Hi, y'all...


Back on the boat and about to pull the shaft and tranny to true the
shaft and plates and, perhaps, redo the MaxProp settings.

However, before I can do the calculations, though I have the pdf of
both the parts and manuals, I can't find anything about the power
curve.

Does anyone have them/know what they are, and willing to share?

Thanks.

L8R

Skip, on the boat for the duration, very small breaks excluded

Morgan 461 #2
SV Flying Pig KI4MPC
http://tinyurl.com/384p2 The vessel as Tehamana, as we bought her

"Believe me, my young friend, there is *nothing*-absolutely
nothing-half so
much worth doing as simply messing, messing-about-in-boats; messing
about in
boats-or *with* boats.
In or out of 'em, it doesn't matter. Nothing seems really to matter,
that's
the charm of it.
Whether you get away, or whether you don't; whether you arrive at your
destination or whether you reach somewhere else, or whether you never
get
anywhere at all, you're always busy, and you never do anything in
particular; and when you've done it there's always something else to
do, and
you can do it if you like, but you'd much better not."

I've got it - anyone else needing it, drop me a line and I'll send it
to you...

L8R

Skip

Skip,
As an engine professional for many decades I can tell you that all you
need is the two published numbers I hope are in the engines
specifications.
That would be the torque peak and speed and the horsepower peak and speed.
For a naturally aspirated diesel this is very close to what a dyno test
would give you.
Turn the HP back into torque (rev*tor/5252=hp)_ and plot it out as two
straight lines (it isn't, but it won't matter much). If I can find it
and you are interested, I could try to post the one page explaination of
this.
Ta Da - power curve

Matt Colie - still trying to get out of Detroit and back to tidal water
after 30+ years.


Skip Gundlach wrote:
Hi, y'all...


Back on the boat and about to pull the shaft and tranny to true the
shaft and plates and, perhaps, redo the MaxProp settings.

However, before I can do the calculations, though I have the pdf of
both the parts and manuals, I can't find anything about the power
curve.

Does anyone have them/know what they are, and willing to share?

Thanks.

L8R

Skip, on the boat for the duration, very small breaks excluded

Morgan 461 #2
SV Flying Pig KI4MPC
http://tinyurl.com/384p2 The vessel as Tehamana, as we bought her

"Believe me, my young friend, there is *nothing*-absolutely
nothing-half so
much worth doing as simply messing, messing-about-in-boats; messing
about in
boats-or *with* boats.
In or out of 'em, it doesn't matter. Nothing seems really to matter,
that's
the charm of it.
Whether you get away, or whether you don't; whether you arrive at your
destination or whether you reach somewhere else, or whether you never
get
anywhere at all, you're always busy, and you never do anything in
particular; and when you've done it there's always something else to
do, and
you can do it if you like, but you'd much better not."

I appreciate that torque and HP are essentially the same, such that
one curve can be derived from the other. It was a revelation that
this conversion can be derived geometrically! However, is it really
true that given two points you can get the full story? What if the
torque peak and HP peak came close together, say at 2500 rpm; then you
would have little info as to how it behaves at 1200 rpm.

Or, using these curves as an example, the straight line approximation
between the two points may be valid, but it says nothing about what
happens outside this range.
http://www.yanmarmarine.com/products...5_TechData.pdf

I'm not trying to debate, I really want to know how to make use of
these curves.

jeff

Matt Colie wrote:
Skip,
As an engine professional for many decades I can tell you that all you
need is the two published numbers I hope are in the engines specifications.
That would be the torque peak and speed and the horsepower peak and speed.
For a naturally aspirated diesel this is very close to what a dyno test
would give you.
Turn the HP back into torque (rev*tor/5252=hp)_ and plot it out as two
straight lines (it isn't, but it won't matter much). If I can find it
and you are interested, I could try to post the one page explaination of
this.
Ta Da - power curve

Matt Colie - still trying to get out of Detroit and back to tidal water
after 30+ years.

Jeff,
This is a wonderful example - thank you for the link to the Yanmar data.
If you know what the cause is, the results outside th published points
can be very closely approximated.

Let's start by looking at the torque curve only:
First - notice the surpressed zero of the plots.
Second - notice that if you were to plot this data with zero-zero at the
lower left, you would notice the the decline in the torque curve from
2400 to 1800 wa less than 5% and probably changes less than that to 1200.
Third - notice that the torque and power curves from 24-3600 are not
far off linear.

Explanation:

Diesel engines have two factors at work (no carburettor curves to deal
with here).
-First is the fuel delivery as provided by a mechanical injection pump
system. At a given rack (fuel control input - not governor or throttle)
the fuel delivered at each injection is substantially identical
regardless of crankshaft speed.
-Second is a feature of all internal combustion engines called
volumetric efficiency [VE] (this is how much air is pumped through the
engine as a function of the swept volume [aka displacement])

Simple rules: (unfortunately 100% true)
-Fuel is torque unless you run out of air (that starts happening at the
torque peak - cams are usually optimised for speeds more to clients
requirements). Maximum fuel delivery is usually determined by the
mechanical capability of the engine components.
-Air is horsepower. As available air declines because of loss of VE
with increasing crank speed, that effectiveness of combustion is lost to
the point that the engine wiil start to smoke.

Did I lose anybody - speak up - time is short and you are probably not
the only one with a question.

Matt Colie

Jeff wrote:
I appreciate that torque and HP are essentially the same, such that one
curve can be derived from the other. It was a revelation that this
conversion can be derived geometrically! However, is it really true
that given two points you can get the full story? What if the torque
peak and HP peak came close together, say at 2500 rpm; then you would
have little info as to how it behaves at 1200 rpm.

Or, using these curves as an example, the straight line approximation
between the two points may be valid, but it says nothing about what
happens outside this range.
http://www.yanmarmarine.com/products...5_TechData.pdf

I'm not trying to debate, I really want to know how to make use of these
curves.

jeff

Matt Colie wrote:

Skip,
As an engine professional for many decades I can tell you that all you
need is the two published numbers I hope are in the engines
specifications.
That would be the torque peak and speed and the horsepower peak and
speed.
For a naturally aspirated diesel this is very close to what a dyno
test would give you.
Turn the HP back into torque (rev*tor/5252=hp)_ and plot it out as two
straight lines (it isn't, but it won't matter much). If I can find it
and you are interested, I could try to post the one page explaination
of this.
Ta Da - power curve

Matt Colie - still trying to get out of Detroit and back to tidal
water after 30+ years.

Matt,

In line with this discussion, maybe you can affirm/clarify a squirmy factoid
from my past (ca 1975). We were simulating the electrical distribution
system for a DDE class of ships and I was told that: when you overload a
gasoline engine, it lugs down, complains, and lets you do something about
it. In contrast, when you overload a diesel (such as the ones that drove
two of the generators) it just quits. (The simulation was to train
operators and condition them to shed the load before the engine quit; among
other things.)

Thanks,
Roger

http://home.insightbb.com/~derbyrm

"Matt Colie" wrote in message
...
Skip,
As an engine professional for many decades I can tell you that all you
need is the two published numbers I hope are in the engines
specifications.
That would be the torque peak and speed and the horsepower peak and speed.
For a naturally aspirated diesel this is very close to what a dyno test
would give you.
Turn the HP back into torque (rev*tor/5252=hp)_ and plot it out as two
straight lines (it isn't, but it won't matter much). If I can find it and
you are interested, I could try to post the one page explaination of this.
Ta Da - power curve

Matt Colie - still trying to get out of Detroit and back to tidal water
after 30+ years.


Skip Gundlach wrote:
Hi, y'all...


Back on the boat and about to pull the shaft and tranny to true the
shaft and plates and, perhaps, redo the MaxProp settings.

However, before I can do the calculations, though I have the pdf of
both the parts and manuals, I can't find anything about the power
curve.

Does anyone have them/know what they are, and willing to share?

Thanks.

L8R

Skip, on the boat for the duration, very small breaks excluded

Morgan 461 #2
SV Flying Pig KI4MPC
http://tinyurl.com/384p2 The vessel as Tehamana, as we bought her

"Believe me, my young friend, there is *nothing*-absolutely
nothing-half so
much worth doing as simply messing, messing-about-in-boats; messing
about in
boats-or *with* boats.
In or out of 'em, it doesn't matter. Nothing seems really to matter,
that's
the charm of it.
Whether you get away, or whether you don't; whether you arrive at your
destination or whether you reach somewhere else, or whether you never
get
anywhere at all, you're always busy, and you never do anything in
particular; and when you've done it there's always something else to
do, and you can do it if you like, but you'd much better not."

Roger,

What you were told is substantially correct. (I would just love to close
there, but it would not be either fair or educational.)

If you just read the post of moments ago, remember that the typical
torque curve of a mechanical fuel pump diesel is flat below the torque
peak (misnomer in much of the diesel community note to follow.)

Most diesels are not quite a flat torque curve because the design had
been optomised one way or the other. They are often so flat that the
overload (as you describe) will cause the engine to keep losing rev
until it the load it is carrying drops or the engine stalls.

BUT - (you just knew that was coming)

The BIG exception here is that the fuel control governor in many truck
engines causes the engine to de-fuel with increasing rev to create what
is called "torque backup" a feature that will allow the truck to slow on
hills with out stalling - this allows a hugh reduction in gear shift
work for the driver.

Promissed note: For many over the road engines designed with torque
backup, the published torque peak is not the actual peak, but the knee
in the torque curve where the governor starts defueling based on speed
to limit the smoke.

Did I say that all well enough so you can ask a question if you have one?

Matt Colie
derbyrm wrote:

Matt,

In line with this discussion, maybe you can affirm/clarify a squirmy factoid
from my past (ca 1975). We were simulating the electrical distribution
system for a DDE class of ships and I was told that: when you overload a
gasoline engine, it lugs down, complains, and lets you do something about
it. In contrast, when you overload a diesel (such as the ones that drove
two of the generators) it just quits. (The simulation was to train
operators and condition them to shed the load before the engine quit; among
other things.)

Thanks,
Roger

http://home.insightbb.com/~derbyrm

"Matt Colie" wrote in message
...

Skip,
As an engine professional for many decades I can tell you that all you
need is the two published numbers I hope are in the engines
specifications.
That would be the torque peak and speed and the horsepower peak and speed.
For a naturally aspirated diesel this is very close to what a dyno test
would give you.
Turn the HP back into torque (rev*tor/5252=hp)_ and plot it out as two
straight lines (it isn't, but it won't matter much). If I can find it and
you are interested, I could try to post the one page explaination of this.
Ta Da - power curve

Matt Colie - still trying to get out of Detroit and back to tidal water
after 30+ years.


Skip Gundlach wrote:

Hi, y'all...


Back on the boat and about to pull the shaft and tranny to true the
shaft and plates and, perhaps, redo the MaxProp settings.

However, before I can do the calculations, though I have the pdf of
both the parts and manuals, I can't find anything about the power
curve.

Does anyone have them/know what they are, and willing to share?

Thanks.

L8R

Skip, on the boat for the duration, very small breaks excluded

Morgan 461 #2
SV Flying Pig KI4MPC
http://tinyurl.com/384p2 The vessel as Tehamana, as we bought her

"Believe me, my young friend, there is *nothing*-absolutely
nothing-half so
much worth doing as simply messing, messing-about-in-boats; messing
about in
boats-or *with* boats.
In or out of 'em, it doesn't matter. Nothing seems really to matter,
that's
the charm of it.
Whether you get away, or whether you don't; whether you arrive at your
destination or whether you reach somewhere else, or whether you never
get
anywhere at all, you're always busy, and you never do anything in
particular; and when you've done it there's always something else to
do, and you can do it if you like, but you'd much better not."