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Old 12-18-2016, 05:18 PM   #21
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So, one observation... There is a difference in engines that modern design practices bring to the table. Once upon a time, engineers made things strong by adding material. Today, with CAD design, this is no longer as necessary. Even engines designed in the days before modern CAD that are still in production benefit from constant upgrades driven by newer technologies. Certainly the Cummins QSB6.7 is much different from its predecessors...and it appears to be very reliable in its current form.
So, the question of "turbo or not" might change depending on the age of the engine in question...
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Old 12-18-2016, 05:19 PM   #22
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Wifey B: My turbo car has power at all rpm's. 530 hp or so, 0 to 60 in 3 seconds.
That must be one hell f a grocery getter!
Forgive me, that was sexist wasn't it?!?!
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Old 12-18-2016, 05:21 PM   #23
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Wifey B: My turbo car has power at all rpm's. 530 hp or so, 0 to 60 in 3 seconds.
But is it a diesel? And not "exotic"?
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Old 12-18-2016, 05:31 PM   #24
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But is it a diesel? And not "exotic"?
Wifey B: It won't hold many groceries, but then I don't do much grocery shopping. Not a diesel. Define exotic It's a production car, not a custom build.
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Old 12-18-2016, 05:32 PM   #25
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As to turbo cars, disagree, my turbo diesel car has heaps of torque and power and response down low. Plenty of (non exotic)performance cars have a diesel option.
As to boats, agree. I`d rather a big slow revving naturally aspirated diesel than a high rpm turbo diesel, it`s just another layer of maintenance and potential for trouble. But, as said above, for new engines, no non turbo option.
Of course not talking about high end sportcar where a turbo is not there to be able to have a smaller engine but there to increase power output from an already hyper powerful engine. But most of the case, the goal of adding turbo to a car engine is not to get a diabolic engine, it is only to be able to get more from a smaller, lighter engine and increase fuel efficiency.

Do a test, take a production car, outside any supercar, start than put immediately your car in 4th or 5th gear, and try to accelerate to 100km/h, with a turbo charged engine you will need an eternity, and it is totally normal as you will fall in low rpm when shifting to 5th and the turbo won't be able to kickin and the engine will loose all power. Do the same with non turbocharged. You will see the difference.
Diesel have more torque than gas engine for sure. But generally speaking take two diesel engines of same hp, the one without turbo will have far more torque at low rpm than the other.
Where you can notice this difference is driving in mountain road. If going up in a pass in the Alps, and did it plenty of times with and without turbocharged car, with turbo charged one, you take a turn and miss a shift you are screwed.

But again, everything is depending on the base engine that is turbocharged and the goal to it. Some are good some are not.
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Old 12-18-2016, 06:00 PM   #26
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Turbocharged is the way to go with marine diesels. If you want say 100hp at cruise, you could do it with a 4 liter with a turbo, or a 6 liter without. More parasitic losses with the bigger non-turbo engine. The turbo engine will do the job for less fuel. Pretty much all engines on the market now over 100hp are turbo.

Problem with trawlers is that many engines are spec'd for planing out, and if you are not going to run like that, the turbo and extra engine size is rather pointless. But most of the time you pick a boat and deal with the engine someone else spec'd.

Not many of us get to decide whether the engine has a turbo or not. We buy what we want, and if it has a turbo, then it has a turbo.

When I built my boat I estimated that it would need 250hp to cruise 20kts. I picked an engine rated at 450hp, turbo of course, figuring it would have a happy life at 250hp. So far, so good. Turns out the boat is a little more slippery than estimated, 20kts is about 220hp which I could safely have done with a six liter engine. But it is fun to go fast some times!!

At slow speed the turbo does nothing. The engine there at 8.3 liter is not much different than a 6.6 liter Ford natural.

Whether an engine is turbo or not is WAY down on my list of things to worry about.
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Old 12-18-2016, 06:40 PM   #27
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Mostly found that turbo's add efficiency and power when needed in both cars and trucks in various makes both gas and diesel. Similarly in boats I generally favor the turbo versions as they have always been clean runners and ran great for us.
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Old 12-18-2016, 06:43 PM   #28
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"Do a test, take a production car, outside any supercar, start than put immediately your car in 4th or 5th gear, and try to accelerate to 100km/h, with a turbo charged engine you will need an eternity, and it is totally normal as you will fall in low rpm when shifting to 5th and the turbo won't be able to kickin and the engine will loose all power. Do the same with non turbocharged. You will see the difference"


You could do the same test with various sizes/hp of regular non-turbo gas engine options in the same vehicle. When comparing this test in say a Checy pickup one with a base 6 cyl vs another with a 502 V-8 the same results would happen. Your just seeing the results of power available and the gearing you are forcing onto the experiment.
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Old 12-18-2016, 06:50 PM   #29
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My turbo Jetta had plenty of torque but there was a lag and it was midrange. It was an issue but a very monor one. The midrange power was really strong. My present 5cyl Jetta is 600cc bigger, same power but absolutely flat power curve. Very precictable. Of the two engines In a boat I'd opt for the turbo. For my car definitely the 5cyl non turbo.

In Alaska I was an operator in a powerhouse w a new (almost) 1500hp eight cyl Enterprise engine. This was 1960 and it had a turbo and the big E ran at about 75% load 25% of the time. Very little turbo noise.
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Old 12-18-2016, 06:55 PM   #30
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Wifey B: My turbo car has power at all rpm's. 530 hp or so, 0 to 60 in 3 seconds.
I was about to say....most modern day turbocharged cars have no turbo lag.

To answer the OP, it is all a matter of application...as someone has already said. If you need "power density" there is no better choice than to turbocharge.

My choice in a car would be V8 NA. I just love the roar of an American made V8....like the modern Chevy small blocks. Turbochargers inherently muffle that exhaust note. Some people like that whoosh noise of a turbocharged car. I like the roar.

As it applies to boats...I would prefer NA if I am going slow. Nothing wrong with something like a Lehman 135. But if you want to go on plane in a larger powerboat, you don't have a choice than to go with boost.
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Old 12-18-2016, 07:01 PM   #31
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Wifey B: My turbo car has power at all rpm's. 530 hp or so, 0 to 60 in 3 seconds.
And my educated guess based on performance is a Porsche 911 Turbo?..
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Old 12-18-2016, 07:04 PM   #32
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BandB and Fletcher500 have made the key points. What I would add is, they are used for a reason in industrial/marine applications - namely to reduce the total cost of ownership per horsepower. Hard to argue with that.

Oh, and one other thing... for folks concerned about engine stress and longevity - a lot of horsepower per liter of displacement is 200. not 50.
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Old 12-18-2016, 07:26 PM   #33
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Oh, and one other thing... for folks concerned about engine stress and longevity - a lot of horsepower per liter of displacement is 200. not 50.
I know of no production engine anywhere that makes 200hp per liter??? Porsche probably pushes the hardest....and maybe Mitsubishi.
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Old 12-18-2016, 07:45 PM   #34
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I know of no production engine anywhere that makes 200hp per liter??? Porsche probably pushes the hardest....and maybe Mitsubishi.

Ya 200 is "a lot", and no Porsche doesn't make the top ten. Mitsu does.. Mercedes has one that comes close. 375hp 2 liter. Lots of street tuners go way way beyond 200.

https://en.wikipedia.org/wiki/Mercedes-Benz_CLA-Class
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Old 12-18-2016, 07:50 PM   #35
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And my educated guess based on performance is a Porsche 911 Turbo?..
Wifey B: You win. Now guess Dauntless's fuel. It was always my dream car. Four years old now, about 16,000 miles on it.

Two more questions while at it. Why did they keep reminding us last night that we were watching Thursday Night Football on Saturday Night, and why does the Lazy River Ride at Atlantis not return you to where you started and leave you to walk back. After all, you are lazy.
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Old 12-18-2016, 08:02 PM   #36
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Ya 200 is "a lot", and no Porsche doesn't make the top ten. Mitsu does.. Mercedes has one that comes close. 375hp 2 liter. Lots of street tuners go way way beyond 200.

https://en.wikipedia.org/wiki/Mercedes-Benz_CLA-Class
911 Turbos S is 148hp per liter...in R&T's top 10.

http://www.roadandtrack.com/new-cars...tputs/?slide=9
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Old 12-18-2016, 08:03 PM   #37
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I've owned 4 turbo diesels and 1 naturally aspired. I'll take the turbo most every time. In addition to being more efficient, they also leave more space in the engine room compared to the same HP NA. My Cummins 6CT 300 HP runs at 70 to 80% for hours on end. Have over 5,000 hours on the rebuild (bought used) and it still has perfect oil analysis. Change the oil regularly and cool them down for a minute or two before turning them off, is the key to long life.

Have the Cummins 6BT 220 HP in my 2002 Dodge pickup. With 425,000+ miles, it shows no signs of wear. Unfortunately, finding parts for the rest of the truck is starting to get challenging.

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Old 12-18-2016, 08:08 PM   #38
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In addition to being more efficient, they also leave more space in the engine room compared to the same HP NA.
And in a sport or performance boat, they allow you to have a more powerful engine. That's also why you see those boats with MAN engines and not CAT's. Size and weight are critical.
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Old 12-18-2016, 08:33 PM   #39
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Several have mentioned the efficiency of a turbo being better than NA. Can someone site some examples or documentation. I'm very skeptical on this.

HP is needed to drive the turbo, and I'm hard pressed to believe that the output makes it more efficient.
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Old 12-18-2016, 08:51 PM   #40
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Several have mentioned the efficiency of a turbo being better than NA. Can someone site some examples or documentation. I'm very skeptical on this.

HP is needed to drive the turbo, and I'm hard pressed to believe that the output makes it more efficient.
Ok, consider parasitic drag. A 4 cylinder turbo diesel producing the same HP as a 6 cylinder non turbo diesel. Driving those 2 extra cylinders requires HP.

For planing hulls, the larger heavier non turbo engine has a penalty in weight to make the boat plane at the same speed.

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