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While it may be true that the "CONE & BELT" type of CVT can slip when pushed to the limit, that is not the case for the "PLANETARY" type.
Stop spreading the misconception that there is only 1 type of CVT. There are 2. And the stronger used in "full" hybrids, PLANETARY, is indeed capable of handling a lot of power or torque.
JOHN
Replying to: falconone (Nov 07, 2005 9:37 am)
Just about all the makers you have mentioned in European markets for example; fully have 45% of the passenger vehicle fleet (and more and growing) with diesel options. While CVT's might be catching on, the majority of transmissions in those markets are manuals.
I think also one can say the DSG or the computer controlled manual shifter is catching on.
But truly I think a "CVT" type might have more widespread appeal here; simply because the USA market is the majority of automatic transmissions. So the transition might be considered seamless. So in the USA one can pine on about saving fuel, but doesn't really have to do it.
"Here's a summary: Diesel engines go farther on a gallon of fuel than standard gasoline engines because of their design, and because of the higher energy density of a gallon of diesel fuel. But it takes more oil to manufacture a gallon of diesel than a gallon of standard gasoline, and the production and refining processes for diesel produce more heat- trapping gases. So when you're considering the relative merits of diesel and non-diesel cars (like your friend's VW and your regular alternative), UCS suggests knocking the mpg estimates for the diesel car down by 20 percent to account for those impacts. Since a diesel vehicle will also cost you more, you'll get more bang for your buck from an efficient gasoline car if you're concerned about fending off global warming, UCS says.
And the nasty rumors about diesel are true: It's less refined than gasoline, aka dirtier. Diesel cars emit substantially more particulate matter and NOx, both of which are serious air pollutants and health hazards. Current passenger diesel engines are more polluting per mile driven than gasoline models. And no diesels currently make it into the American Council for an Energy-Efficient Economy's Green Book."
So until diesel gets cleaner and the technology for filtering exhaust improves, no one can buy a new diesel and truly have a clean conscience about it.
If you want a clean, high MPG vehicle, go with a Hybrid.
-juice
You left out the above sentence in that article. A diesel using B100 is less polluting, especially with the "ZERO" CO2, than the hybrids. You act like it is the responsibility of each individual to formulate the quality of the fuel they burn. I don't know how anyone can use the dirty gas sold in 45 of the 50 states with a clear conscious. Personally I burn the cleanest ULSD I can buy while in CA. If I travel to AZ or other states it is not available. Not my fault.
As far as B100: How many people can get B100 for every fillup? I'd bet not a large percent of Americans can drive locally to a B100 pump.
It's not the responsibility of any commuter to "formulate the quality of the fuel they drive" unless they are making BioDiesel in their backyard, I guess !!
But if you have a choice between car A at 45 MPG (dirty) and car B at 45 MPG (clean) the choice should be clear.
This has been and continues to be particularly short sighted.
I would agree with Gagrice "not my fault" The ones that should be pinged are the regulators who did not make the (lower sulfur) diesel switch at the same time in the late 70's as the switch to unleaded fuel. If they had made the switch we'd have a lot more of the PVF using alternative fuel/s. Write and thank your legislatures and governments for this oversight.
-juice
I guess "short sighted" can also mean "100% true."
Learn something new every day....
And the nasty rumors about diesel are true: It's less refined than gasoline, aka dirtier.
These 2 statements contradict each other completely.
The 295 lb-ft torque @ 0-1200 rpm isn't the slightest bit of a problem for the 50kW motor in Prius. The 123kW motor in Highlander-Hybrid is even more powerful, yet it doesn't hasn't ever destroyed a CVT either.
I'm tired of this misleading. Those vague claims about diesel torque simply do not apply.
JOHN
Now, if you're talking about the sheer amount of torque, then that may be an issue.
But look at the Prius - look how much torque it makes at zero rpm. Yet it has a CVT.
It's probably because it doesn't have to sustain that amount of torque for an extended period of time.
-juice
Also last I checked, the Prius engine is still an internal combustible engine!!?? I'd make a comment about a past post about how the Prius "Stuff" doesnt stink (but the passing of ... gives it away) , but the host will step in.
The Prius' electric motor makes it's greatest torque at zero rpm, and then it falls off fairly quickly, I believe to 1200 rpm. Electric motors are know for their low end torque but the demand on power to produce that torque is large. The closest example I can give is the motor in an air conditioner. It may draw 13 amps while running, but can draw up to 20+ amps for a bunch of seconds when starting.
Or perhaps the most telling item: a hybrid was NOT entered.
But that's precisely when the Prius is using max torque from the electric motor to get underway. John - what is peak torque again? 400+ lb-ft?
CVTs usually have a very wide range of gearing to compensate for that, i.e. gearing range reaches both shorter and lower gears than most conventional trannies.
-juice
But that's precisely when the Prius is using max torque from the electric motor to get underway. John - what is peak torque again? 400+ lb-ft?
CVTs usually have a very wide range of gearing to compensate for that, i.e. gearing range reaches both shorter and lower gears than most conventional trannies. "
-juice
Right, that indeed might(actually has proven to) be what it takes on a practice technical specification level to deal with the "off the line" conditons and etc and safety factor!!
However, the real question: is that usable torque over the entire band width of operation? I think you and I and or folks who have looked at the Prius indepth know the answer to that!?
So for example with 400 # ft of torque (on a diesel) I have a certified 1000 mile, at 100 plus mph, autobahn MONSTER cruiser. vs a ...Prius... ?!
But the truth is I have that now in a 90 hp (lower than my Honda Civic VP horse power)with 155# ft of torque and still can go 1000 miles at autobahn speeds and with 48 mpg!!!???
Name one, other than torque. Other than startup torque, diesels are advantageous only when you are cruising at higher speeds and want good economy at cruising speeds.
The DARPA race was run across the desert, so I doubt "good high speed fuel economy" was a factor at all. In fact, I was correct - average speed was 19.1 MPH, so diesel had no advantage other than possibly torque.
"The first four finishers entered the history books as the first ground vehicle robots to complete such a demanding course in under 10 hours. Stanley averaged 19.1 mph over the course."
P.S.
SO There WAS a Hybrid in the competition. Finishing behind the Stanford and Carnegie Mellon vehicles were a customized Hummer and a Ford Escape Hybrid."
http://www.internetnews.com/ent-news/article.php/3555151
I have take a portion of an article from Angry Engineer, dated December 2004.
Will Diesels Spell The End For Parallel Hybrid Drivetrains?
It seems that in the past few months, there has been an increasing amount of information coming out about the development of diesel-electric hybrids by certain OEMs. This indeed is a logical development, as the primary purpose of hybrid technology is to conserve energy (whether they do so or not is the topic of another post), and without a doubt, a properly-utilized diesel offers an advantage over spark-ignition internal combustion engines through two primary means - an increased compression (and thus, expansion) ratio, and the elimination of pumping losses across the throttle plate (reduced by some extent by lean-burn, cylinder-deactivation, and fully-variable valve lift technologies, but never quite eliminated).
Many future hybrid designs depend on the use of a CVT transmission to keep the engine working at a point where the engine can develop the required power (a combination of the power required by the dynamics of the vehicle itself plus the desired amount of energy to be stored in the reserve mechanism). Sure, it's possible to use a stepped-ratio transmission in this application, but hybrids require optimization of, well, damn near every aspect of the powertrain in order to provide a usable improvement in economy. CVTs also provide a wide ratio spread in a small package, which is additionally important in a hybrid due to the added packaging volume that the electric drive brings with it. One can see that a CVT is simply the right transmission for the job.
But CVTs bring with them one major drawback, and that is a lack of torque capacity. 300 Newton-meters (221 ft-lbs) of torque capacity is considered by many to be the current benchmark, and at that, they are not suitable for use even with many of the smaller highly-turbocharged four-cylinder diesels, much less one of the larger diesel engines one might expect to find in future large-car and light-truck hybrid applications. Quite simply, the diesel's high cylinder pressures and low operating speeds are going to result in a significant amount of torque in order to meet the average customer's requirements for average (and to a lesser extent in hybrids, instantaneous) power output.
But the use of diesel-electric hybrid drivetrains in applications such as locomotives and off-highway trucks has been going on for 50+ years at this point, due to the need to generate a huge amount of torque at a standstill, and the inability to develop a multi-ratio transmission and clutch or torque converter that will accomplish this task efficiently. The solution? Simple - a series hybrid drivetrain, where in the engine is only connected to the drive wheels through the generation and energy-storage mechanisms.
This completely eliminates the need for any transmission, and indeed, taken to the logical extreme, eliminates the needs for a drivetrain if the electric motors are simply mounted at the wheels. Doing so brings about its own problems (an potential increase in unsprung weight, for one), but there would be obvious advantages to eliminating the mass and packaging volume requirements that come with traditional drivetrains - the elimination of distinct vehicle platforms and all the restrictions they bring to new designs would be a start. In all likelihood, a series system would be less complicated than a parallel system (remember, we've been building locomotives and dump trucks like this for a long time), and it probably brings additional efficiency to the table as well.
Of all the good reasons we have to build series hybrids, it just might end up that we go in that direction due to the lowly torque-handling capabilities of the CVT, a problem that's as old as the CVT itself (going right back to the days of Van Doorne). Or, hey, maybe someone will decide that something like hydrostatic drive is really the way to go and the parallel architecture will live on for another few model cycles, allowing the current OEMs to become even more firmly entrenched in their current thinking and manufacturing capabilities.
Base Engine Type: Inline 4
Horsepower: 110 hp
Max Horsepower: 5000 rpm
Torque: 82 ft-lbs.
Max Torque: 4200 rpm Drive Type: FWD
"...
2005 Toyota Prius
Even Toyota and Honda produce diesels, and have for a long while. (in addition to be two of the first to market hybrids.
In terms of diesel? At 19.1 mph (avg speed)it hardly meets your assertion of working only at higher speed/s!? All the normal attibutes; i.e., durable, longer range, longer time at idle capability, you addressed torque, low (@idle) fuel draw, etc.
Like I said, a gasser VW Touareg could have just as easily been chosen.
However, the real question: is that usable torque over the entire band width of operation? I think you and I and or folks who have looked at the Prius indepth know the answer to that!?
As a Prius owner, I'll answer this.
It's sort of usable.
While a lot of the priusphiles like to talk about 295lb ft of torque, they do neglect to mention the fact that the Prius transmission must be hella lossy, much more so than a regular transmission/cvt'ed car, because it sure as heck doesn't feel like a regular car with 295 lb/ft of torque. I'd probably say about 1/3 of that makes it to the wheels, which is somewhat understandable given the nature of the transmission.
The power is there, especially with a full battery. Conversely, with an empty battery, you really want to be careful how you merge into traffic.
This is one of the reasons why I advocated putting the Prius on the dyno. If it is your SOTP experience that 1/3 of the hp makes it to the wheels, that is now a 66.67% LOSS!!
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I would agree! That is also my SOTP experiences also. (Limited to app 300 total miles in one day)
I have nearly 30,000 total miles in my Prius, tho over almost 2 years.
Is it underpowered? Sort of, yeah. Will most people notice? Sort of, yeah. Would a dyno run show a 66% drivetrain loss...
Yeah, I think it's just about that. I seem to recall a guy on PC who put his Prius up on a dyno, and I think it might have cracked 100 lb/ft at the wheels, but not much more than that.
1. Too much torque will/could lead to vehicle control issues, especially on front wheel drive.
2. Too much throttle from a standstill = large demand of power from the battery pack, thus decreasing useful range.
3. Preserve the CVT and the rest of the drivetrain from being eaten alive by so much torque.
As to your Subaru WRX, I have read a number of articles confirming your experience. That engine produces no power until you flog it. A five or six speed manual definitely belongs on the business end of that engine.
Nice friendly green vehicle leaving smoking black streaks on acceleration. Nice picture.
The tires are the problem, not the vehicle or the torque.
self-righteousness is not necessarily a factor for everyone's car purchase decisions, although it appears to be a factor for you and maybe for many hybrid drivers!
hey, if diesel prices keep up the way they are, there won't be any increase in the % of diesels in the US fleet, so don't worry about that too much you sports-car-hatin/diesel-hatin hybrid drivers!!!!
I don't hate any car. I love hybrids because of what they stand for, what they do, and how much money mine saves me every month in fuel costs. I went 31 days between fillups last tank.
I've owned sports cars, and for a certain time in your life, everyone SHOULD own a fast car, just to get that sort of thing out of their system. I had an Infiniti Q45 that would accelerate like a Porsche, and I loved that feeling, but it was very wasteful.
If I lived in an area where B100 or ULSD was available readily, and my commute was 100 miles per day on the highway, I would CERTAINLY consider a diesel car, but I really do hope in the years to come they become legal in all states and the technology improves to reduce to the soot emissions.
If someone built a diesel/electric hybrid 5-passenger car that got 70 MPG on the highway, I would buy one today.
I believe the torque is 295 but due to the nature of the CVT, the TRAC cuts in when too much torque (throttle) is applied.
If that were the case, you'd see the TRAC icon a lot. The only time I ever see it is during the rain.
My old Jetta, which had less than 2/3 the torque of the Prius (supposedly) would trigger the traction if I pushed the pedal to the floor on acceleration.
The Prius, it's a good car. But after 30K miles I can assure you it's not anything close to 'fast'.
2004 Prius 1/4 mile ET 17.7 MPH 79.0
2004 Jetta GLS TDI ET 14.5 MPH 100.45
Prius and Jetta TDI are both optimized for economy, not speed. There are diesel sports cars (not in USA, yet;) and in the future there will surely be hybrid sports cars.
Cost, emissions, fuel economy, renewable fuel vs. petroleum fuel use, there are plenty of more constructive areas to discuss than 0-?.
2004 Jetta GLS TDI ET 14.5 MPH 100.45 "
I had mentioned in prior posts how the hybrid advocates couch their SOTP experiences with make believe math.
So all together now: ET's of 17.7 seconds ARE FASTER than ET's of 14.5 seconds!! AND 79 mph IS faster than 100.45 mph. Paying 7,346.00 more IS cheaper than paying 7346.00 LESS.