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#31
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In article .com>,
wrote: >This mans got a point here. Autos slush boxes are real gas guzzlers. On my previous car, a 1991 Mercedes 280E with a straight six engine, the petrol consumption figures for an automatic were lower than for a manual transmission. >They aught to be banned from being sold. If you are too lazy to shift >gears, THAN DON'T DRIVE! Stay off the road!!! I don't want some lazy >dork with the slush box driving near me. Such idiot drivers are lazy >and inattentive. > > > ><<<<When I converted my car from auto to manual, the mileage >improved by 15% immediately. Also, for motorway driving, >overdrive in the auto was a longer ratio than 5th in >the manual. How do you explain that?>>>> > -- /"\ Jan Kalin (male, preferred languages: Slovene, English) \ / http://charm.zag.si/eng/, email: "name dot surname AT zag dot si" X ASCII ribbon campaign against HTML in mail and postings. / \ I'm a .signature virus. Copy me to help me spread. |
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#32
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Old Wolf wrote: > Harry K wrote: > > > > > > Speaking of showing ignorance... The old 'slush box' thing went out > > back by the 80s at least. Modern autos have total lockup with only a > > bit of slip during shifts. There is no realistic mpg advantage to > > either one when driven for economy. > > When I converted my car from auto to manual, the mileage > improved by 15% immediately. Also, for motorway driving, > overdrive in the auto was a longer ratio than 5th in > the manual. How do you explain that? 1. Malfunctioning auto. 2. Change in the way you drive. 3. Errors in computing mileage. One sample is not proof of anything. You would have to maintain careful records over many fillups before the results would be meaningful. Not saying any of the apply but you asked for possible explanations. I'm not saying that -every- driver or -every- auto gets the same mileage. What I am saying is the "slush box" arguments are juvenile BS and have been since lockup and overdrive became standard. There will be -some- mpg difference between the two but it will be too small to be an economic consideration for the same driver in the same vehicle in the same conditions. Harry K |
#33
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> wrote in message oups.com... > Finally someone agrees with me. > Yep. And when I do have to drive an auto, I find that its often in the wrong gear for the powerband of the particular engine. With an auto, you have to gun it to downshift or manually do it. Neither is smooth, and most auto trans (newest types excepted) have fewer gears and therefore larger spreads between gears. They just aren't as flexible as MT in the myriad of driving situations we encounter in suburban/urban traffic. For driving in heavy traffic, I find the MT much easier and more economical. I can ride along in second gear for instance at a steady 10mph, whereas with an AT I'd be constantly breaking because it would try to upshift to its highest gear at the lowest speed. Also, I coast alot when I see that I'll need to stop ahead rather than staying on the gas and getting on the brakes hard at the last minute like so many drivers tend to do. What's the point? If you know you're going to stop, why accelerate toward the stop? I wonder if always pushing against the brakes makes for worse fuel ecomony (ie idling at a light in drive) vs a manual where you can sit in neutral or with a foot on the clutch. I do the former to save wear on the throwout bearing. As fuel continues to increase in price more people will be attracted to MT for their ruggedness, simplicity, and better fuel economy potential IMO. My 2¢ |
#34
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"Larry Bud" > wrote:
>> The grade sensor doesn't cost much, I'm sure. > >We in the auto industry try to save *PENNIES* on each piece, because >when you multiply that by 15 million units, it adds up to real money. > >When I was back at Chrysler a few years ago, they had a program that >rewarded employees for coming up with cost reduction ideas. You're right: pennies per vehicle add up fast in high-volume models. But a grade sensor is not really necessary to give a modern car enough information to detect grades. The engine controller can calculate the torque delivered to the drive wheels, based on airflow, ignition timing, etc. With a very simple model of the vehicle's aero drag and rolling resistance, and measurements like vehicle speed, an engine controller (or trans controller) can calculate a force balance on the vehicle. This force balance can be used to estimate the current road grade. The controller doesn't need great accuracy in grade measurements to do useful things like downshifting on long grades, so moderate errors in the drag model are easily tolerated. That said: software isn't quite free (memory and software development cost some money), but it's a lot cheaper and more reliable than a sensor in applications like this. Geek note: the two most variable unknowns in the force balance equation are total vehicle mass (e.g., driver only vs full load) and road grade. To a very basic grade estimation algorithm, a heavy load might look like an uphill or downhill grade, depending on whether the vehicle is accelerating or decelerating, but with a little more work in the algorithm, a useful mass estimate can be created (with the assumption that vehicle load doesn't change rapidly while the vehicle is moving). -- Chuck Tomlinson |
#35
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Chuck Tomlinson wrote: > "Larry Bud" > wrote: > >> The grade sensor doesn't cost much, I'm sure. > > > >We in the auto industry try to save *PENNIES* on each piece, because > >when you multiply that by 15 million units, it adds up to real money. > > > >When I was back at Chrysler a few years ago, they had a program that > >rewarded employees for coming up with cost reduction ideas. > > You're right: pennies per vehicle add up fast in high-volume > models. But a grade sensor is not really necessary to give > a modern car enough information to detect grades. > > The engine controller can calculate the torque delivered to > the drive wheels, based on airflow, ignition timing, etc. > With a very simple model of the vehicle's aero drag and > rolling resistance, and measurements like vehicle speed, an > engine controller (or trans controller) can calculate a > force balance on the vehicle. This force balance can be > used to estimate the current road grade. > > The controller doesn't need great accuracy in grade > measurements to do useful things like downshifting on long > grades, so moderate errors in the drag model are easily > tolerated. > > That said: software isn't quite free (memory and software > development cost some money), but it's a lot cheaper and > more reliable than a sensor in applications like this. > > Geek note: the two most variable unknowns in the force > balance equation are total vehicle mass (e.g., driver only > vs full load) and road grade. To a very basic grade > estimation algorithm, a heavy load might look like an uphill > or downhill grade, depending on whether the vehicle is > accelerating or decelerating, but with a little more work in > the algorithm, a useful mass estimate can be created (with > the assumption that vehicle load doesn't change rapidly > while the vehicle is moving). > -- > Chuck Tomlinson FWIW this seems to have been implemented in some cars; I had the opportunity to drive my friend's Chrysler Concorde on a long road trip that involved driving I-68 from Morgantown to I-70. When on cruise control, the transmission would downshift on a downgrade steep enough to allow the car's speed to creep up. Kind of nice; but it made me think about the notorious unreliability of Chrysler 4-speed automatics... nate |
#36
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N8N wrote: > Chuck Tomlinson wrote: > > "Larry Bud" > wrote: > > >> The grade sensor doesn't cost much, I'm sure. > > > > > >We in the auto industry try to save *PENNIES* on each piece, because > > >when you multiply that by 15 million units, it adds up to real money. > > > > > >When I was back at Chrysler a few years ago, they had a program that > > >rewarded employees for coming up with cost reduction ideas. > > > > You're right: pennies per vehicle add up fast in high-volume > > models. But a grade sensor is not really necessary to give > > a modern car enough information to detect grades. > > > > The engine controller can calculate the torque delivered to > > the drive wheels, based on airflow, ignition timing, etc. > > With a very simple model of the vehicle's aero drag and > > rolling resistance, and measurements like vehicle speed, an > > engine controller (or trans controller) can calculate a > > force balance on the vehicle. This force balance can be > > used to estimate the current road grade. > > > > The controller doesn't need great accuracy in grade > > measurements to do useful things like downshifting on long > > grades, so moderate errors in the drag model are easily > > tolerated. > > > > That said: software isn't quite free (memory and software > > development cost some money), but it's a lot cheaper and > > more reliable than a sensor in applications like this. > > > > Geek note: the two most variable unknowns in the force > > balance equation are total vehicle mass (e.g., driver only > > vs full load) and road grade. To a very basic grade > > estimation algorithm, a heavy load might look like an uphill > > or downhill grade, depending on whether the vehicle is > > accelerating or decelerating, but with a little more work in > > the algorithm, a useful mass estimate can be created (with > > the assumption that vehicle load doesn't change rapidly > > while the vehicle is moving). > > -- > > Chuck Tomlinson > > FWIW this seems to have been implemented in some cars; I had the > opportunity to drive my friend's Chrysler Concorde on a long road trip > that involved driving I-68 from Morgantown to I-70. When on cruise > control, the transmission would downshift on a downgrade steep enough > to allow the car's speed to creep up. Kind of nice; but it made me > think about the notorious unreliability of Chrysler 4-speed > automatics... > > nate Aha, the light dawns. Just bought a new car but the quadrant only has D and L (for forward speeds). I wondered how I was going to lock out the OD driving in Canada this summer. Some of those grades are long and steep. One is 13 miles with no let up at 6 to 7 1/2 percent grade. Dealer couldn't asnwer my question. Book doesn't either. Harry K |
#37
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#38
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Bernd Felsche > wrote:
(Chuck Tomlinson) writes: > >>The engine controller can calculate the torque delivered to >>the drive wheels, based on airflow, ignition timing, etc. >>With a very simple model of the vehicle's aero drag and >>rolling resistance, and measurements like vehicle speed, an >>engine controller (or trans controller) can calculate a >>force balance on the vehicle. This force balance can be >>used to estimate the current road grade. > >Almost. A surface with high rolling resistance is indistinguishable >from a slight gradient or even a fully-laden vehicle using those >means of determination. > >Similarly, dragging brakes. True. But I think it's reasonable to assume some nominal value for rolling resistance and brake drag. If the vehicle is, for example, on a long gravel hill or if the brakes are malfunctioning, I wouldn't (as an owner) expect a downshifting algorithm to function flawlessly. Also, if the surface has high rolling resistance or dragging brakes, the vehicle might not _need_ to downshift (though dragging brakes could quickly lead to the sort of thermal problem a downshift algorithm helps to avoid). [...] >>Geek note: the two most variable unknowns in the force >>balance equation are total vehicle mass (e.g., driver only >>vs full load) and road grade. To a very basic grade >>estimation algorithm, a heavy load might look like an uphill >>or downhill grade, depending on whether the vehicle is >>accelerating or decelerating, but with a little more work in >>the algorithm, a useful mass estimate can be created (with >>the assumption that vehicle load doesn't change rapidly >>while the vehicle is moving). > >I still can't figure out how you're going to determine that the >vehicle is on a level road. The null-point recalibration could be >confused by a slight down-hill run after the vehicle starts moving. I haven't tried to write one of these routines myself, but if I had to start tomorrow :-), after each start I'd reset the assumed payload to driver only, then observe. If the vehicle was heavily laden and the car started downhill, the estimated (downward) grade would be too high and the trans would downshift early. The driver would apply more throttle than my algorithm would expect, and the algorithm would use that information to adjust the mass estimate upwards (slowly) until the driver's throttle application was consistent with the grade estimate. I'm sure it's trickier than I expect, but I'm still pretty sure it can be done with enough fidelity to be more help than hindrance. -- Chuck Tomlinson |
#39
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#40
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On 14 May 2005 17:59:39 -0700, "Harry K" >
wrote: > wrote: >> It's just like acting and being an actor or actress. There are those >> of you who would know what can happen if a person tries to *act a >> certain character* rather than *be a certain character*. There is a >> significant difference. The person just acting is not very credible >> and he/she looks out of sync and overall out of place. >> >> On the other hand actors/actresses who do know how to act (and act >> well), they actually *become* the character rather than *act* the >> character. >> >> Vivian Leah was so good at being her character in front of the camera >> to the point where her career gave her major manic depression that >> could not be controlled by medication. She ended up recieved EST >> (electric shock therapy). That just goes to show how commited she >was >> and that she was an amazing actress. >> >> >> Now keeping all the above in line imagine all the cars in hill >country. >> Everyone driving their cars with manual transmissions are not riding >> their brakes the way those driving their automatic transmission cars >> are doing. This is because the drivers with manual transmissions are >> synchronized with not only the gradients of the road but with their >> vehicles RPM's and MPH as well. >> >> The drivers with their manual transmissions are "being the car", >rather >> than the drivers with their slush boxes that are merely >"acting/driving >> the car". >> >> Ever heard of the expression, "Don't drive the car, be the car"? >Well >> this is where it comes from. >> >> Drivers in their slush box cars should be banned from the road. >Anyone >> so lazy that they can't shift gears and be in sync with the >automobile >> and the road shouldn't be driving. And for the DMV road test, all >> drivers need to required to take the test driving a manual >transmission >> car, otherwise they won't be able to test on an automatic. >> >> It's the principle of it. Drivers in their slush box cars are a >> nuisance on the road, more particularly in hill country. > >While I am a fan of manual myself, your theory lacks credibility. >There is absolutely no difference on the highway between the two as far >as 'being the car' or 'driving the car' goes. Once your speed is up to >the flow, nothing shifts in either tranny for hundreds of miles. It is >only in slow, congested traffic that there is a difference. There I >give the bennies to the slushbox, especially in hilly territory. >Considering 85-90% of drivers on the road who can only 'go with the >car' and barely do that, do you -really- want them screwing with a >manual also?? > >I have one of each. > >Harry K Not to mention, in hilly country, a manual can even be a bit dangerous. Consider, you're heading uphill when you hit a stopsign (Don't laugh, they have areas like this in Three Rivers, California, as well as above Porterville, ) In order to keep from rolling backwards, you'd have to hold your brakes...then, you gotta let off the clutch and give it enough gas, timing it just right so you don't roll back too far and nail the guy behind you, (after, of course, releasing the brakes.) An auto has the advantage here, obviously. -LMB |
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