingly consistently average figure of consumption in litres/hour = h.p. divided by 14. h.p./14=litres per hour is the same as h.p.x0.127=pints per hour.
This, satisfyingly, almost goes through (0,0), which makes it fairly believable, and I would have said that there are enough points on the graph to at least start to average out the random errors alluded to in previous posts. Compared to my own figures (at the bottom end of the graph) I'd say it's a bit low, but not so far out as to be dismissed.
Dave
fdmarsden
Well-Known Member
Re: fuel consumption .... 20 hp per gall etc....
Look up Kubota website, this shows that a 30+hp engine will use at best 0.41 lbs per hphour.
This gives 8.2 lbs for 20 hphours, which is just about a gallon.
The gallon per 20hphours is a good figure, therefore, so your maths are ok, on that basis.
Look up Kubota website, this shows that a 30+hp engine will use at best 0.41 lbs per hphour.
This gives 8.2 lbs for 20 hphours, which is just about a gallon.
The gallon per 20hphours is a good figure, therefore, so your maths are ok, on that basis.
Helina
Well-Known Member
Re: fuel consumption .... 20 hp per gall etc....
Thank you all for excellent information ! In my boat, a 40' Outremer catamaran I have two engines and when the hulls are quite narrow and I propably use the engines when relatively calm, as conclusion maybe 1,5 l/h / engine is very near the truth. At the end of next week I'll start my Atlantic crossing and when having fuel 700 l and the rest is maths...
Thank you all for excellent information ! In my boat, a 40' Outremer catamaran I have two engines and when the hulls are quite narrow and I propably use the engines when relatively calm, as conclusion maybe 1,5 l/h / engine is very near the truth. At the end of next week I'll start my Atlantic crossing and when having fuel 700 l and the rest is maths...
fdmarsden
Well-Known Member
Re: fuel consumption .... 20 hp per gall etc....
Except..............
That your engine develops maximum power at, or close to, max rpm
At 1/3 throttle the prop cannot absorb that much power.
As in my other post, at half speed, dependent on the prop matching, it will be using something like one eigth of max power, so your 45 hp engine will be producing 5 bhp or so and the consumption will therefore be in the region of one and a half litres/hour
Except..............
That your engine develops maximum power at, or close to, max rpm
At 1/3 throttle the prop cannot absorb that much power.
As in my other post, at half speed, dependent on the prop matching, it will be using something like one eigth of max power, so your 45 hp engine will be producing 5 bhp or so and the consumption will therefore be in the region of one and a half litres/hour
alex_rogers
Well-Known Member
Why all the secrecy?
fdmarsden
Well-Known Member
???
Rick
Well-Known Member
Re: fuel consumption .... 20 hp per gall etc....
My D850 Kubota is supposed to be 22 hp at 3,000 rpm - at 2,700 rpm, I use 2.1 litres per hour.
My D850 Kubota is supposed to be 22 hp at 3,000 rpm - at 2,700 rpm, I use 2.1 litres per hour.
