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Is This the "Day of the Diesel?"
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On one hand, you are correct -- it's the gearing and final-drive ratio that determine engine speed at a given speed and gear.
On the other hand, the gearing and the final drive ratios used in the design are selected based in part on the torque generated by the engines. So it is reasonable to expect a diesel to cruise at a lower engine speed than would a comparable gas engine. It's not the difference cited by Gagrice (who does have a persistent tendency to make up a fair bit of his "data" as he goes along), but there should be a modest difference.
The difference is quite simple. When pulling a long grade, which was my premise for liking to drive the diesel Passat, the Camry or other gasser/hybrid cars would have to downshift to maintain the same speed. The 4 cylinder gas engines in the midsized cars are not well suited to heavy loads. Put 4 adults in a new Camry 4 cylinder and take a drive up a long grade on one of our Interstate highways. It is a chore for that little gasser to maintain even the 75 MPH speed limit. They do go like blazes downhill.
As you have pointed out it is all a matter of gearing. I think my point was lost in the RPM argument. Diesel engines by their lower RPM average have a longevity advantage over a gas engine.
I think one reason people buy new cars is because their old cars don't have new (cool) stuff in them.
Another is that it takes a certain "type of person" to want to keep a car for 250,000+ miles. Not everyone thinks that is a worthy goal or a good thing to do.
There is more to owning a car than have an engine that can theoretically make 250,000 miles. Cars that approach that many miles inevitably have a lot of things broken. Small plastic interior pieces that have broken. A power window motor stops working. A transmission goes out. The ABS system has a problem. There's a gouge in the rear bumper from that little pole you didn't see when backing up at the county fair. Seats rip. Carpets need replacing. Keeping all that stuff in perfect running order can sometimes be very costly.
My point is that although you might have a diesel ( or a SAAB gasser ) engine car which hits 1 million miles, the cost of maintaining items other than the engine will be high without fail.
That's another perfectly good reason people trade cars: If it's going to cost $1,500 to get the fuel injector or the air compressor replaced/repaired, why not just trade the car in and use the $1,500 on the down payment and get a whole new car out of the deal?
If diesel engine cars were built with other parts and components equal to the longevity of the engine itself, well, there would be no better cars made anywhere. Too bad that's not true.
It was true at one time. There are still many MB diesels from the 1980s running fine with all their amenities working. Our 1990 LS400 runs great. Too bad the new Lexus and Mercedes are not as well built as the old ones. It is the toys and gadgets and electronic wizardry that has degraded the longevity of our cars.
I think one reason people buy new cars is because their old cars don't have new (cool) stuff in them.
Another is that it takes a certain "type of person" to want to keep a car for 250,000+ miles. Not everyone thinks that is a worthy goal or a good thing to do.
There is more to owning a car than have an engine that can theoretically make 250,000 miles. Cars that approach that many miles inevitably have a lot of things broken. Small plastic interior pieces that have broken. A power window motor stops working. A transmission goes out. The ABS system has a problem. There's a gouge in the rear bumper from that little pole you didn't see when backing up at the county fair. Seats rip. Carpets need replacing. Keeping all that stuff in perfect running order can sometimes be very costly.
My point is that although you might have a diesel ( or a SAAB gasser ) engine car which hits 1 million miles, the cost of maintaining items other than the engine will be high without fail.
That's another perfectly good reason people trade cars: If it's going to cost $1,500 to get the fuel injector or the air compressor replaced/repaired, why not just trade the car in and use the $1,500 on the down payment and get a whole new car out of the deal?
If diesel engine cars were built with other parts and components equal to the longevity of the engine itself, well, there would be no better cars made anywhere. Too bad that's not true. "
Indeed thank you for asking the question and thank you for going on to give examples of my point.
I have met and do know race drivers. Good judgement in life choices are not their strong suit. By necessity they all think they are immortal.
In real life the 99.999% of the rest of us understand things far differently.
Again it was like a needle in a haystack finding out the design parameter for the VW TDI engine of 25,000 hours (@ average of 50 mph). I It is probably even scarcer to find what the (hours)design parameters are for the Honda 4 banger.
Incidently, (off topic)the goal for mine Civic gasser is 250,000 miles and above. I am doing 20,000 mile OCI's with Mobil One 0w20,5w20. I also understand that the Mobil One 0w40 gives even more excellent oil analysis numbers.
'11 GMC Sierra 1500; '98 Alfa 156 2.0TS; '08 Maser QP; '67 Coronet R/T; '13 Fiat 500c; '20 S90 T6; '22 MB Sprinter 2500 4x4 diesel; '97 Suzuki R Wagon; '96 Opel Astra; '11 Mini Cooper S
Can we just forget about it now?
'11 GMC Sierra 1500; '98 Alfa 156 2.0TS; '08 Maser QP; '67 Coronet R/T; '13 Fiat 500c; '20 S90 T6; '22 MB Sprinter 2500 4x4 diesel; '97 Suzuki R Wagon; '96 Opel Astra; '11 Mini Cooper S
In #148, you claimed, "The biggest advantage you two have with the TDI is while you are cruising at 1500 RPMs the guy next to you in his Camry 4 cylinder is turning about 2800 RPM."
According to this test of the Jetta TDi in Canadian Driver, the Jetta is turning 2,500 rpm in top gear at 120 km/h (75 mph).
According to Car and Driver, the Camry SE's top gear is set at 26.3 mph per 1,000 rpm. At 75 mph, that equates to 2,811 rpm.
That's a difference of 300 rpm, not 1,300 rpm. At 60 mph, the difference would be about 250 rpm. This is not even close to what you stated earlier.
I would hope so -- even with a turbo, the Jetta TDi is a much slower, less powerful car:
Jetta TDi: 100 hp, 0-60 mph in 11.5 seconds
Camry SE: 158 hp, 0-60 mph in 8.6 seconds
I've surpassed the 300,000 mile mark. Twice. In a 16-year span. With the same car - a 1987 VW Golf GT. It would have gone further, except that it met its demise at the 624K mark during a 55 mph encounter with Bambi. I performed most of the maintenance on the car (oil/filter changes, spark plug changes, timing belt changes, water pump, brake rebuild, A/C rebuild, suspension changes, exhaust changes, alternator change, starter change, and a fuel pump replacement). The only maintenance items I didn't perform required putting the car on a lift (clutch, drive axles, front wheel bearings, engine/transmission change at the 429,000 mile mark).
I replaced it with a 1997 VW Vento (Jetta) and just turned over 200,000 this evening. With my 1hr, 20 minute daily commute, I should hit the 300,000 mile mark in about 3 years... :shades:
On a practical basis, while it is VERY obvious 11.5 seconds is slower than 8.6 seconds, it is really not a big deal, especially on the open road. As a comparison, I am also keeping in mind a 4 sec 0-60 car that I also have.
Also, the diesel fans have a tendency to give credit to the diesel that they should be giving to the turbocharger that is often attached to diesel engines. Diesels need forced induction just to get even tolerable performance, as the Jetta illustrates -- 100 horsepower from 1.9 liters AND a turbo is pretty lackluster at best as compared to a gas engine with a turbo. The VW Audi 2.0 liter turbo gas engine produces about 200 horsepower, about double the output from a turbo engine of about the same size.
The turbo is an intergral part of the design. So what about the T in TDI, is not giving credit to the turbo?
I notice a tendency in these discussions for apples-to-oranges comparisons being made between turbodiesels and normally aspirated gas engines, while forgetting that a turbo gas motor will generally far exceed the performance of a turbodiesel of similar size. If you want to measure the true benefits and deficiencies of diesels, you need to start by accounting for what is being contributed by the turbo, which provides similar benefits to both types of engines.
I think that you can safely make these general statements when comparing a turbocharged gas engine and turbocharged diesel of similar displacement and configuration:
-The diesel will have less horsepower
-The diesel will have slower acceleration
-The diesel will have a lower top speed
-The diesel will rev less freely, and redline at a lower point
-The diesel will have better fuel economy for a gallon/liter of fuel
You can argue about what matters most to you, but at least let's be honest about the benefits and drawbacks of each. And let's also acknowledge that installing turbos on gas engine will provide a portion of that same benefit to gas engines that it does to diesels.
NO! I am not. That is YOUR interpretion, even after I have mentioned at least twice about TDI turbo diesel. So I am not sure what you are trying to prove!?
...""The diesel will have less horsepower
-The diesel will have slower acceleration
-The diesel will have a lower top speed
-The diesel will rev less freely, and redline at a lower point
-The diesel will have better fuel economy for a gallon/liter of fuel "...
Not sure why you are trying to reinvent the diesel/turbo diesel here!!???
You are being way redundant again. If you wish to do that go ahead, I will just stop answering.
That's sidestepping my point, which was to point out the flaws of comparing a normally aspirated gas engine to a turbocharged diesel.
The comparison was made for SIMILAR torque 161 vs 155.
Again, I don't understand the point of mentioning torque, when it has no discernable benefit to acceleration, as has been implied here. Higher torque numbers in a vacuum don't help passenger cars to achieve better acceleration, so why keep bringing it up as if it does?
the Camry was the bigger 2.4 vs the 1.9 TDI. and the almost extreme difference in mpg.
This is the sort of apples-to--oranges comparison that I'm talking about. Is anyone actually surprised that a motor with 50% more output and stronger acceleration in a larger car gets worse fuel economy? I would expect to see this very same thing with any comparison you could make, including one that included only diesels.
I will grant you that diesels get better fuel economy. But you overstate the differences by comparing cars that aren't similar to each other.
Force = force? like for like (relatively) 161 # ft of torque vs 155# ft of torque!!?
Horsepower. http://en.wikipedia.org/wiki/Horsepower
Have you ever compared similar cars in turbodiesel and turbo gas variants to see the difference? You'll invariably find that the diesel gets better fuel economy, but is slower. The torque doesn't help the diesel cars to achieve better acceleration.
I'm not talking about what's important to me, I'm just trying to get the discussion to stay honest and not prone to overstatement.
Again, why do you keep mentioning torque as if it is a substitute for horsepower when there are plenty of high torque engines that deliver slower acceleration? Torque clearly isn't where it's at -- the cars are slower.
You only achieve these numbers by comparing cars that aren't evenly matched, and then overstating the benefits of the diesel. That's not a legit course of argument for the diesel fans to take.
So if you compare a 1.8T VW to a 1.8T VW now thats evenly matched eh? 31 mpg=31 mpg? You want an endless loop? Just talk to yourself.