JHZR2
Staff member
Yep, works fine for my 145 hp BMW.
Its all in the gearing. DC traffic in my E30 318i is an enjoyable situation!
JMH
Automatic VS. Standard Transmission?
- Thread starter dickdog1
- Start date
- Status
Yep, works fine for my 145 hp BMW.
Its all in the gearing. DC traffic in my E30 318i is an enjoyable situation!
JMH
CVTs are less efficient at highway speeds for the same reasons automatics are less efficient at slower speeds: they slip. Only a clutch is direct drive for complete control. CVTs are fine for city driving, but on the open road - they aren't the best.
No racing cars use CVTs - for a reason and they have been tried.
No racing cars use CVTs - for a reason and they have been tried.
My wife has a 2005 Explorer with the 4.6 and 5 speed auto tranny. I have a 2002 F-150 Supercab with a heavy fiberglass high rise cap(350#'s)with the same 4.6 BUT the 5 speed manual tranny. Both have the 3.55:1 rear diff. Mine feels much stronger in general driving. The engine and tranny gearing work real well. Her's seems to strain the engine more to keep up the same speed. She can take off faster and shift faster because the manual tranny in the F-150, while geared nicely shifts poorly. It's very nothcy and clunky. Once in gear the engine and tranny work great and extract the most usable power from the engine. Of course I've driven manual trannies since 1971. So maybe I'm biased
.
Whimsey
Whimsey
ABS helps you stop faster on wet pavement and lets you maintain steering input. On snow and gravel, ABS will increase your stopping distances and can be ineffective. ABS increases stopping distances on dry pavement as well so threshold braking should be used.
A well built manual tranny with a skilled driver is tops. It's downhill from there.
Next best is DSG...
The planetary transmission in the Prius is the most efficient. There is only one speed, no clutches or bands, no friction parts at all and no shifting gears.
Works for my measly 115 hp Corolla. The key is to keep a bit of distance between you and the car in front of you. If you really put put along, you never even have to use the clutch. But having space between you and the car in front angers many drivers behind you. Idiots
No it is not. The power to the wheels in all driving ranges, particularly at higher speeds, is less efficient than a simple sitck shift. It is not direct drive, it works on slippage, in this case making the planetary gear spin more than it would directly geared. it is like having two differentials in line.
There is no electronic or mechanical substitute for:
1-Direct drive
2-Driver judgement
3-Gear ratios
ff:
Please see the great article at the link posted by XS, above. Slippage is not part of the HSD solution. At any rate, consider the end result. The Prius is a car that weighs almost 3,000 lbs. During steady state cruising at highway speed, it still gets substantially better mileage than similar size/weight cars with either stepped automatics or manuals. Just a few minutes ago, I finished a run from Pensacola to New Orleans, just over 200 miles, almost all of it done at just under 80 mph, and my Prius averaged just under 46 mpg. During this type driving, there is only a small in/out flow to/from the battery. I have a CAN View unit grafted into my car, so I can monitor a lot more data than the driver of a "stock" Prius. This is an example of one of the many screens CV offers:
The one I use the most has ICE rpm, ICE temp, instant mpg, in/out charge flow to the battery (CV gives you three such screens, and you can select the displayed parameters for each). During steady-state cruising, there is only miniscule charge flow to or from the battery (as compared to what you see at low speeds, or when you floor it).
What you're missing is that it does NOT work on "slippage". If the ideal setting at one particular moment calls for more ICE rpms, that causes MG1 to spin more as well, putting more juice back into the battery for later use. There is no slippage at all in this unit. Power applied goes either to driving the wheels, or generating electricity, which if not used right away, goes to the battery for later use. What many people miss when looking at this design is what would be slippage in a common belt or chain and cone CVT gets "captured" by the motor-generators in this design, in the form of electricity, and re-used later.
Even with the neat, small, Atkinson cycle ICE, and the very carefully done aerodynamics, this almost-mid-sized, 3k lbs car simply could not achieve the highway fuel economy it does with a "slippy" inefficient transmission.
Please see the great article at the link posted by XS, above. Slippage is not part of the HSD solution. At any rate, consider the end result. The Prius is a car that weighs almost 3,000 lbs. During steady state cruising at highway speed, it still gets substantially better mileage than similar size/weight cars with either stepped automatics or manuals. Just a few minutes ago, I finished a run from Pensacola to New Orleans, just over 200 miles, almost all of it done at just under 80 mph, and my Prius averaged just under 46 mpg. During this type driving, there is only a small in/out flow to/from the battery. I have a CAN View unit grafted into my car, so I can monitor a lot more data than the driver of a "stock" Prius. This is an example of one of the many screens CV offers:
The one I use the most has ICE rpm, ICE temp, instant mpg, in/out charge flow to the battery (CV gives you three such screens, and you can select the displayed parameters for each). During steady-state cruising, there is only miniscule charge flow to or from the battery (as compared to what you see at low speeds, or when you floor it).
What you're missing is that it does NOT work on "slippage". If the ideal setting at one particular moment calls for more ICE rpms, that causes MG1 to spin more as well, putting more juice back into the battery for later use. There is no slippage at all in this unit. Power applied goes either to driving the wheels, or generating electricity, which if not used right away, goes to the battery for later use. What many people miss when looking at this design is what would be slippage in a common belt or chain and cone CVT gets "captured" by the motor-generators in this design, in the form of electricity, and re-used later.
Even with the neat, small, Atkinson cycle ICE, and the very carefully done aerodynamics, this almost-mid-sized, 3k lbs car simply could not achieve the highway fuel economy it does with a "slippy" inefficient transmission.
I understand how a Prius gearbox works. I studied this area for 2 years for work. It is not a free lunch. It does work well for city driving.
However, for highway driving, a Prius with a manual clutch is more efficent than a CVT. A HSD CVT does slip, but not literally. The CVT gears turn at different rates to waste mechanical power to make the CVT run without binding. I.e. the planetary gears have to spin at relatively mismtached rates to work, plus this is a hybrid. You have an extra power source. Any "slippage" from the CVT has to be counted as "net" energy after the battery transfer loss.
This works great in city driving where the regenerative braking captures wasted energy you would never get in a regular car and the CVT rotates (slips) less relative to the momentum needed. Automatics are very wasteful in the type of driving cycle (and boring to drive!) and manuals, while direct drive, are more efficient, but must be driven, like a hybrid, dilegently to advantage of the effiency and response in city driving.
On a highway cycle, a manual is clearly and proven to be more efficent than a CVT, Toyota HSD or belt driven. There have been test mules (manual vs. CVT) from Honda, Toyota, GM, Ford that have proven this. There is a manual Prius test mule that has been tested to give the base line data.
The Prius is an amazing car, but it is version 1.1 in the whole world of alternative car technology.
CVTs have been studied extensively in Formula 1 racing (highest form of technology in automotive world) and have found to have many positives, but also some large negatives. So they are using electronic clutches for F1, including Toyota.
Toyota also still sells 99% manuals (mostly diesels) in Europe, since the hybrid offers limited efficiency and performance advatnage (for the cost)for non-city driving.
The CVT is sold in markets that are primarily automatics (USA and Japan) to offer a more efficent alternative to automatics. Issue is, that automatics with a lock-up overdrive are often as, if not more efficient, than CVTs at highway speeds, but are often much worse at city and mixed driving. Depends on what you want to use it for.
However, for highway driving, a Prius with a manual clutch is more efficent than a CVT. A HSD CVT does slip, but not literally. The CVT gears turn at different rates to waste mechanical power to make the CVT run without binding. I.e. the planetary gears have to spin at relatively mismtached rates to work, plus this is a hybrid. You have an extra power source. Any "slippage" from the CVT has to be counted as "net" energy after the battery transfer loss.
This works great in city driving where the regenerative braking captures wasted energy you would never get in a regular car and the CVT rotates (slips) less relative to the momentum needed. Automatics are very wasteful in the type of driving cycle (and boring to drive!) and manuals, while direct drive, are more efficient, but must be driven, like a hybrid, dilegently to advantage of the effiency and response in city driving.
On a highway cycle, a manual is clearly and proven to be more efficent than a CVT, Toyota HSD or belt driven. There have been test mules (manual vs. CVT) from Honda, Toyota, GM, Ford that have proven this. There is a manual Prius test mule that has been tested to give the base line data.
The Prius is an amazing car, but it is version 1.1 in the whole world of alternative car technology.
CVTs have been studied extensively in Formula 1 racing (highest form of technology in automotive world) and have found to have many positives, but also some large negatives. So they are using electronic clutches for F1, including Toyota.
Toyota also still sells 99% manuals (mostly diesels) in Europe, since the hybrid offers limited efficiency and performance advatnage (for the cost)for non-city driving.
The CVT is sold in markets that are primarily automatics (USA and Japan) to offer a more efficent alternative to automatics. Issue is, that automatics with a lock-up overdrive are often as, if not more efficient, than CVTs at highway speeds, but are often much worse at city and mixed driving. Depends on what you want to use it for.
- Status
