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Old 05-07-2016, 20:22   #46
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Re: Running my engine hard?

The majority of the above is lumping very diffrent engines together with the only common denominator being they run diesel fuel and are on boats. A naturaly aspirated Perkins 4108 will certainly not have the same ideal operational charactoristic as a new turbochargered Yanmar. Most small boat engines also carry pleasure craft ratings that can varry drastically between manufacture. For generalizations I would agree with a64pilot in recommending operating at constant load around 80% when possible. Once the rings are seated in a rebuilt or new engine there really shouldn't be any reason to run it at 100% provided it doesn't see extended periods of running at little or no load. Basically as long as things stay clean inside they will remain so, once they get too dirty and fouled there really are not shortcuts without damaging things to get it back. Also.... intake air and wet exhuast systems can get ovelooked as a factor in poor perfomance, too small or too long creating too much backpressure leading to all sorts of fun. Carbon build up in a engine is poor combustion, pretty straight forward.
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Old 05-07-2016, 21:37   #47
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Re: Running my engine hard?

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Originally Posted by Jim Cate View Post
How do you explain diesel gen sets that run for thousands of hours, always at the same governed RPM? They don't get the dread glazing, do t hey?

Jim
Jim, good point. I wonder that too.
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Old 05-07-2016, 22:34   #48
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Re: Running my engine hard?

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Jim they actually can, if not run under a load. Lots of standby generators that are run every so often, but not brought online so they are under a load end up with what is called wet stacking or Diesel slobber, and glazed cylinder walls.
Interesting. That must cost a fortune, I did a live event last year with maybe a dozen big gennies running 24/7 for 6 months straight, almost always with hardly any load. How much must aggreko pay on maintenance?
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Old 06-07-2016, 10:42   #49
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Re: Running my engine hard?

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Interesting. That must cost a fortune, I did a live event last year with maybe a dozen big gennies running 24/7 for 6 months straight, almost always with hardly any load. How much must aggreko pay on maintenance?

Not really the same thing, a little northern lights in a boat vs. a 1200kw Cummins in a can. Newer common rail diesels are much more adaptable to varying load as they are fuel injected electronically. The operational hrs between commercial and rec are quite different. A in frame at 30,000 hrs sounds like a long was away, unless its getting 7,000 hrs of run time a year.

We had a coupel Cummisn QSK50's on the last boat I waso nand it was pretty cool to see a injector take a **** and the engine really not care, it just compensated via the other cylinders.
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Old 06-07-2016, 10:52   #50
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Re: Running my engine hard?

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Originally Posted by Jim Cate View Post
How do you explain diesel gen sets that run for thousands of hours, always at the same governed RPM? They don't get the dread glazing, do t hey?

Jim
It comes down to the duty cycle they were built for. Those build for a continuous duty cycle are heavier than hell. Not practical for most aux. applications or even something like a sport fisherman. I think the latter two come down to an attempt to get the most HP/Lb.. A working vessel generally just need a continuous duty cycle and weight isn't a concern. MHO
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Old 06-07-2016, 11:08   #51
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Re: Running my engine hard?

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Originally Posted by conachair View Post
Interesting. That must cost a fortune, I did a live event last year with maybe a dozen big gennies running 24/7 for 6 months straight, almost always with hardly any load. How much must aggreko pay on maintenance?

There is a LOT of disagreement on just how much damage is done by Wet Stacking / Diesel Slobbering and not running an engine under load etc. You can find studies done by the US Army that indicate little if any damage is incurred, quite to the contrary of what most of us shade tree mechanics think. Army has many thousands of Diesels that are not often run and put under a load, but sit in motor pools and if they are lucky, get run a little on a weekly basis or just sit.

Many, many years ago US Army went to SOAP or spectrographic oil analysis program, now it's not uncommon at all for an engine to not get it's oil changed for years, cause oil change only happens when the SOAP says to, another Sin to us shade tree types.

I run an engine hard every so often as I believe it's good to do so, but only for a short while, and not all that often.
I don't run it at 80% power continuously, mostly cause I can't stand the noise, but if you can, and want to, it should handle it. Above 2000 RPM and the thing just grates on my nerves.
I don't think percent power follows RPM all that well, I bet the last 25% power is actually in a pretty narrow range of RPM, for example I believe my 4-JHE is 44 HP at 3600, and drops 10% to 40 HP in only 100 RPM to 40 at 3500, and I bet drops another 10% in another 100 or maybe 200 RPM.
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Old 06-07-2016, 21:56   #52
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Re: Running my engine hard?

I've always been in the 80% rpm 80% of the time camp, this is a 3gm30f yanmar, I run between 2600-2800rpm. In another life I was actually a motor mechanic, but the reality is I don't really have a clue, I'm just doing what I've read and believe to be right.
Two days ago I met a bloke on a Tayana 37. He has a 55hp Yanmar which he fitted 2002, it has just over 14000 hours on it! He uses it very regularly and tells me he very rarely pushes above 2000 rpm and never takes it to high rpm to blow carbon out. So that blows my how to run your yanmar theory!
Hes just purchased a new yanmar but hasn't fitted it yet, hes putting a new one in only because of the high hours on his current engine not that it has stopped or given him any trouble. He travels remote and needs reliability.


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