Fuel consumption at low speed?
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The friendliest place on the web for anyone who enjoys boating.
If you have answers, please help by responding to the unanswered posts.
If you have answers, please help by responding to the unanswered posts.
Yes, a turbo'd engine does wear out faster, and the exhaust gas is HOT, so it heats up the intake side of the turbo, and even the air off the other side that pumps up the engine is hot because it's compressed. So, now you have intercoolers. And, you're boosting the manifold pressure on the engine, sometimes significantly and that causes issues. There's just a LOT of wear and maintenance with turbos... it's a fact of life. Just one more thing to break. I could argue KISS.
However, technology is much better today and it's probably a better installation but no free lunch.
I've got no issue if someone wants one, but not for me.
markpierce
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Ski in NC
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Road tractor engines are all turbo and they often make a million miles. Freighter engines are all turbo. Modern engines are designed for the mechanical and thermal stresses that come with turbocharging. Designed right and run right, they last just as long as a nat.
FF
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"Designed right and run right, they last just as long as a nat."
No questoin , the hassle is "run right" .
A bigger engine run at the trawler crawl may not need enough power to work the turbo.
Then it simply is an obstruction in the exhaust.
A 400 hp engine running on 2GPH may not be a happy or long lived engine.
No questoin , the hassle is "run right" .
A bigger engine run at the trawler crawl may not need enough power to work the turbo.
Then it simply is an obstruction in the exhaust.
A 400 hp engine running on 2GPH may not be a happy or long lived engine.
Ski in NC
Technical Guru
True, running too easy is not great for the engines. But a 400hp turbo engine running at 35hp is pretty similar to the same block non turbo rated for say 150hp also making 35hp.
I run my 450hp at 1.9gph. I know it is not best for it, but so far at 3600hrs, no ill effects noticed. If I have to put cylinder kits in, it will probably cost less than the fuel I've saved.
I run my 450hp at 1.9gph. I know it is not best for it, but so far at 3600hrs, no ill effects noticed. If I have to put cylinder kits in, it will probably cost less than the fuel I've saved.
DonF
Member
Not really the same engine
Generally speaking it's not the same engine. Pistons, rods, crank, even water passages are different between a turbo and naturally aspirated engine. Or even a small turbo vs a large turbo. About the only thing the same is the displacement.
Generally speaking it's not the same engine. Pistons, rods, crank, even water passages are different between a turbo and naturally aspirated engine. Or even a small turbo vs a large turbo. About the only thing the same is the displacement.
DonF
Member
Seevee I suggest you check on Boatdiesel.com most turbo charged engines get better fuel economy than their naturally aspirated version.
Most new diesels are turbo charged to meet emissions standards.
I'm not a big fan of turbos but that's because of the KISS principle. I'm willing to spend a bit more on fuel to have a simpler and easier to work on engine.
Last edited:
FF
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"But a 400hp turbo engine running at 35hp is pretty similar to the same block non turbo rated for say 150hp also making 35hp."
Frequently the base compression ratio is Lowered for the turbo engine which requires even more throttle to get the turbo to create pressure.
The rings seal because of combustion pressure behind them.
Too low a combustion pressure and the seal is lost blowby is a result , as is carbon deposits behind the rings.
Blowby can be handled with more frequent oil changes.
carbon behind the rings MIGHT be handled with one of the outboard carbon cleaners?
Frequently the base compression ratio is Lowered for the turbo engine which requires even more throttle to get the turbo to create pressure.
The rings seal because of combustion pressure behind them.
Too low a combustion pressure and the seal is lost blowby is a result , as is carbon deposits behind the rings.
Blowby can be handled with more frequent oil changes.
carbon behind the rings MIGHT be handled with one of the outboard carbon cleaners?
sunchaser
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Where can you buy a new non turbo Diesel engine? Kinda like trying to buy an internal combustion engine without pistons. There is no downside to a well designed turbo diesel, only advantages if you operate the engine for a combination of weight, size, best BSFC and cost. It has been this way for nearly a century.
Interesting to see auto gas engines going forward are mostly turbo to meet CAFE and emission requirements. A Ford pickup with a little turboed gas engine - what gives?
Of course one can avoid this whole discussion by buying a Tesla. Just don't plan on a cross country trip though.
Lost Horizons
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One example of a just released model: http://www.yanmarmarine.com/theme/y...tasheet/English/Yanmar-4JH57CommonRail-HR.pdf
sunchaser
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Good point LH. Several small diesels for auxiliary, gensets, farm equipment, fire pumps and small backhoes are excused from meeting emissions mandates.
VW elected to excuse themselves, many billions later ---
VW elected to excuse themselves, many billions later ---
Lost Horizons
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Actually, specs say it meets Tier 3.
Fletcher500
Guru
Also, the turbo is not turning running full time. I don't recall the exact loads, but I believe my Volvo turbo comes in to the equation at approx 30 percent engine load, and then spools up accordingly as more throttle is applied. Not sure if any of that is meaningful to the discussion, just an observation.
The Volvo 370, D6 is also supercharged, so another reason they can get 370 hp out of a 5.7 liter engine, along with common rail injection.. Talk about cramming air in. I know some will say that is over doing it, but there are a lot of these engines out there. The commercial fisherman use them, hard, thousands of hours, with good results.
The Volvo 370, D6 is also supercharged, so another reason they can get 370 hp out of a 5.7 liter engine, along with common rail injection.. Talk about cramming air in. I know some will say that is over doing it, but there are a lot of these engines out there. The commercial fisherman use them, hard, thousands of hours, with good results.
Funny, the engine you refer too has something else that people were screaming and yelling hate toward not long ago. That is "Common Rail." Yet now, common rail has proven itself and is accepted as an excellent development. I like Turbo, I like Common Rail. Neither scares me today. I wouldn't have wanted to have bought the first of either, however. I do wait for issues to be worked out.
Turbo in cars has Chrysler to thank. Pontiac had turbos with virtually no warranty and known for many problems. Chrysler put their first turbo's in and they gave them the full warranty they gave other engines. I'm not sure but I think that was in the 10 year, 100,000 mile period. May have just been 7/70,000. Regardless, they were willing to stand behind it so people bought it. It's much like how Hyundai became big in the US. Price was attractive but people were scared of them. However, the warranty's they offered convinced people it was safe to buy and shook up the entire industry.
Rebel112r
Guru
The superchargers on some of the Volvos were to provide boost from idle rpm up to approx 2300 rpm, when the turbo started doing its work. They are belt driven and have an electric clutch. They work very well getting planing boats up on step. Also, even though the term common rail was not around, weren't Detroit Diesels, say the 71 series common rail. I realize the pressures are a lot different and the injectors work differently, but the fuel did flow thru a common line.
Fletcher500
Guru
Mine is belt driven as you note, so it's directly coupled to the engine and boosting as the crankshaft rpm increases. I am not aware of an electric clutch?
Rebel112r
Guru
http://www.volvopentastore.com/mall/image/view/1/2/27672_1.png
#3 is the clutch. Some Volvo D6's may provide supercharging all the time. None that I am familiar with.
#3 is the clutch. Some Volvo D6's may provide supercharging all the time. None that I am familiar with.
Lost Horizons
Senior Member
Turbos in cars have European taxes to thank. They tax cars according to engine volumes there. I have no idea why anyone would want a turbocharged car in America if they wanted to keep it past 4/50 warranty term. Good bye, BMW.
Performance. The reason I've had turbo after turbo, from Chrysler to SAAB, you name it. And I've averaged keeping them 7 years with no problems, putting about 85,000 miles on average on them.
Lost Horizons
Senior Member
I have no problem with a naturally aspirated Lexus GS performance.
That's you. I have no problem with Turbos.
Lost Horizons
Senior Member
Nor do you have a performance advantage.
Wifey B: I do. 194 mph, 0 to 60 in 3 seconds. 3.8L, six cylinder, twin turbo.
So now that's resolved, you don't like turbos, we don't have a problem with them. That's fine, except more and more they become standard on boat engines.
My car is faster than hubby's, although not like we ever run either one of them fast.
Lost Horizons
Senior Member
Good. Almost like an electrocar.
Wifey B: Might have bought a Tesla if they'd still made the convertible. I prefer to go topless though so sedans don't work.
