How long do diesel engines "live"?
Cpt. Alex
to twin diesel engines.
I have read some months ago a rule of thumb that a well maintained gas
engine is considered "old", meaning that problems and repairs will start
getting expensive, after 600-700 hours of operation.
Since I am going to buy a 2nd hand boat with twin diesels does anyone know a
similar rule of thumb for diesels?
Thanks in advance,
Alex
Cap1196
life span before being rebuilt. I will say Diesel will run a whole lot longer
then gas.
Also Turbo diesel usually have a shorter span between overhauls compared to
"naturals". Just as an example I had a rare case where I was able to get 8500
hours out of a pair of Detriot Diesel 671TI's
before having them rebuilt.
Thanks,
A.P.
Cpt. Alex
turbo Volvo Penta engines, aged 1990-1992.
Thanks
"Cap1196" <cap...@aol.com> wrote in message
news:20021104172321...@mb-bh.aol.com...
Eisboch
"Cpt. Alex" <alh...@otenet.gr> wrote in message
news:aq6oe5$r1v$1...@usenet.otenet.gr...
Here's what I've been told. In the old days a normally aspirated diesel
(meaning non-turbo) would last longer than you could possibly use it (with
proper maintenance and attention to fuel quality). Probably the best
example are the non-turbo Detroit Diesel 671's. They just don't wear out
and 8000 hours or more is typical before a major overhaul.
The newer, high performance, lightweight turbo diesels do not have the same
track record. Docktalk indicates that it is not really a unique
manufacturer problem, rather that all manufacturers are squeezing more and
more horsepower out of smaller packages, running them at higher RPM and they
just don't have the life expectancy of the old diehards. My dock neighbor
just replaced two 600 (plus) hp Yamars after less than 3000 hours. Another
neighbor replaced one of his Cat 3208's (the V-8 diesel) after about 5000
hours (he is a charter boat operator and takes particular car of the boat
and engines). My Egg Harbor has the 420 hp 3126 turbo diesels and Cat told
me I can expect about 5000 hours before overhaul. Our Navigator has 370 hp
Volvo diesels and I was also told I can expect around 5000 hours before
overhaul.
In any event, the old story of a diesel lasting forever is not true anymore
in my opinion. That said, I will never go back to gas engines for any boat
over 30 feet or so.
Eisboch
JAXAshby
recreational gas engines typically last about 900 hours before needing a major
rebuild, and diesels unsed in the same application last about 1000 hours before
needing same.
on the other hand, most diesel engine owners will tell you that they *know*
diesel engines last gazillions of hours (while sipping 23 milli-liters of fuel
per hour).
Take your pick which you believe, but do remember it's your credit card on the
service writer's desk.
btw, a good rule of thumb as well is that marine recreational diesel engines
will require about $3.50 to $5.00 worth of maintenance per hour used (payable
in clumps at irregular intervals) before a major rebuild is needed.
Jeff Morris
(though he is a bit anti-diesel) - His comments are below. Frankly, I
think a diesel can go a lot longer if its used more - that is, the
wear is a function of years, not hours. I've had several diesel
engines go over 2000 hours and the only serious maintainance is
injector rebuilds - $75 each. One thing that brings the "average
life" down is including high performance diesels - these often need
overhauls after 600 hours.
From Pascoe's site:
http://www.yachtsurvey.com/GasDiesel.htm
The average life expectancy of a marine diesel engine in a
pleasurecraft is somewhere around 1500 hours between major overhauls.
The average boat reaches this in about 8-10 years, meaning that the
average annual operating time averages around 150 hours. If that seems
unrealistically low, consider that that translates into 2-1/2 weeks of
eight hour days. Most boats have years when its even less than that.
If this surprises you, it may surprise you even more when I tell you
that gas engines average around 900 hours before overhauls.
--
-jeff www.sv-loki.com
"The sea was angry that day, my friend. Like an old man trying to send
back soup at the deli."
"JAXAshby" <jaxa...@aol.com> wrote in message
news:20021104183044...@mb-mo.aol.com...
JAXAshby
and even *after* allowing for your extremely exagerated claims, a diesel at
some 3s to 4x to 5x the price is *STILL* a bum deal.
diesels vs gas is discussion for those scared crapless of the sea.
Gould 0738
expectancy is more closely related to the number of gallons of fuel an engine
burns, rather than the number of hours it takes to burn it.
There's some figure floating around, and I don't know what it is, that would
indicate that when an engine has burned 16, 20, or 25 thousand gallons of fuel
it has done all that can be reasonably expected. And this number probably
varies with the individual engine models.
You can get absurd amounts of HP out of
a diesel by just pouring in more fuel and pumping more air through it. The same
displacement blocks have almost unbelievably wide ranges of HP configurations
available.
According to Jax's rule of thumb, ($3.50 to $5.00 per operating hour maintance
cost for a diesel engine), I'm somewhere about $20,000 "behind" on my 1982
Perkins, 165 HP turbo diesel. I think his number is high- he must have a very
expensive thumb.
Here's a very good general rule: The longest lasting diesel engines will
typically be those where the c.i.d is about a 2 to 1 or better ratio to the HP.
My engine has 354 cid and develops 165 HP. Current hours in the high 3k range,
approaching 4 soon. Never rebuilt. Uses very little oil.
I wouldn't be too afraid of the "turbo" concept in and of itself, unless that
turbo is being used to boost the HP way up and beyond the 2 to 1 cid to HP
ratio. A lot of people have had bad experience with turbos on gasoline car
engines, but the dynamics of a diesel boat engine are so much different than a
gas engine in a car that the experience isn't all that relevant.
A lot of builders try to duplicate gas engine
speed performance with diesel engines, and in a broad general sense if you beat
the daylights out of a diesel engine and rev it up like a gas burner, it will
repay you with something more like a typical gas engine's lifespan. Based on
what it costs to replace a diesel, that's a very bad bargain indeed.
JAXAshby
>maintance
>expensive thumb.
No, it's just that I spent nearly three decades selling high end capital
equipment to large corporate businesses, so I am well schooled in the concept
of "Total Cost of Ownership" and how total (as in actual) costs are
determined.
Trust me, dude, it costs $3.50 to $5.00 per hour (costs paid in clumps
irregularly) for parts and maintenance to keep a marine recreational diesel
running long enough to need a major overhaul, even if the owner is blithely
unaware of those costs.
Gould 0738
>irregularly) for parts and maintenance to keep a marine recreational diesel
>running long enough to need a major overhaul, even if the owner is blithely
>unaware of those costs.
Well, your numbers are contrary to my own experience and the experience of many
close associates, but then again we may have all been lucky thus far. I would
consider my own engine "middle aged," and while I've replaced the gear box,
rebuilt the injector pump, rebuilt the injectors, replaced the oil cooler,
replaced the lift pump, etc etc I've not really had to do diddly on the main
portion of the engine itself.
Now of course I do my own basic oil, filter, and zinc changing (more often than
most people), and that does save some $$$.
Our local techs have been known to charge $100 labor to do an oil change
(that's plus parts and oil, naturally), or about $180 for twin engines. That's
at least a buck an hour, if not two, right there.
Wayne B
>Well, your numbers are contrary to my own experience and the experience of many
>close associates, but then again we may have all been lucky thus far. I would
>consider my own engine "middle aged," and while I've replaced the gear box,
>rebuilt the injector pump, rebuilt the injectors, replaced the oil cooler,
>replaced the lift pump, etc etc I've not really had to do diddly on the main
>portion of the engine itself.
>
>Now of course I do my own basic oil, filter, and zinc changing (more often than
>most people), and that does save some $$$.
>Our local techs have been known to charge $100 labor to do an oil change
>(that's plus parts and oil, naturally), or about $180 for twin engines. That's
>at least a buck an hour, if not two, right there.
=========================================
Yep. And what about amortized cost of replacement or major
overhaul? I'm guessing that a major for your Perkins is in the
$10K to $15K range, and replacement at about $20K+. If you
assume 5,000 hours before either required, then that is another
$2.00 to $4.00 per hour. If you then add in things like injector
servicing and other routine maintenance, the price goes higher.
I'm in the unusual and somewhat uncomfortable position of agreeing
that Jax has a valid point here. Say it isn't so!
K. Smith
Am I allowed to chip in?? Diesels can last much longer than petrol motors
particularly "proper" say cat, cummins, GM, Perkins etc
Diesels don't just "happen" to last longer there are good easily understood
reasons.
(i) Diesels are usually better made than similar HP petrol engines, mainly
because they need to be to contain the much higher compression pressures (e.g.
nearly always forged 4 ring pistons vs cast 3 ring or forged steel crankshafts vs
cast iron )
(ii) Another needed difference which has a side benefit of giving longer
service life is a diesel's much longer period of combustion per power stroke. In a
diesel at say idle the injection/combustion starts just before TDC & stops
straight away, but as the throttle is opened the injection pump continues to
inject fuel for a longer period, so the burn can continue even as the piston is
traveling back down the bore (reason diesels are good producers of torque). In a
petrol engine the burn is all but over before the piston much leaves TDC even at
WOT. The outcome is that the diesel piston has the potential to absorb more heat
so the fix is to continuously spray oil up under them to carry that heat away,
this means internal temps are much better controlled than a petrol engine.
(iv) Diesel fuel itself is a reasonable lubricant whereas petrol isn't, end
result is diesels don't suffer as much oil scavenged from the bore as petrol
motors, so last longer.
(v) Until recently diesel engines didn't produce nearly as much HP/ltr as
similar petrol engines. So they were comparatively under stressed, they didn't
need to spin as fast to make a given HP (mostly well below 3000rpm at max) so
could rely upon their inherently good torque production which extended life.
(vi) Diesels are about 10% more efficient that petrol engines so they waste
less heat, most lost heat goes out the exhaust but still plenty goes into the
engine components, mainly the cyl. head, valves etc, so for a given HP a diesel
doesn't tend to locally overheat spots which again extends their life.
(vii) The new trend to light weight high revving high output diesels
particularly in boats is not good news & they can have a very short life. There's
a bit of a scam going on here which I say isn't publicised enough by the dealers ,
boat manufacturers who spruik these things. Most so called "modern" boat diesels
can only put out the claimed HP for a very very short time before the pistons,
head, valves etc become very hot & risk failure regards of how new the engine is.
Two good examples are;
(a) the say up to 285 HP Volvos (based on a 1970s to 80s era Fiat truck
engine!!) which is 3.6 ltrs so has a specific output up at say 79HP/ltr (well
above the latest 5.7 chev & even above the average 4 valve modern petrol engine)
BUT if you read the fine print & to be unkind I say deliberately vague fine print,
you'll find this engine can only make max power for very short bursts at a time!!!
then needs an hour to cool down at much much lower power, so you finish up
cruising much slower than you dreamed in the showroom. About the best this engine
could ever do was about 110 HP in an 80s era Audi car!! suddenly they up the boost
pressure & sell it as well over 280 HP ???
(b) The Yanmar 315 HP engines are a real worry also. Again based on a
Toyota engine not exactly a truck really, but a Landcruiser engine!!. 4.2 ltrs??
not sure can't remember but whatever it's very high output at it's I say
deceptively claimed max power. Again read the fine print you can only make real HP
for the occasional short burst, just to get up on the plane but don't think for a
second you can go skiing because do it too many times in an hour & oops. Again
look at this basic engine in a Landcruiser it's not rated much above 200 HP &
often only 170 HP because they have to account for the bloke who leaves his foot
on the floor towing a big boat up a mountain range, but when it gets rejigged as a
boat motor they up the boost etc so for very short periods they can squeeze the
last ounce out of it, but reliability is probably less than a petrol engine.
(viii) Boats can be very gentle on engines particularly with a fixed pitch
prop, once the engine leaves WOT/max revs the load (torque needed) drops away much
quicker than the revs, so say Chuck's Perkins (6354?) is only making about 28
HP/ltr at WOT/max revs, something they rarely see anyway, also it's a huge engine
physically compared to a 165 HP petrol engine so acts as a giant heat sink
spreading damaging heat away from hot spots. Some of the unturboed Perkins in
pleasure boats seem to last almost forever indeed the injection pump & injectors
are about the only real components that seem to wear out (but they're expensive!),
again clean fuel & filters mean everything.
A good indicator of engine life in a diesel is either how long the fine print
says it can operate at the rated max HP if it's less than say 12-15 mins it's a
highly stressed engine OR better still 40 HP /ltr at max power is a good
conservative output which should give a good compromise over weight, cost, life.
Another major consideration is reliability & safety, obviously petrol engines can
be very dangerous & are never as reliable.
K
UglyDan®©™
guessing that a major for your Perkins is in the $10K to $15K range, and
replacement at about $20K+. If you assume 5,000 hours before either
required, then that is another $2.00 to $4.00 per hour. If you then add
in things like injector servicing and other routine maintenance, the
price goes higher.
I'm in the unusual and somewhat uncomfortable position of agreeing that
Jax has a valid point here. Say it isn't so!
It isn't so!
I've seen my fair share of 6-354 Perkins turbo and naturals run more
than 10000 hrs without a major overhaul, and try more like 7500.00 to
10.000 max for the rebuild. but your prolly right on the replacement
cost. UD
Anjo Sterringa
we service Northern Lights generators and service at certain time
intervals.
Around 10.000 hours a thorough overhaul is called for.
Some people have wrecked their diesel long before that:
- no oil changes /not often enough
- fill / top up coolant with water - the worst is using watermaker
water (which is slightly acid!)
-let the unit overheat, fill it up with seawater
-no maintenance at all, etc.
The cost of maintenance depends on
-the care you take of your diesel yourself
-how big the engine is
-what brand the engine is
(the cost of a RW pump can be very different on different brands)
(so I would not say it's an absolute $ or EUR figure per hour, but
more related to Hp and brand)
My own incredibly old little Volvo MD2 is relatively expensive in
spares, but small so I can still afford it...
It's heavy, but built like a tank, no fancy aluminium parts...
Ciao,
Anjo, Mallorca
email-1
JAXAshby
of their true and actual costs for any project and/or capital gear or plant --
is an involved subject.
For the most part there are soooooooooooooooooooo many actual and true costs
associated that it can be mind-boggling to those not familiar with the process.
Indeed, proponents of particular purchases not thoroughly familar with cost
accounting will often simply deny sometimes upwards of 95% of the costs.
As just a general question, what do you suppose the TCO (Total Cost of
Ownership) is for automobiles on a per mile basis?
hint: for a $25k SUV (you can find lots of them, right?) with a $5K downpayment
(ignored in the TCO calculations made by the AAA, the AAA being an organization
fully dedicated to promoting auto usage), owned three years and driven average
miles the cost is over $0.70 per mile. Leased autos cost more than purchased
(cash or time payments) autos.
If one wishes to believe that no or little maintenance costs are associated
with a marine recreational diesel engine because costs come in irregular
clumps, one is free to do so. But remember, there are more than 100 men making
a full-time living (presumably, a good living) in Ft Lauderdale fixing just
diesel engines in recreational boats (Pascoe's numbers, and he knows the FtL
market).
JAXAshby
>petrol engine the burn is all but over before the piston much leaves TDC even
>at
>WOT.
no. you're describing detonation (not part of a properly running engine) which
blows holes in pistons almost immediately.
> Diesels are about 10% more efficient that petrol engines so they waste
>less heat, most lost heat goes out the exhaust but still plenty goes into the
>engine components, mainly the cyl. head, valves etc, so for a given HP a
>diesel
>doesn't tend to locally overheat spots which again extends their life.
Diesels are typically about 20% more fuel efficient (on a gallon of fuel burned
per hour basis) than a gas engine, but less efficient on a pound of fuel burned
basis.
Also, hp for hp, diesels produce more engine comparment heat. (failing to run
the engine comparment blower on a diesel engine is one of the failure modes of
marine recreational diesels. It's by no means immediate, it most definitely
limits engine life)
SaladinoJA
>From: jaxa...@aol.com (JAXAshby)
>Date: 11/5/2002 7:18 AM Eastern Standard Time
>Message-id: <20021105071824...@mb-fr.aol.com>
>>>Trust me, dude, it costs $3.50 to $5.00 per hour (costs paid in clumps
>>>irregularly) for parts and maintenance to keep a marine recreational diesel
>>>running long enough to need a major overhaul........
Do you have the #'s for a gasoline powered engine?
Gould 0738
>overhaul? I'm guessing that a major for your Perkins is in the
>$10K to $15K range, and replacement at about $20K+. If you
>assume 5,000 hours before either required, then that is another
>$2.00 to $4.00 per hour. If you then add in things like injector
>servicing and other routine maintenance, the price goes higher.
>
>I'm in the unusual and somewhat uncomfortable position of agreeing
>that Jax has a valid point here. Say it isn't so!
Well it isn't, exactly. You're including a theoretical sinking fund for
eventual engine replacement. (The word "sinking fund" should really never ve
used aboard a boat).
I think Jax was talking strictly about maintenance.
And there's a point that is being overlooked here:
It could cost as much or more per hour to maintain a gasoline engine. That $180
oil change costs the same, whether the engines are gas or diesel. Toss in the
cost of an ignition tune-up every so often and the costs associated with
replacing lighter duty parts used for gas engines, and diesel
doesn't compare all that badly.
It isn't as if you could create an argument for $5 an hour to maintain a diesel
engine and then proceed to compare that, fairly, to
$ZERO for a gas burner. Given the price of sails these days, it looks like the
only cheap way to get across the water is to row.
I spend a lot less time and a lot less money keeping my middle aged diesel
running than many of my associates who boat with middle aged gas engines.
Gould 0738
>But remember, there are more than 100 men making
>a full-time living (presumably, a good living) in Ft Lauderdale fixing just
>diesel engines in recreational boats (Pascoe's numbers, and he knows the FtL
>market).
>
Would you be surprised to discover that there are only 36 listings in the Fort
Lauderdale Yellow Pages with the word "diesel" anywhere in the name? Some of
these companies sell new engines, some of them work strictly on tractor
trailers and buses, some are parts houses, etc. Obviously, I haven't gone to FL
to do a census of marine diesel repairmen in Ft. Lauderdale, but either these
guys are all working under the table (in which case it would be tough for
*anybody* to get an accurate count) or a few companies specializing in marine
engine repair have
enormous numbers of technicians. As you know, it's atypical for most shops to
have
any big number of mechanics- most guys
*think* it's easy to set out on their own and
keep a lot more of the $80 an hour. (HA!)
I take that entire essay of Pacoe's with a grain of salt. If I'm not mistaken,
that's the same piece in which he says you need to
be ready to replace the average gas engine
in a boat after 600 hours, and that a diesel
should often be considered worn out at about 1000.
Saying something is so doesn't automatically make it so. DP would find far more
people who, based on actual ownership experience, would disagree with his 600
and 1000 hour
alarmism than would ever agree with him.
JAXAshby
to be at least somewhat lower, for gas engines don't need the special filters,
don'st have expensive injectors, super expensive high pressure fuel pumps, etc.
A direct -- if forgotten -- cost of a diesel engine is the very much required
"emergency anchore" ready at hand to toss overboard when (not if) the fuel
filters clog up. Another cost is the ion generator used to rid the cabin of
diesel smell from changing the filters and bleeding the system. Another cost
is the extra dinner stop you didn't wish to make because your wife was unhappy
with the diesel exhaust smell motoring down wind in a light breeze.
That said, gas engines for sure don't run for free between overhauls.
JAXAshby
>be ready to replace the average gas engine
>in a boat after 600 hours, and that a diesel
>should often be considered worn out at about 1000.
900 hours vs 1,000 hours, and the man is a surveryor of very considerable
experience.
btw, *some* shops that advertise in the Yellow Pages under diesel are more than
one man shops.
btw-s, my nephew as a 21 year diesel mechanic made a rather decent living for
himself and his family. He's still at it and his family is growing.
JAXAshby
I was and I am. I stick to my figures. they are accurate, though, certainly
no one has to believe what they don't wish to believe
>It could cost as much or more per hour to maintain a gasoline engine.
nah. At least not in the recreational marine market.
>... and diesel
>doesn't compare all that badly.
>
not "all that badly", but "just a little bit badly"?
>It isn't as if you could create an argument for $5 an hour to maintain a
>diesel
>engine ...
it's not an arguement, it's an emperical fact.
>... and then proceed to compare that, fairly, to
>$ZERO for a gas burner.
gas engines certainly don't run without maintenance, but a short block rebuild
on a gas engine doesn't cost all that much more than a cyl head rebuild on a
diesel of the high pressure fuel pump.
Engines -- all engines -- require maintenance and a $30,000 diesel engine of
the same hp as a $10,000 gas engine means the per hour cost of the diesel boat
is higher (because the used boat with diesel doesn't get 20 grand more at
resale, and because if you invested that 20 grand [in something, say real
estate] for the life of the boat ownership you'd have more than 20 grand left
over, perhaps even 25 or 30 grand left over. that is a REAL cost of operating
the diesel.)
>Given the price of sails these days, it looks like the
>only cheap way to get across the water is to row.
George Buhler the NA makes that very arguement regarding trawlers vs sailboats
for cruising (for most? many? people). Geo may have a point.
>I spend a lot less time and a lot less money keeping my middle aged diesel
>running than many of my associates who boat with middle aged gas engines.
but the diesel engine cost what? 20 grand more? And for a couple thou they can
have a brand new remanufactured short block delivered to the dock. You're
going to pay more than that just to "rebuild" a cylinder head on a diesel
Jeff Morris
Pascoe where he says the "life expectancy of a marine diesel engine in
a pleasurecraft is somewhere around 1500 hours between major
you actually think this enhances your credibility?
--
-jeff www.sv-loki.com
"The sea was angry that day, my friend. Like an old man trying to send
back soup at the deli."
"JAXAshby" <jaxa...@aol.com> wrote in message
news:20021105094632...@mb-bd.aol.com...
JAXAshby
long ago.
jeffies, let's put this thing in a differenct perspective. let's note that
while you seem to fully beleive in the ten gazillion hour diesel, it is most
assuredly true (from my personal and recent and extensive ongoing direct
experience) that when talking with a sailboat broker and the engine has 2,000
hours or more on the engine you will get zero point zero pushback when you say,
"the engine is a little tired", and the very same lack of pushback for a 1,000+
engine when you say, "the engine may well be in need of some extensive repair".
Believe in gazillion hour engines if you want, but the people who sell used
sailboats don't.
ae...@flight.net
>sorry for the typo, jeffies.
>
>and even *after* allowing for your extremely exagerated claims, a diesel at
>some 3s to 4x to 5x the price is *STILL* a bum deal.
Numbers aside, my neighbors 42 Post has 671-N's, with 4,500 hours on
them. They run like sewing machines, and he expects go get at least
8,000 hours out of them. The bottom end of these engines are
indestructible, given proper maintenance, so new pistons, sleeves and
a rebuild of ancillary components for about $5K per side will result
in "new" engines, likely capable of another 8,000 hours.
It would take me several lifetimes to wear those out..........
The new high RPM diesels are another story..................
DS King
> >and even *after* allowing for your extremely exagerated claims, a diesel at
> >some 3s to 4x to 5x the price is *STILL* a bum deal.
And yet, for some crazy reason, most commercial & industrial users go with
diesel..... gee they must all be stupid, eh JAX?
> ae...@flight.net wrote:
> Numbers aside, my neighbors 42 Post has 671-N's, with 4,500 hours on
> them. They run like sewing machines, and he expects go get at least
> 8,000 hours out of them.
Right now I am looking over a Ford Lehman 135 with a tad less than 2,000 hours
that runs like a top. I expect to get at least that much again before any major
work. I don't know what all these people who get much less time out of their
engines are doing wrong.
Fair Skies- Doug King
Ron M.
when I've gone out on party boats, as I've done on all three coasts.
Some of these head boats have twin or triple 1000 to 1500 HP engines
and run 6 to 8 hours a day (3-4 hours going out, 3-4 hours coming in),
7 days a week.
Anybody know what kind of engines these things use, and how long they
use them? Just curious.
Ron M.
Steven Shelikoff
wrote:
>> jaxa...@aol.com (JAXAshby) wrote:
>> >and even *after* allowing for your extremely exagerated claims, a diesel at
>> >some 3s to 4x to 5x the price is *STILL* a bum deal.
>
>And yet, for some crazy reason, most commercial & industrial users go with
>diesel..... gee they must all be stupid, eh JAX?
If you haven't figured out by now that on almost every subject, Jax is
right and the rest of the world is wrong, you haven't been paying
attention.
Steve
(yeah, I know, go stand in the corner. lmao)
otnmbrd
At one time, worked for an outfit that ran passenger ferries,
sightseeing, and head boats.
All propulsion engines were 71 series Detroit. (at that time).
Would figure, on average, start taking a close look at @ 8,000 hrs, for
possible top end overhaul, if nothing had shown up.
There were a number of variables however ..... one engine (6-71) had
been running in a rather heavy 65' sightseeing boat for about 20 years,
with little other than new fuel pumps and water pumps (plus normal oil
changes, etc.)...... one particular V-12, would lunch itself, once a
season (actually, was a cooling problem with the keel coolers) till it
finally cracked the block.
There are a number of factors that will decide the longevity for a
particular engine, in a particular boat ..... I had ten boats in that
group, and each would draw my attention at a different time, but the
8,000 hrs was the basis ..... some were looked at sooner, some later.
otn
Frederick Owen
parts sales rep for Mack Trucks I had several customers vehicles that would
go 1,000,000 miles without an overhaul. (Over The Road tractors).That was 15
years ago. and I am sure diesel longevity has improved with the advent of
computer controlled fuel injection and design improvements.
"JAXAshby" <jaxa...@aol.com> wrote in message
news:20021105104821...@mb-bd.aol.com...
Eisboch
diesels are 4 strokes.
The Detroits are 2 stroke engines.
Eisboch
Dave Hall
>
> >Yep. And what about amortized cost of replacement or major
> >overhaul? I'm guessing that a major for your Perkins is in the
> >$10K to $15K range, and replacement at about $20K+. If you
> >assume 5,000 hours before either required, then that is another
> >$2.00 to $4.00 per hour. If you then add in things like injector
> >servicing and other routine maintenance, the price goes higher.
> >
> >I'm in the unusual and somewhat uncomfortable position of agreeing
> >that Jax has a valid point here. Say it isn't so!
>
> Well it isn't, exactly. You're including a theoretical sinking fund for
> eventual engine replacement. (The word "sinking fund" should really never ve
> used aboard a boat).
> I think Jax was talking strictly about maintenance.
>
> And there's a point that is being overlooked here:
>
> It could cost as much or more per hour to maintain a gasoline engine. That $180
> oil change costs the same, whether the engines are gas or diesel. Toss in the
> cost of an ignition tune-up every so often and the costs associated with
> replacing lighter duty parts used for gas engines, and diesel
> doesn't compare all that badly.
>
You have to keep in mind the type of diesel engine you have, when
estimating its useful service life. Large, relatively low
horsepower/cubic inch engines typically last a very long time. But
engines that attempt to squeeze the most HP out of their displacement
size, typically have a service life that's not much better than a gas
engine. However, their maintenance and rebuilding costs are as high as
any other diesel.
Dave
John
> I always had boats with one large gas engine and have now decided to switch
> to twin diesel engines.
>
> I have read some months ago a rule of thumb that a well maintained gas
> engine is considered "old", meaning that problems and repairs will start
> getting expensive, after 600-700 hours of operation.
>
> Since I am going to buy a 2nd hand boat with twin diesels does anyone know a
> similar rule of thumb for diesels?
>
> Thanks in advance,
>
> Alex
General rule of thumb, if it's a non-turbo engine or has not been
boosted, HP wise, a lot higher than it's original design, expect 5000
hours or more. The higher the HP rating has been pushed, the more it
comes down, to the point where a very high output engine can go in
2000 hours or less. It's not unheard of for an 8V92 pushing out 735 HP
to go in 1400 hours, where as a 671N can hit 8000 hours. It also has a
lot to do with how the engine was used and maintained, the gearing and
prop size. Pull it back 100 to say 200 RPM from what the manufacturer
says to run it at, and it will last longer. Run it hard or where it's
trying to get up on plane, and you'll get to know the local merchanic
real well.
JAXAshby
well-cared for, well-maintained, well-cooled, well-oiled engine used by a truck
company (whose profits depend on that engine staying running) and a
recreational marine engine.
btw, did you know that many, many, many DC-3 aircraft amassed more than
1,000,000 hours and every last one of them had/have gas engines.
btw, ever hear the story of the ax used personally by Abe Lincoln as a young
boy and still in use today. It's had 35 new handles and 12 new heads since
Abe, but it's the genuine article.
JAXAshby
>diesel..... gee they must all be stupid, eh JAX?
you be a sophist pig, dougies. those are vastly different applications than
recreational marine use.
JAXAshby
a cyl head integral with the cyl. I was intrigued (I'd not heard of such
except on Indy Offy engines and it an extremely expensive way to build engines)
and asked him why he went to the expense.
He said he had to use one-piece cyl heads/cyls because otherwise his customers
wouldn't buy his engines for all the blown cyl head problems those customers
were aware of with two-piece cylinders.
JAXAshby
the life of an engine -- assuming good maintenance, assuming equal piston speed
-- is determined by how strong the disigners made the engine for the hp output.
JAXAshby
>size, typically have a service life that's not much better than a gas
>engine. However, their maintenance and rebuilding costs are as high as
>any other diesel
yup
JAXAshby
environment to need a total rebuild in under 200 hours. Not common, to be
sure, but not unheard of.
Leave dirty oil in the crankcase of a diesel over the winter and see what that
does to engine life expectancy
F330 GT
From what I unserstand, that's why G.M. sold the Detroit Diesel division.
Problems with passing emissions laws. Didn't Penske buy that division?
Steven Shelikoff
>Fred, there is a VAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAST difference in the life of
>well-cared for, well-maintained, well-cooled, well-oiled engine used by a truck
>company (whose profits depend on that engine staying running) and a
>recreational marine engine.
>
>btw, did you know that many, many, many DC-3 aircraft amassed more than
>1,000,000 hours and every last one of them had/have gas engines.
you be a sophist pig, jaxass. those are vastly different applications
than recreational marine use.
Ed
-There are no reliable gas engines on the market that can replace anything
over 400HP (Sorry... I don't consider gas turbines reliable for
recreational use) Here is a typical large GAS vs Diesel case study for under
400HP.
-I removed my 454s in my 34 Phoenix and repowered with 370 Turbo cummins:
454 Gas engines 17 kts-2.5 Gallons per mile @ $3.50 per gallon in the
Bahamas = $8.75 per mile
370 Turbo Diesels 28 Kts at 1 Gallon per mile @ $1.70 per gallon in the
Bahamas = $1.70 per mile
$7.05 savings per mile 7142 miles to pay for Diesels divided by 26 kts = 274
hours of island use for break even.
For US ($2 gas, $.90 diesel delivered = $4.10 per mile difference) = 12K
miles or 470 hours for US use
Another way to look at it.
To run a boat for 4000 hours
Repower cost for diesel = $50,000 for
Gas about $16,000 * 3 (Conservative number of repowers per 1 diesel repower)
If you actually use a boat over >100 hours per year and you have a boat over
20,000 lbs (Power) then Diesel is the only economical option. If your boat
sits at the dock, then go with the gas engines.
After using the above boat for 4 years, I got about 40K more than a gas boat
of the same type so even if you don't use them until they die, you can get
your money out of them. I now have a 48' boat with 671 TIBs. I would
really like to repower it with a pair of 502 GAS engines but I am waiting
for JAX to tell me how... NOT
"JAXAshby" <jaxa...@aol.com> wrote in message
news:20021106143633...@mb-de.aol.com...
SaladinoJA
>From: "Ed" e...@nospam.com
>Date: 11/6/2002 7:42 PM Eastern Standard Time
>Message-id: <3dc9b62e$1...@nopics.sjc>
>For US ($2 gas, $.90 diesel delivered
Is there anyone else here, that doesn't pay $.90 a gallon for fuel oil?
Frederick Owen
Ed
they will deliver to your home a min of 200 gallons for about 90 cents now.
At the pump at a marina it is about 1.40 but you are paying for the cost of
the waterfront property. If you buy from a land based station you pay for
the federal road tax. In the Bahamas, the price of Diesel, being a
commercial fuel, is highly regulated compared to gasoline. Post your fax
number and I will send you a pile of diesel receipts!.
BTW... if you have a private dock, look in the yellow pages for fuel and you
may find a much cheaper source than the local marinas. My supplier also
services the local large computer users for their dyed (not for road use)
diesel that runs their backup generators so you should be able to find a
good supply of dyed diesel in Central Texas, Kansas or other land-locked
areas of the country as well.
"SaladinoJA" <salad...@aol.com> wrote in message
news:20021106201551...@mb-fe.aol.com...
JAXAshby
JAXAshby
If ANYone were to believe you they'd have to believe that a diesel gets 250%
more mileage than the same hp gas engine.
How is it you know something the US EPA with all its scientists never got lucky
enough to stumble onto?
Dude, gallon for gallon, hp for hp a diesel is about 20% more efficient. pound
for pound of fuel burned a diesel is less efficient.
PInc972390
>Problems with passing emissions laws. Didn't Penske buy that division?
>
The 53 - 71 - 92 Series Detroit diesels are 2 stroke. The 60 series Detroits
are 4 Stroke and very fuel efficient so that about 60 percent of the big trucks
on the road are running them.
The two stroke Detroits are not oil injected like an outboard, that takes care
of itself if the Detroit operators know what I am talking about.
Rick
>>more efficient. pound for pound of fuel burned a diesel
>>is less efficient."
That is truly a bizarre statement, Jax. You are somehow comparing apples
to metric footballs ... or something.
The efficiency of an engine does not vary with the means of measuring
the quantity of fuel burned.
If you are trying to discuss fuel efficiency then stick to real
measures, BTU's in vs kW, hp, or any real measure of work out.
For comparative purposes, and for engineering calculations, fuel
consumption in the U.S. is measured in pounds per brake horsepower hour.
The use of that figure, the brake specific fuel consumption, not the
type of nonsensical gibberish so freely posted in this forum, allows
real comparisons of engines.
Rick
sandf...@cs.com
>
>>>btw, did you know that many, many, many DC-3 aircraft amassed more than
>>>1,000,000 hours and every last one of them had/have gas engines.
Bull*&(*
The airframes of many a DC-3 may have made that many hours but none of
the engines did. Ever hear of TBO all aircraft engines have a Top and
bottom overhaul rating and nothing ever hung on a DC 3 has anything
even closse to a million hour rating . Aircraft engines do not last
anywhere near that long. Try top overhauls for engines every 2000 hours
and TBO at around 5000 and you might be right. Most radials get new jugs
along the way.
Offgridman/pilot
JAXAshby
hour -- is about 20% more efficient, and -- when compared on pounds of fuel
burned per hour is less efficient than a gas engine.
*you* get to pick the apples or the oranges.
JAXAshby
Ed
with many other similar sized vessels that have undergone the swap. (Yes I
did have floscans along with accurate logs with sea conditions etc)
The efficiency of a 454 engine goes to hell when pushed beyond 60% of it's
rated HP. A modern diesel stays efficient up to about 90% of it's rated HP.
When you take pair of 454s on a boat with a deep V hull that weighs over
about 15K LBs (Phoenix 34 comes in at about 20K LBs) 60% of rated will
barely put it on plane thus adding to the inefficiencies. Manufactures put
gas in these boats and sell them to people who either don't know any better
or who do not plan to run the boat that often or very far. If you look at
the flow rates provided by the boat mfrs, you will see some similar numbers
but remember, they produce their numbers with the boat pretty empty and as
you fill up a boat with gear, water, fuel, etc the gas engines will have to
work even harder as you fill the boat. A diesel will also have to work
harder but due to the efficiency curves, they will use less additional fuel
per LB of load. Also... Rough seas will prove the diesel is even more
efficient due to the raw torque. In rough seas the gas engine will cycle
from cruise RPM to much less at each wave period, a diesel will fluctuate a
much smaller amount.
If one puts 100 hours a year on a boat or the boat is small, diesels are a
waste. A car with a transmission rarely pushs an engine over 60% so don't
use that analogy
Look up the flow rate, torque and HP at rated RPM of a 454 and compare that
to Cummins diesels or any other modern diesel and then run the numbers. 20%
theoretical will soon translate to 2x ++ in a real application with today's
engines.
BTW JAX, where does your real life experience in this are come from? Ever
own a diesel and compare or are you a pure theorist who just likes to start
newsgroup fights?
"JAXAshby" <jaxa...@aol.com> wrote in message
news:20021106210618...@mb-bd.aol.com...
Steven Shelikoff
>sorry, schjackoff. I forgot that metaphor is beyond you.
Bwahahhaa!!!! You're hilarious! That's your own quote you repied to.
Don't you recognize it you idjiot?
Steve
James Hebert
"Eisboch" <r_er...@bellsouth.net> wrote:
> Here's what I've been told. In the old days a normally aspirated diesel
> (meaning non-turbo) would last longer than you could possibly use it (with
> proper maintenance and attention to fuel quality). Probably the best
> example are the non-turbo Detroit Diesel 671's. They just don't wear out
> and 8000 hours or more is typical before a major overhaul.
A data point:
The pilot vessel here locally (Detroit River) is in operation almost
continually, 24 hours a day. It is powered by a Detroit Diesel 6-71, I
believe. Last fall there was a tragic accident and the boat sunk.
They raised it and did a complete overhaul, finally getting a new
engine. (Original was 1949!) They had lost track of the hours on the old
diesel, having turned over five or six hour meters (i.e., 50,000 hours
plus).
There were probably no original parts left in that engine--it had been
rebuilt many times. The Detroit Diesel shop said it might have had more
hours on it than any other they'd ever seen.
sibale
or 1,000,000/24 = 41666,.. Days
or 1,000,000/24/365 = 114 year of continuous use.
Yeez, an incredibe aircraft
shel...@yawho.com (Steven Shelikoff) wrote in
news:3dc9acf...@cnews.newsguy.com:
JAXAshby
auto manufacturers (with their multi-billion dollar research budgets) nor the
US EPA (with its very committed scientists onboard) can't begin to find??
of course, we ALL realize that the potential exists that YOU have stumbled onto
something incredible and that one hundred years from now people everywhere will
still be talking in hushed tone about engines that run on "The Eddie
Priniciple".
note for anyone who thinks eddie might be onto something. he makes a specific
claim that if true would mean that auto manufacturers could replace the
wretched gas engine in a current model 30 mpg car with a diesel -- of the same
hp, even -- that gets 75 (yup, seven five) mpg.
eddie either be on crack or his is trying ***desparately*** to convince himself
that all that money he spent on those heavy, smelly, noisy, expensive-to-repair
engines are worth it.
Maybe they are. To him.
JAXAshby
bantered about. I never did the math before to check it.
LaBomba182
>yeah, it sounds that way. The million hour claims for DC-3's are often
>bantered about. I never did the math before to check it.
>
No shit!
Capt. Bill
JAXAshby
nope, no shit. but then those things are sixty nearly seventy years old
Gould 0738
>bantered about. I never did the math before to check it.
How many engines on a DC-3? (sorry, don't know my planes that well, I have to
look at the safety instructions when I fly to know what brand of plane I'm on.)
If there are four engines, a single plane might conceivable log a *total* of a
million engine hours in 25 or 30 years, especially if somebody were inclined to
round "up" a couple hundred thou.
Steve
5,000-10,000 hours between overhauls.
As you state "probably no original parts left..." means that it was
overhauled many, many times. The original block might have remained but
there is no wear and tear on the block.
The 6-71 engine must be the most mass produced and common marine engine,
found in all types of equipment and vessels all over the world.
When I was in Cambodia (70's) they were using old navy 180 ft PC Gun Boats
with twin shafts. The propulsion on EACH shaft was called a "quad" with four
V8-71s on each shaft. Sounds complicated, but there were two foward facing
engines clutched/coupled into the reduction gear and two engines facing aft,
similarly attached. Total of eight engines. On the particular vessel that I
visited, the air controls were not functioning and the engineer was sitting
on a chair between the reduction gears where he could reach the clutch
levers for manual shifting. (Hey! This was a 3rd world navy but they managed
to get three of these vessels all the way to Subic Bay Philippines.)
Now these ships were left over from WWII so they were 30-40 years old but I
hardly doubt that they were original since the US Navy routinely exchanged
complete engines when a overhaul was due.
--
My opinion and experience. FWIW
Steve
S/V Good Intentions
Clams Canino
each wing. Italian versions had hair under the wings.
-W
"Gould 0738" <goul...@aol.com> wrote in message
news:20021107105619...@mb-cf.aol.com...
JAXAshby
two.
Rick
>>burned per hour is less efficient ..."
That is truly a bizarre statement, Jax.
Do you know what the term "efficiency" means and what is measured to
obtain a figure which represents a particular type of efficiency?
You seem to be throwing out buzzwords without fully understanding the
relationships among the various parameters which determine the overall
efficiency, efficacy or suitability of a mode of propulsion in or for a
given application.
You are spouting fundamentalist dogma, not engineering knowledge or insight.
Rick
Rick
I challenge you to find a DC-3 / C-47 with much over 100,000 hours total
time.
Don't just reply with some silly statement, find one and cite the source.
Rick
Rick
In an embarrassingly poorly written article at:
http://www.yachtsurvey.com/comparing_diesel_types.htm
"Thus, when the piston comes up and starts compressing the atomized
fuel, it is going to exploded SOONER because the cylinder air
temperature is higher."
So much for Pascoe's "very considerable experience" the guy doesn't
know squat about how a diesel works and his writing on the subject
certainly shows it.
You could probably get more accurate information from a junior high
school science fair project on diesel engines than from the garbage he
has posted on his website.
If he is the best source you can find please spare us your
misinterpretation of his exceedingly poor grasp of the subject.
Rick
Wayne B
telling us a little about YOUR credentials. Pascoe lives in the real
world with real boats and real engines, and he's been doing it
successfully for quite a while. Sometimes the real world does not
jibe neatly with the theoretical side and it's interesting to try and
reconcile the differences.
======================================
Rick
More accurately a fantasy world in which two-stroke diesels make two
revolutions to complete a stroke and four-stroke engines make four,
diesel fuel is atomized and compressed with scavengine air and then
explodes within nanoseconds ...
Have you read the nonsense he has written about diesels on that page? He
may be a successful surveyor but if his writing on diesels is any
indication of his knowledge of marine engines in general I wouldn't let
him into my engine room much less take seriously any machinery "survey"
performed by him.
>>"... YOUR credentials ..."
Sufficient to recognize marine engineering drivel when I read it.
Rick
Gould 0738
I hope he responds to your challenge.
Skipper
> Rick, your entitled to your opinions about Pascoe but how about
> telling us a little about YOUR credentials. Pascoe lives in the real
> world with real boats and real engines, and he's been doing it
> successfully for quite a while. Sometimes the real world does not
> jibe neatly with the theoretical side and it's interesting to try and
> reconcile the differences.
Pascoe is the charlatan here. He is a stable blind cowardly theorist as
his writing prove. Rick has real and diverse boating experience.
--
Skipper
Skipper
Pascoe is too narrow-minded and lacks the courage of his convictions. He
caters to a very small and specialized section of the market and has a
history of spewing misinformation that he later must retract.
--
Skipper
Rick
I hope that it is indeed very small and specialized and is not
representative of those who enjoy the pleasures of boating.
He has not edited the errors in those articles in years. That means that
his readership is either non existent, equally technically illiterate,
or simply doesn't care that the material is hopelessly flawed by
inaccuracies and patently false statements.
His customers would be far better served if he simply deleted those
articles on diesels altogether and just provided links to manufacturers
pages and those of more competent specialist technicians.
The problem I have with Pascoe's rubbish is that it becomes source
material for those with even less understanding of the subject who then
spread an even further distorted version in threads such as this one.
Pascoism:
"The push rods of these engines are also about 33% longer than most 4
stroke engines, creating more rotational mass and therefore more
rotational torque."
Need I offer more?
Rick
Skipper
> Pascoism:
> Need I offer more?
Well said!
--
Skipper
Frederick Owen
Just what are the requirements for (sic)"real and diverse boating
experience".
Also, what are the requirements for someone to be a (sic)"stable blind
cowardly theorist".
I was just curious.
"Skipper" <fair...@cox.net> wrote in message
news:3DCB5E68...@cox.net...
DS King
Rick wrote:
>
> He has not edited the errors in those articles in years. That means that
> his readership is either non existent, equally technically illiterate,
> or simply doesn't care that the material is hopelessly flawed by
> inaccuracies and patently false statements.
Well, look at what he says about hull & deck structures. Some good info
jumbled in with a lot of paranoid raving about the evils of cored laminate.
I wouldn't expect his engine knowledge to be any more in-depth.
>
>
> His customers would be far better served if he simply deleted those
> articles on diesels altogether and just provided links to manufacturers
> pages and those of more competent specialist technicians.
To some extent I agree, but then one thing about Pascoe's web site is that
it does serve to demonstrate just how bad a boat can get and still appear
fine, or just in need of a little TLC. Those who use his website as a
reference source for technical info are going to be left in the lurch, I'm
afraid.
>
>
> The problem I have with Pascoe's rubbish is that it becomes source
> material for those with even less understanding of the subject who then
> spread an even further distorted version in threads such as this one.
Right, but very few readers believe those guys. Forunately, there are more
savvy people around to steer the newsgroup straight ;)
Fair Skies- Doug King
Aaron Lewis
marine propulsion systems?
Another way around this would be for Rick to write better material and
allow Pascoe or others to publish the material with appropriate credit. I
bet that if Rick offered Pascoe a very well written, technially acurate
article on marine propulson, Pascoe would probably be glad to publish it.
Pascoe's message is buyer beware. His articles are his "commercials" to get
people to come to his site (and to use his services as surveyor.) Are they
perfect? No! He is a busy guy, and does not have unlimted time.
Moreover, he is not a professional writer, and writing good technical
material is very difficult.
But, Pascoe's articles all point at one truth, which is: "A boat that looks
pretty at dockside may have expensive problems." Anybody disagree with
that?
Aaron
"Rick" <tu...@dearthlink.not> wrote in message
news:3DCB2FAF...@dearthlink.not...
Rick
It is not a simple matter for everyone, nor is it "very difficult."
Writing technical articles that are accurate, informative, and
contribute to the enlightenment of the reader does, however, require the
writer to acquire a fundamental grasp of the subject.
Pascoe's writing is poor in itself, the product of an untrained writer,
but that is not my objection to his product. He lacks a basic
understanding of his subject. His misapplication of terminology, his
flawed descriptions of processes and his conceptual errors indicate far
more than the common mistakes of an amateur technical writer.
He does not simply describe mechanical processes and arrangements, he
attributes values to those processes and arrangements and attempts to
convince his reader that a certain process or mechanical arrangement is
by its nature good or bad. If he were an expert in the field in which he
writes he might get away with taking a few liberties and editorialize to
some degree. But his descriptions are so flawed, and his understanding
of the function and operation of diesel engines is so poor, that any
editorializing on his part only serves to compound his offense to the
reader.
>>"I bet that if Rick offered Pascoe a very well written,
>>technially acurate article on marine propulson, Pascoe
>>would probably be glad to publish it."
I don't think he can afford me <G> If he had any interest in posting
accurate material he needs only to submit his efforts to copy editing by
one of hundreds of hungry students looking for such work, and technical
review by anyone the least bit literate in the subject. He has obviously
done neither so I can only assume that he has little if any interest in
the accuracy or readability of his articles.
>>"Pascoe's message is buyer beware ..."
And it certainly applies to his own material. It begs the question of
just how accurate and valid are the observations and interpretations
which he sells under the heading of "survey."
Rick
Lloyd Sumpter
(which means the dirty oil is in the engine all winter). Done it for 15
years. Engine now has around 4000 hrs on it, still runs fine. Like to see
a gas engine last for 20 years, 4000 hrs, running mainly 90% throttle or
more, often for over 12 hrs at a time.
Lloyd Sumpter
"Far Cove" Catalina 36
SaladinoJA
>Date: 11/9/2002 2:23 AM Eastern Standard Time
>Message-id: <pan.2002.11.09.07....@shaw.ca>
>I change the oil in Far Cove's engine once a year, in the spring
>(which means the dirty oil is in the engine all winter). Done it for 15
>years. Engine now has around 4000 hrs on it, still runs fine.
I'm not saying your system is wrong, (after all you have the proof that it
works for you right in your boat), but it was always my understanding that it
was preferred, to change the oil in the Fall, also a little more
frequently,depending on the hours during the season. I change my oil when I lay
up the boat in Nov.and then usually twice more during the season,starting in
April. This seems to work for me. (Approx. 300hrs per season)
Lloyd Sumpter
You're absulutely right. I was pointing out that I've abused my engine
for 15 years and it's still running fine. I change it in the spring
because that's when I do my annual maintenance (scrape'n'paint, etc). No
use putting new bottom paint on in the fall.
JAXAshby
pound fuel burned, a gas engine produces more hp per time period.
gallon for gallon, diesel produces more.
(check the weight/gal of each)
JAXAshby
surveyor in "The Yachting Capital of America".
In other words, he's seen a lot of marine recreational boats. When he says
diesels last xxx hours in rec boats, he is someone to be listened to (for he
has both experience AND no axe to grind), a lot like sailboat brokers (who DO
very much have an axe to grind) who near universally do not disagree when one
comments on a boat for sale with 1000+ hours on the engine that "the engine may
be in need of serious attention".
JAXAshby
JAXAshby
Carr makes positively loony statements about the causes of weather, YET his
conclusions are exceptionally accurate.
>He (Pascoe) does not simply describe mechanical processes and arrangements, he
JAXAshby
bearings deserve each other.
Steven Shelikoff
>no, rick, it's not bizarre at all. It means exactly as it says, that pound for
>pound fuel burned, a gas engine produces more hp per time period.
>
>gallon for gallon, diesel produces more.
>
>(check the weight/gal of each)
Gas is about 6.1 lbs/gal for about 125,000 BTU/gal. That's about 20,492
BTU/lb.
Diesel is about 7.2 lbs/gal for about 140,000 BTU/gal. That's about
19,445 BTU/lb.
That's only about 5% less energy per pound. The diesel's greater
efficiency (the difference in efficiency is greater than 5%) more than
makes up for that.
Another way to look at it is that in marine applications, a typical gas
engine burns about 0.1gal/hr/hp, which is 0.6lbs/hr/hp. A typical
diesel burns about 0.055gal/hr/hp, which is about 0.4lbs/hr/hp.
So either way you look at it, Jax is wrong again.
Steve
JAXAshby
>efficiency (the difference in efficiency is greater than 5%) more than
>makes up for that.
jackoff, you're wrong.
again. and again. and again. and again. and again. and again. and again.
and again. and again. and again. and again. and again. and again. and
again. and again. and again. ..................
Rick
>>produces more hp per time period."
Dear deluded Jax ... Why do you insist on making a fool of yourself this
way? I will make one final attempt to put this in terms which you might
understand.
The fuel efficiency of an engine is measured by weighing the fuel burned
to produce one horsepower (SAE) or one kilowatt (Metric) for one hour.
The resulting figure is called the Brake Specific Fuel Consumption. If
we measure pounds and horsepower it is described in pounds per
horsepower hour. If we measure it in the metric system it is described
as grams per kilowatt hour.
Most manufacturers provide the BSFC figure in both units nowadays so you
should be able to cross reference to a unit in which you are comfortable.
Current marine gasoline engines in the power output range of 100 to
around 300 horsepower, when operated near maximum continuos output,
consume fuel at around 350 grams/kW/hr.
Diesel engines of similar output when operated in the same conditions
consume fuel at around 220 - 260 grams/kW/hr.
Using the figures for BTU's per pound and pounds per gallon provided by
Steven since they are well within the range of variability, the BSFC of
a diesel indicates that it converts about 11,000 BTU's into a kW/hr of
work. The equivalent gasoline engine converts nearly 16,000 BTU's to
produce that same kW/hr. Since the number of BTU's in a kW/hr (3412) are
exactly the same in a gasoline engine, diesel engine, windmill, squirrel
cage, or your favorite hand, it should be obvious to you that your
delusions regarding gasoline and diesel engines are in any way founded
in reality.
I cannot begin to image how you will respond in an attempt to counter
this post but, I must admit, I am looking forward to it. The perversity
of your mind when it strays into engineering matters is truly a thing to
behold.
Rick
Rick
>>gasoline and diesel engines are in any way founded in reality."
Oops, that should have been:
... your delusions regarding gasoline and diesel engines are NOT in any
way founded in reality.
Rick
JAXAshby
the US EPA for gas vs diesel autos, an org that has been measuring relative
fuel consumption for nearly three decades.
If it is all the same to you, I'll accept their figures, to witt: hp for hp,
diesel gets about 25% mileage per GALLON. And per your figures, diesel weighs
about 33% more per gallon than gas.
Tom Knight
over and over. How's your boat going?
"Rick" <tu...@dearthlink.not> wrote in message
news:3DCF4154...@dearthlink.not...
JAXAshby
and that *YOU* know if auto manufacturers would *allow* diesel engines in their
cars that the fuel mileage on a 30 mpg car would jump immediately to 75 mpg.
don't let facts get your way, what ever you do, tom.
Steven Shelikoff
>rick, your figures do NOT even begin to match up with the figures published by
>the US EPA for gas vs diesel autos, an org that has been measuring relative
>fuel consumption for nearly three decades.
>
>If it is all the same to you, I'll accept their figures, to witt: hp for hp,
>diesel gets about 25% mileage per GALLON. And per your figures, diesel weighs
>about 33% more per gallon than gas.
No wonder you're so confused. You're talking about EPA figures for cars
and the rest of us are talking about boats. Wayyyyy different.
Steve
JAXAshby
them) are too stupid to notice how much better marine diesel engines are than
auto/truck diesel engines.
Brad Taylor
about boats, and in fact I doubt hat you even own one. Everytime you get
into a discussion about boat engines and start to lose, you immediately
start referencing cars. Get with it. This is a newsgroup that is for
people who want to discuss boats. They differ in myriad ways from
cars....... idiot.
"JAXAshby" <jaxa...@aol.com> wrote in message
news:20021111064405...@mb-fk.aol.com...
Rick
>>been measuring relative fuel consumption for nearly three decades.
Dear Deluded,
Please look at this study performed by Argonne National Laboratory for
General Motors.
http://www.transportation.anl.gov/ttrdc/pdfs/TA/164.pdf
It is a "Tank to Wheel" survey of automotive efficiency comparisons
among conventional and several hybrid propulsion modes. I suggest you
ignore the hybrid types as it will confuse you, pay close attention to
what GM calls Conventional Gasoline and Compression Ignition Direct
Injection which means diesel.
There is a wealth of data in this study but let me distill it for you as
I know that too much information tends to distract you.
Refer to Table 3.8 in the above study.
Gasoline engines operating in the range of the 50th percentile require
6950 BTU's to travel one mile.
Diesel engines operating in the range of the 50th percentile require
5740 BTU's to travel one mile.
Since you like the folks at EPA, take a look here:
http://www.epa.gov/otaq/models/mobile6/m6hde004.pdf
In case you choose not to, or for those who don't want to bother, the
EPA table 8 lists several years of BSFC for gasoline vs diesel powered
buses and trucks. A typical example is for intercity vehicles in 1994;
gasoline powered vehicles had a BSFC of .568 lb/hp/hr
diesel powered vehicles had a BSFC of .399 lb/hp/hr
IF that needs translating, Jax, .399 is a lot more efficient use of fuel
than .568 ... it means that the diesel used 3864 fewer BTU's to produce
the same amount of work.
In simple terms Jax, your head is up your ass again. Give it up man, you
have been shown wrong, you have been shown the facts, yet you continue
to defy reality. Are you some kind of masochist or is this the only
excitement in your life?
Every single time you post any sort of technical information you are
wrong, it is bizarre how consistent you are in posting nonsense. It has
to be a planned pattern of behaviour because even a stopped clock is
correct twice a day ... you haven't been right about engines twice that
I can recall in the years I have been following this group.
Rick
Steven Shelikoff
>of course, shjackoff, marine diesels are magic. Or auto engineers (the mass of
>them) are too stupid to notice how much better marine diesel engines are than
>auto/truck diesel engines.
JaxAshby wrote:
>DS King wrote:
>>And yet, for some crazy reason, most commercial & industrial users go with
>>diesel..... gee they must all be stupid, eh JAX?
>you be a sophist pig, dougies. those are vastly different applications than
>recreational marine use.
Jax, you be a sophist pig.
Steve
JAXAshby
is the physics of marine engines is totally and completely different from any
other engines, even if they are the very same engine just mounted in different
vehicles.
nice, brad. nice.
now go stand in the corner and be quiet.
JAXAshby
done by researchers without a bias.
Disregard their findings if you want, but allow the rest of us to judge your
bias in your doing so.