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Old 05-06-2015, 09:34 AM   #101
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Today's emissions specs and the mandated ultra low sulphur diesel fuel formulae have driven current engine manufacturers to turbocharging. Hotter engines burn cleaner and that's going to be the new normal going forward. Sadly tier4 is such a high bar that most of the tf member's engines won't ever be able to pass, even with the addition of turbos after coolers exhaust scrubbers etc...

As far as shutting down a hot turbo, I had a damper plate disintegrate after an hour of running at 2000 rpm and I deliberately ran the engine in neutral reducing rpm periodically to cool it down. I learned the importance of keeping turbo bearings from coking up from the air cooled Porsche turbo days.


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Old 05-06-2015, 10:26 AM   #102
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So it's emissions standards that make the turbo std equipment on larger engines and different emissions standards allow the smaller engines to be sold w/o turbos. The 4cyl JD must be the upper end of the lower standard NA engines at the moment .. but due to change soon re something Sunchaser said.

Suits me w my little engine.

I know Yanmars aren't quite typical engines but is the the low specific fuel burn the rpm point of greatest efficiency? I see on Larry's JH Yanmar that point is close to 3500rpm. Even high for that 3800rpm engine. Seems from recall that most 2500rpm engines have the lowest specific consumption down at around 1800. A much greater percentage of rpm down from rated power. The JD is 700rpm down. That's where I run my small Mitsu .. 700 down. Is that typical of the lowest fuel burn? I ask of those that browse such information regularly. Also as I recall those typical specific fuel burn curves are representive of WOT. If that's correct how do they vary at low loads that trawlers run at?
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Old 05-06-2015, 11:16 AM   #103
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My understanding from reading the EPA regulations is that Tier 4 engines will not be mandated on smaller diesels used on boats. At least not for the next few years.

The problem is that Tier 4 engines are almost certainly going to require DEF. An engine might use between .1 and .3 gallons of DEF for each gallon of diesel burned. That does not sound like much but if you have 2,000 gallons of fuel on board you know need a 60 gallon tank to hold the DEF. A 60 gallon tank is going to take up some important space. Do you take out fuel tankage, water storage, food lockers, the wifes shoe storage? This is getting serious.

The bigger problem with DEF is that if you run out, the engine will run at reduced power levels. I can just see that happening in a storm, going over a bar, in a pass against the tide, etc...

Hopefully, my understanding of the Tier 4 requirements is correct AND EPA does not mandate these requirements. Tier 3 is bad enough.

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Old 05-06-2015, 11:23 AM   #104
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DEF is an additive?

Would be nice to know.

Never heard of it.
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Old 05-06-2015, 11:38 AM   #105
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DEF is an additive?

Would be nice to know.

Never heard of it.
Yes, my bad. I had meant to spell out DEF but forgot.

DEF is Diesel Exhaust Fluid and is used to clean up the particulates. DEF is water and urea. I have wondered if I can just use rain water or water from a water make and pee into a tank to make my own DEF?

A Ford pickup truck diesel engine a generation or so back, used diesel to burn the particulate build up from the filter. Owners were reporting really bad MPG because they were burning far more diesel to clean out the filter than was expected. The advantage of using diesel to clean the filter was that it was already on the truck and did not require another tank a fluid to buy but the fuel burn could be high/expensive so they moved to using DEF.

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Old 05-06-2015, 11:51 AM   #106
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My understanding from reading the EPA regulations is that Tier 4 engines will not be mandated on smaller diesels used on boats. At least not for the next few years.

The problem is that Tier 4 engines are almost certainly going to require DEF. An engine might use between .1 and .3 gallons of DEF for each gallon of diesel burned. That does not sound like much but if you have 2,000 gallons of fuel on board you know need a 60 gallon tank to hold the DEF. A 60 gallon tank is going to take up some important space. Do you take out fuel tankage, water storage, food lockers, the wifes shoe storage? This is getting serious.

The bigger problem with DEF is that if you run out, the engine will run at reduced power levels. I can just see that happening in a storm, going over a bar, in a pass against the tide, etc...

Hopefully, my understanding of the Tier 4 requirements is correct AND EPA does not mandate these requirements. Tier 3 is bad enough.

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Catalytic Converter. No, I'm not saying that, but I'm suggesting the ultimate answer may be similar in terms of function. There is a product for generators developed by one who I believe may even be a member here. It is SeaClean.

SeaClean | DeAngelo Marine

There will likely be multiple changes required to clean up diesel exhaust. If it follows as it did with gas, it will include the product itself, so the fuel from the start, changes in the engines themselves, and some form of treatment from exhaust.

You look at gasoline powered automobiles today vs a few decades ago and the difference is huge. They're requiring less fuel, they're burning it more efficiently, and they're producing less polluted exhaust.
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Old 05-06-2015, 11:59 AM   #107
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"

For a specific type boat , one engine would be the clear winner.

This is called a fuel map , and is harder to come by than plans for a T-88 small nuke.


Yes, for all the marketing reasons we have talked about for years.

Turbos will add to Hp when needed for hill climbing , or in marine applications give somewhat better fuel burn per HP IF the unit is operated with positive boost and a proper EGT from the load.

I don't understand what you are trying to say.

Turbos give you more power per engine volume, displacement.

The danger/hassle with turbos is two fold.

The turbo and all its inter-coolers hurts efficiency till the engine is on the turbo.

No boost is bad , but 5-30 lbs will help , depending.

The other hassle is after a big high boost load the turbo is hot , usually glowing red.

The turbo must be allowed to cool down enough so its lube oil does not burn or coke .

In this case 5 min of idle to help the turbo life is worth the idle time slight hassles from no load running.

Many folks will spend more time ideling than is required for cooling attempting to enter their slip.
Yep.
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Old 05-06-2015, 12:06 PM   #108
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So it's emissions standards that make the turbo std equipment on larger engines ?
And higher power output and improved efficiency.
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Old 05-06-2015, 12:17 PM   #109
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And higher power output and improved efficiency.
Higher output. Yes.

Reduced consumption st lower rpms, YES.

Improved efficiency, ? show me the numbers.
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Old 05-06-2015, 12:22 PM   #110
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Makes me think that the premise of too hot turbo shut down often mentioned is 99% an non plus. Am I correct... ?
Yes, for those of us who abide by no wake zones. After a "hard" run of 5 to 10 psi boost and not headed to a slip, a turbo trawler diesel boater likely is headed to an anchorage, where it takes about 10 minutes to find the right spot to get the anchor set. Never seen mine red hot, but heck they have the magic no roast paint still looking as good as new.

But wait, in FL the diesel go fasts race to the dock like Sonny Crockett and most certainly must cook their turbos (you heard it here) on a routine basis as they sip their Pisco sours ogling babes. Sounds kinda fun.
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Old 05-06-2015, 01:03 PM   #111
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...
There will likely be multiple changes required to clean up diesel exhaust. If it follows as it did with gas, it will include the product itself, so the fuel from the start, changes in the engines themselves, and some form of treatment from exhaust.

You look at gasoline powered automobiles today vs a few decades ago and the difference is huge. They're requiring less fuel, they're burning it more efficiently, and they're producing less polluted exhaust.
Diesel was cleaned up years ago which is one of the reasons for the higher price of fuel vs gas compared to the prices prior to ULSD.

One could by an inexpensive car in the 80's that would get an honest 50 mpg. On Gas. Not sure that is true today. Certainly a car today is producing less pollution but at some point we cross a point where we are spending a fortune for very little benefit.

One question I have about pollution and marine diesels with wet exhausts, has the EPA measured the soot pollution from said configurations? Does the wet exhaust remove/reduce the soot?

Having an electrical system to remove the soot would be better than having to use DEF, but I question Tier III for small boats. In the JD case I mentioned earlier, Tier III is going to burn more fuel. The engine is not more efficient than the Tier II engine.

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Old 05-06-2015, 01:11 PM   #112
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Improved efficiency, ? show me the numbers.
Many SAE papers and studies in this regard, but to keep it simple I'll cite our old friend at boatdiesel


Fuel and Horsepower
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Old 05-06-2015, 01:39 PM   #113
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Diesel was cleaned up years ago which is one of the reasons for the higher price of fuel vs gas compared to the prices prior to ULSD. Dan
I was surprised to see diesel at $2.48/gallon and regular gas at $2.75 a few days ago at same shore station. Fluke or is something local happening in gas glut/diesel shortage quandary?
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Old 05-06-2015, 01:47 PM   #114
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I was surprised to see diesel at $2.48/gallon and regular gas at $2.75 a few days ago at same shore station. Fluke or is something local happening in gas glut/diesel shortage quandary?
WHERE WHERE WHERE!

Diesel here is 2.79 at most stations with 87 gas about 30-40 cents cheaper. I wonder if the clerk dialed in the wrong numbers.

In my truck's log book I have paid under $1 per gallon for diesel but that was before USLD, higher diesel fuel taxes, and higher demand drove the price over 87 gas.

The drop in fuel prices has sent the local fuel prices all over the place. Stations that used to be the most expensive are not now and the cheaper places can be the most expensive. The stations have to guess the future cost of fuel for the next purchase and some times they are going high or sometimes low. I think the volatility of prices is driving them nuts.

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Old 05-06-2015, 01:58 PM   #115
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You can't put a non Tier III compliant engine in a new boat, so for us, using an mechanical engine in a US documented boat, is not possible. I would LOVE for someone to prove me wrong!
No one here has a "new" boat. Manufacturers and dealers have all of them.
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Old 05-06-2015, 02:01 PM   #116
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Diesel weighs more than gas , so there is more there , there.

You pay for what you get , hydrocarbons to burn.

"I think the volatility of prices is driving them nuts. "

No what drives the cost of gas is the requirement for 44 different gasoline mixtures , by Zip code.
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Old 05-06-2015, 02:13 PM   #117
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Old 05-06-2015, 02:17 PM   #118
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Hmmm.... Full load peak torque for our 6CTAs is indeed right at 1700 RPMs. Looks like fuel consumption (prop curve) at 1700 RPMs would be about 7 GPH, per engine. Don't have our speed tests file here, but I'll compare that as soon as I can. Seems to me, the hull is a pig at 1700 RPMs, though...

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1700 might be a happy spot for the engine, but might be horrible for the boat!!

My boat is ok but not great at 1700, but likes 1900-1950. Close enough for me.

Both engine AND boat must be happy with cruise rpm.

Just a rule of thumb. Real sea trial data are much better.

Checking our speed tests... 1500/1600/1700 RPMs is in our no man's land, can't plane, mostly plowing. 1800 RPMs is the slowest on-plane speed I tried, and to get there I have to go faster (get properly up on plane) and then pull it back down.

For us, then, 1800 RPMs is approx.13.3 kts and it's still a little "plowy."

I don't have fuel flow scan meters, so can only guess at consumption and economy. The fuel consumption curve suggests 8 GPH per engine, so 16 GPH total, and at 13.3 kts that'd be .88 NMPG.

But the boat is more comfortable at:
- 2000 RPMs, 20.8 GPH, 17.50 kts, .84 NMPG, or
- 2200 RPMs, 26.8 GPH, 20.65 kts, .77 NMPG.

And the hull really performs best -- on plane -- at 2400 RPMs, 34.8 GPH, 23.20 kts, .67 NMPG.

No good news there. We usually run at about 7-8 kts, just below hull speed.

Unless weather and sea states dictate faster speeds, in which case we try 2000, if that doesn't work, 2200, if that doesn't work 2400... or whatever else it takes to make the ride comfortable.

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Old 05-06-2015, 04:54 PM   #119
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I was surprised to see diesel at $2.48/gallon and regular gas at $2.75 a few days ago at same shore station. Fluke or is something local happening in gas glut/diesel shortage quandary?
Me too. My local Chevron dealer is selling diesel at $3.05 and gas (California summer blend) for $3.75! (The refinery is only 20 miles away.)
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Old 05-06-2015, 06:21 PM   #120
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Many SAE papers and studies in this regard, but to keep it simple I'll cite our old friend at boatdiesel

Fuel and Horsepower
Thank you.

I can live with that number, 7 to 10% increased efficiency in BFSC.

In the bigger picture though, it doesn't change my point, that to get a 10% increase in fuel efficiency, one pays 50% more for the engine, and that extra cost will never be recouped.

Though for an over the road trucker it well be.

Good point.
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