Have you driven a modern diesel? At lower speeds, they easily beat similar-displacement petrol cars off the line with superior torque. They are weaker at high speeds, but in normal (especially city) driving, a diesel is usually faster than a petrol.
But yeah, their main factor for popularity is the cost per km. They use less fuel than petrol engines, and the fuel is less expensive (in Germany). This is offset by higher road tax and insurance somewhat, but for commuters and others who drive a lot (>~20000km per year) diesels are a much more cost effective option in Germany than anything else.
Diesel isn’t that cost efficient actually, even if you drive a lot. Diesel are more expensive to maintain due to regulations, plus diesel cars tend to be more expensive their petrol counterparts. Moreover, there is depreciation, which tend to be worse for diesel cars, because they are valued less on the second hand market (fairly or unfairly).
On average, you should expect to drive at least 150.000+ km before you’ve broken even on a diesel car with its petrol counterpart.
People only look at fuel consumption and fuel prices, but maintenance and depreciation are actually one’s biggest loss on a car purchase. And in general petrol comes out on top.
The premium of diesel engines over petrol is one of the key reasons that we don’t get many in the USA (the other issue being emissions). Bob Lutz, former GM CEO, was a big proponent of diesel but repeatedly acknowledged that it doesn’t make sense in the USA. The market for people willing to pay the $5,000 premium (in 2007 dollars, mind you) was very small. Americans don’t appreciate just how cheap cars in their region are.
GM did manage to get a diesel Cruze into the USDM market, and keep it here, but it’s low-margin and not a huge seller. A manual diesel Cruze starts at about $25,000 (compared to $17,000 for the base). So it is basically slotted as an «enthusiast» model, just not a high-performance one like Ford and Honda would offer.
Different tax systems can affect the equation even if you disregard that you pay less at the pump for fuel that your car consumes less than a petrol equivalent – lower CO2 figures may also mean that you pay less yearly fees or less taxes on car registration as well. The break-even figure certainly varies by country (as does depreciation of different cars).
Diesel has a higher maintenance cost too, especially if you only drive short distances. IIRC the main cost here is the catalysator, which basically clogs up if it can’t properly heat up. That doesn’t happen on short range.
No, that only applies to cars with the more fancy antiparticulate filter that also requires urea fluid.
No, this has nothing to do with urea fluid. This is just a quirk of some DPFs.
> Now Germany spews out about same carbon as before giant investments in solar, electricity is four times the price as in US, plus they now have to buy from France cause they don’t produce enough.
Well, they require a more complex motor which handles higher pressures and supercharging. The picture would be different if you would compare motors with the same price.
It’s an illusion that diesel vehicles are faster than gasoline. Gasoline engines have way more horsepower and are faster that the diesel options (unless Germans are getting neutered or smaller power plants than say, the USA)
That’s a strange statement. More horsepower based on what? I think if you look around, you’ll see that the largest and highest horsepower combustion engines all burn diesel. Semi-trailers are exclusively diesel.
Your statement on speed is also odd. Record setting cars may burn gas, but your typical car driving around a city or highway needn’t ever go faster than 160km/h. Most cars can achieve this, and most modern cars, whether diesel or gas, can achieve this without much difficulty.
This leaves us with acceleration, where diesel vs gas is equally unclear. As small diesel engines often ship with turbos, you’d be perhaps comparing a turbocharged 2.0L diesel vs a normally aspirated 2.0L gas engine. Assuming roughly equivalent mass of the cars, with higher low-end torque, the diesel will win just about any street race.
If what you’re comparing is purchase price to acceleration, then indeed the gas cars may win.
> the diesel will win just about any street race.
This is really wrong. It’s a weird myth that gets perpetuated in America where people don’t really drive diesels.
Let’s compare a 2.0L diesel Golf TDI to a 2.0L petrol Golf GTI. Same car, same displacement, both turbo engines.
The Golf TDI does 0-60 in 9.0s and a quarter mile of 17.0s@84 mph.
The Golf GTI does 0-60 in 5.7s and a quarter mile of 14.2s@100 mph.
There’s a staggering difference in performance there. The TDI is so slow that it’s genuinely difficult to find a Motor Trend instrument test on a slower car, because at that point, it’s too slow to really bother.
I found the 2018 Rav4: 0-60 in 9.3s and a quarter mile of 17.0@82.
If you want to do this comparison please do it right: The Diesel equivalent to the Golf GTI is the Golf GTD. There’s more than just displacement that makes up an engine and the fact that is some kind of turbocharger.
Their difference in 0-60 seems to be 6.4s vs 7.4s according to what I find. Guess the difference in higher regions might be even less, because of a different torque profile in turbocharged diesel engines.
The GTD is Euro-only, so it’s harder to get performance comparisons. But it’s still much slower than the GTI, I found a 15.6@93 in the quarter.
0-60 is an awful way to measure acceleration; most of what it measures in modern cars is traction, since a Mk7 GTI will shred the front tires with a hard launch. So high five second and low six second times are both accurate, it just depends how good the launch was.
That’s why you compare quarter mile times when looking at acceleration. And the GTI is still so much faster than the GTD; a full second and a half and 7mph trap. Meaning, in a drag race, the GTD wouldn’t be close enough to read the GTI’s license plate.
I think the 0-40 profile would be much more favorable to the TDI, and much more useful to the typical driver. But we’ll never really know as that’s not the standard measurement.
The diesel golf is still a lot slower to 40 than the GTI. The TDI diesel has a lot of turbo lag, a narrow powerband, and poor gearing. What people who’ve never owned diesel cars fail to realize is, that peak torque number is hugely misleading. It sounds impressive, but it starts from like 2200RPMs and falls off a cliff past 3500. While a (modern) turbocharged petrol engine has full torque by ~1800rpms and that lasts until like 5000rpms.
I’ve owned a (Jetta) TDI before, I even tried to make it fast. Even with a tune and full exhaust it was slower than a stock turbo petrol.
It’s always Americans that talk about how awesome diesels are. I never see posts from Europeans (who are the ones that actually have to drive them) talking up diesels. They are always complaining about how terrible they are.
Diesels are great for trucks, but not cars.
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Tuto diskuzi hrdě sponzoruje:
Registrovaní uživatelé
Založen: Feb 2014
Diesel slow to accelerate?
I’ve got a 4JH2TE Yanmar in my Hylas 46, probably 4600 hours. It seems now slow to speed up, when I advance the throttle lever. Symptomatic of ?
Registrovaní uživatelé
Založen: Apr 2014
Boat: Beneteau Oceanis 45
Re: diesel slow to accelerate?
That’s a classic symptom of a turbo problem. Is it slow to rev in neutral, or in gear or both? The turbo could just be carboned up and a cleaning would fix it, it could be a leak on exhaust or pressure side, or the bearings could be going bad. I don’t have experience with that exact turbo so some else may have more specific advice. Your symptoms definitely point toward a turbo issue.
Or you could have a majorly fouled prop or a rope around the shaft, but my money is on the turbo.
Registrovaní uživatelé
Připojit Datum: červen 2012
Location: Elmvale, Ontario
Boat: Ontario32
Re: diesel slow to accelerate?
Your engine may also be suffering from a blocked fuel filter restricting fuel flow.
Registrovaní uživatelé
Založen: Apr 2014
Boat: Beneteau Oceanis 45
Re: diesel slow to accelerate?
Původně odeslal Crew of Turning
Your engine may also be suffering from a blocked fuel filter restricting fuel flow.
Good point. I was assuming regular maintenance has been done, but that could be a bad assumption.
Registrovaní uživatelé
Založen: Feb 2010
Location: East shore Mobile Bay AL
Boat: ODAY 28
Re: diesel slow to accelerate?
I think I would first look at the fuel filters first,
Registrovaní uživatelé
Založen: Feb 2012
Location: Toronto/Europe
Boat: Cabo Rico NE 400
Re: diesel slow to accelerate?
Could be filters . make sure you check primary and secondary!
Hodně štěstí
Založen: Jan 2012
Location: Pangaea
Příspěvky: 10,856
Re: diesel slow to accelerate?
First check your prop and bottom for marine growth. After you are sure of no growth, then look for other fuel or turbo related issues.
Our boat grew a three inch fur coat of marine growth in just three weeks of staying in one place.
Registrovaní uživatelé
Založen: Apr 2016
Re: diesel slow to accelerate?
I would also look to the air supply and make sure that their is not restricted by not just filter but air intake to the machinery space.
Registrovaní uživatelé
Založen: Feb 2012
Location: Toronto/Europe
Boat: Cabo Rico NE 400
Re: diesel slow to accelerate?
A question we have not asked . do you mean the BOAT is slow to speed up or the actual ENGINE is slow to speed up?
Založen: Feb 2011
Místo: SF Bay Area
Boat: Islander 34
Příspěvky: 5,486
Re: diesel slow to accelerate?
Check the discharge elbow for carbon buildup. That can cause a diesel not to rev.
Registrovaní uživatelé
Datum připojení: prosinec 2008
Místo: SC
Loď: Žádná, postavte tu zobrazenou ze skla, měla mnoho od 6′ do 48′.
Příspěvky: 10,208
Re: diesel slow to accelerate?
Původně odeslal SteveInMD
Good point. I was assuming regular maintenance has been done, but that could be a bad assumption.
I made the assumption you had the boat and this became a problem until this.
Diesels by nature are not going jump up like a gas engine, are you sure you have a problem?
Registrovaní uživatelé
Založen: Oct 2015
Location: Summerstown Ontario Canada
Re: diesel slow to accelerate?
Původně odeslal briblack
I’ve got a 4JH2TE Yanmar in my Hylas 46, probably 4600 hours. It seems now slow to speed up, when I advance the throttle lever. Symptomatic of ?
I would check the static things first. push your throttle to the full throttle position then go and check on the engine to see that the full throttle is opening the injection pump to full throttle. Then bring the throttle back to low. Check your log to see when the filters were serviced last. If in doubt change the secondary. if your primary only a fuel/water separator? Then start the motor up and increase throttle and take a stetescope to listen to the turbo winding up. You can usually tell if the revs go to maximum. Then go for a ride and see how the engine performs under load. Let us know what you find. Roger
Založen: Jan 2012
Location: Pangaea
Příspěvky: 10,856
Re: diesel slow to accelerate?
My bet is still on marine growth, it doesn’t have to be significant to make a big difference.
Registrovaní uživatelé
Připojit Datum: srpen 2010
Location: Longboat Key, FL, USA
Boat: 1988 Hunter Legend 35
Re: Diesel slow to accelerate?
Have to say it could be any of the above but without some more info it’s almost impossible to say:
— Slow to rev or slow to move ? (ie. what happens without prop engaged?)
Answer that and we can start looking at whether it’s a fuel/engine/prop/hull problem
although I have to say my first question will always be:
— when did you last have the hull/prop cleaned, if I don’t clean my hull (mid atlantic coast) every 1-2 weeks she feels like a slug when trying to move
Registrovaní uživatelé
Založen: Apr 2014
Boat: Beneteau Oceanis 45
Re: Diesel slow to accelerate?
That’s a lot of options! Let’s see if we can help narrow it down a bit. Here’s what I am thinking.
Unless you have a filter vacuum gauge, it might be time to do a filter change, especially if you have been in rough water recently since that can stir up tank sediment. However a clogged filter is most likely to first start showing problems under high fuel use condition such as motoring near hull speed. A filter vacuum gauge will eliminate the guess work on filter condition.
Diesel engines generally don’t accelerate as well as gasoline engines, especially older diesels. The turbo greatly improves diesel acceleration. That’s why most diesel cars are turbocharged. If your turbo is not working properly acceleration will if poor, even under low load situations (like in neutral). If the engine wont accelerate (rev) well in neutral it is not bottom growth or prop causing the issue. Also if revving in neutral is a problem it’s likely not a filter issue because it’s not a high fuel use situation (unless the filters are almost totally blocked). More info on the acceleration problem would be helpful. Revving the engine to near max rated rpm in neutral to test this is not bad for your engine.
You can test the idea of lack of air by temporarily removing the filter if it has one and opening the engine compartment while the engine is running to see if that improves the problem. Many marine engines only have a screen and not a filter. Usually there is not much dust in a marine environment.
It could be a clogged exhaust elbow. Often, but not always, you will have reduced cooling water flow with a clogged elbow. How does the cooling water flow look? Normal? Low flow would be a sign it’s the elbow. Also, if you have not done it in the last year or two, it is time for the elbow to be removed and inspected. They often will develop cracks when they get old which can leak exhaust in to to cabin.
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