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cvt

norseamd

norseamd

Lifer
so what are the current utilization of cvt in passenger vehicles?

where is cvt technology as far as high power applications? sports cars? the type 10 uses a cvt so there are some cvts that can be used in high power applications

what are the differences between the different cvt types
 
no but wikipedia mostly lists the technical differences between cvt types and that is hard to understand for me
 
alright so going back to wikipedia the article is definitly better written than it was a while ago. that said it is still hard for me to understand about the different types when there is no comparision table. so do any of you know about high performance use of cvts?

a better phrase of the question would be what do people with experience with cvts think of the current cars with them and the reliabilty and gas mileage and ease of use and such?

this thread was originally going to be a post about what are the current offerings of cvts in the large cars segment in the larger car thread but i decided to make a thread about it and i just went to making it right away. that said a car expert could certainly give me more understanding of cvts.

thankyou
 
The new 2015 WRX is the only "performance" car that I've read that will utilize a CVT. I personally like the transmission for everyday commuters. It's smooth and gets good gas mileage. But I'll be interested to see how it feels in a WRX.
 
I really like them. For Subaru, they have provided big increases in fuel economy. I have had a 2010 Outback and 2014 Forester, both with a CVT. I would now consider a traditional automatic a big negative when evaluating future vehicles.
 
seems that the cvt in the wrx is slower than the manual transmission. although you do get better gas mileage. the cvt in the wrx apparantly has a intelligent a sport and a sport # for cvt modes. not sure if it is just the sport # but apparantly you use paddle shifters to move the cvt to 8 different pre selected gear ratios. i thought the whole point of cvts was a continuously variable transmission
 
norseamd said:
seems that the cvt in the wrx is slower than the manual transmission. although you do get better gas mileage. the cvt in the wrx apparantly has a intelligent a sport and a sport # for cvt modes. not sure if it is just the sport # but apparantly you use paddle shifters to move the cvt to 8 different pre selected gear ratios. i thought the whole point of cvts was a continuously variable transmission
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You do not need to use the paddles. Actually not using them, and letting the CVT manage itself will be quicker. I only ever used the paddles for compression braking.
 
CVT is more efficient (unlimited gear ratios) but it's not as robust as a conventional geared automatic transmission. Which is why you don't, and probably never well see it in heavy duty applications like trucks and performance cars.

The only car I've driven with CVT is the Suzuki SX4. You get very smooth power output with it, almost like an electric car. The engine does tend to drone though.
 
Nissan and Subaru are all pretty much on CVTs.. looks like rest are starting to follow.

you'll see them on every care after 2016 when new govt mandates become mandatory,
 
Jumpem said:
You do not need to use the paddles. Actually not using them, and letting the CVT manage itself will be quicker. I only ever used the paddles for compression braking.
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so how fast can it go compared to a manual or paddle shifted transmission

mmntech said:
CVT is more efficient (unlimited gear ratios) but it's not as robust as a conventional geared automatic transmission. Which is why you don't, and probably never well see it in heavy duty applications like trucks and performance cars. The only car I've driven with CVT is the Suzuki SX4. You get very smooth power output with it, almost like an electric car. The engine does tend to drone though.
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yeah i know. that is why i asked. the cvt in the type 10 can apparantly handle 1200 horsepower although.

http://en.wikipedia.org/wiki/Type_10
 
Can't speak for other CVTs, but the CVT in my Crosstrek seems to be geared/programmed towards fuel efficiency, at times when I need the power climbing it would dick around until I either give it more gas or shift into manual mode and knock it down a gear myself. It's a balance between power and efficiency, but sometimes it rides on the wrong side of the fence.

The Nissan Sentra we've test driven was like, how do you say it, a Honda Civic with a huge ass exhaust that rumbles away when the light turns green but doesn't go anywhere at all. Sentra's CVT whines loudly when you get aggressive with the gas pedal but nothing really happens, and that's scary when you're in a situation you need to get out of and can't rely on it to perform.
 
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I've driven automatics most of my life and am now using a CVT Prius as the daily commuter. I have also driven a Nissan Versa CVT as a rental. When comparing the CVT vs automatic, I would pick the CVT every time. The Toyota's CVT w/ hybrid combination is quite nice. It's efficient, has enough power when you need it, and I personally like the lack of "jerking" that comes from manual and automatic trannies. You do have to get used to the "rubberband" feel of the accelerator pedal but that's small stuff. Toyota CVT vs Nissan CVT, the Toyota beat it out. It just felt smoother. I haven't driven the Subie CVTs but I know that the old 4-speed auto transmission on my 2008 Impreza pushed me to switch cars. It was way too jerky and indecisive.

I think most cars, minus Mazda are wandering into CVT transmissions vs having an automatic as an option. I think it's the right move.
 
The CVTs used in newer hybrid cars, such as the Toyota Prius, Highlander and Camry, the Nissan Altima, and newer-model Ford Escape Hybrid SUVs should be of a solid design due to the use of electric motors and simple gears (much like a differential) vs. CVT design of most other makes and models of vehicles.
 
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PeeluckyDuckee said:
Can't speak for other CVTs, but the CVT in my Crosstrek seems to be geared/programmed towards fuel efficiency, at times when I need the power climbing it would dick around until I either give it more gas or shift into manual mode and knock it down a gear myself. It's a balance between power and efficiency, but sometimes it rides on the wrong side of the fence.

The Nissan Sentra we've test driven was like, how do you say it, a Honda Civic with a huge ass exhaust that rumbles away when the light turns green but doesn't go anywhere at all. Sentra's CVT whines loudly when you get aggressive with the gas pedal but nothing really happens, and that's scary when you're in a situation you need to get out of and can't rely on it to perform.
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Sounds like you don't understand in the least how an ICE + CVT work.
 
norseamd said:
a better phrase of the question would be what do people with experience with cvts think of the current cars with them and the reliabilty and gas mileage and ease of use and such?
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I have a '11 Nissan Altima sedan with the 3.5 V-6 and a CVT. Its been mostly like driving a car with a regular automatic transmission.
 
Simply put, ICEs have a power curve. Traditional automatics have fixed ratios so you're not spinning the engine at either it's most efficient or most powerful speed. By having a CVT, the ratio is infinitely variable so you can operate the engine at a specific speed regardless of the speed the car is moving.
 
NutBucket said:
Simply put, ICEs have a power curve. Traditional automatics have fixed ratios so you're not spinning the engine at either it's most efficient or most powerful speed. By having a CVT, the ratio is infinitely variable so you can operate the engine at a specific speed regardless of the speed the car is moving.
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Just pick an RPM you like and stay there until up to speed. 🙂
 
NutBucket said:
Simply put, ICEs have a power curve. Traditional automatics have fixed ratios so you're not spinning the engine at either it's most efficient or most powerful speed. By having a CVT, the ratio is infinitely variable so you can operate the engine at a specific speed regardless of the speed the car is moving.
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Well they're not INFINITELY variable, at least the CVTs used in cars today aren't. They have infinite gears between specific ratios which means that after a certain point, in order to accelerate, the engine speed has to increase and also at the slowest speed the car doesn't have infinite torque to move forward otherwise the creep function wouldn't work too well as the car would constantly be moving no matter how hard you press on the brakes! But at least you'd have one hell of a stump puller! 😀
 
Jumpem said:
Just pick an RPM you like and stay there until up to speed. 🙂
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So say if I'm climbing up a hill in D (automatic) and it feels sluggish, and I drop it into "manual" mode where it indicate it's at "gear" 4, and I drop it down a gear to "gear" 3 @ 4700rpm (lets say this is the optimal peak torque for the engine), what exactly is happening? Is the engine really running at 4700rpm? Am I controlling the CVT or the engine? I know these questions probably sound very silly, but I'm trying to wrap my head around what's going on mechanically under the hood.

If I leave it in D uphill, am I already in the most ideal position? Uphill I want the most power I can get, not gas savings.
 
It's also a function of throttle position. If the ecu sees the car slowing down and you giving it more throttle it knows you're climbing a hill and responds appropriately to give you the oomph you need.
 
PeeluckyDuckee said:
So say if I'm climbing up a hill in D (automatic) and it feels sluggish, and I drop it into "manual" mode where it indicate it's at "gear" 4, and I drop it down a gear to "gear" 3 @ 4700rpm (lets say this is the optimal peak torque for the engine), what exactly is happening? Is the engine really running at 4700rpm? Am I controlling the CVT or the engine? I know these questions probably sound very silly, but I'm trying to wrap my head around what's going on mechanically under the hood.

If I leave it in D uphill, am I already in the most ideal position? Uphill I want the most power I can get, not gas savings.
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If you want the most power up a hill then you floor the accelerator, in D. The only purpose of "manual mode" is actually for engine BRAKING, especially in a CVT transmission OR if you want to increase throttle response by keeping the revs up. But you said you were simply climbing a hill and want maximum power which in that case, it IS always available, you just have to press the accelerator to the point where you're satisfied.

Gear selections in a CVT are completely irrelevant when you're flooring the accelerator because maximum power is always available at that point. When you see options such as "ECO, Snow, Normal, Power" those are all really just settings that adjust throttle response and how eagerly the transmission will kick down into low gear. Low gear=high RPM. On the Honda Civic HX from '96-'05 there is an "S" option which means "sport" right above the lowest option, "L" which means Low gear. The "L" option is intended to assist in engine braking when going down a hill while the "S" option just makes the car more rev happy at partial throttle positions. However I have to drive home the point that the car will accelerate the same in all the gear selections, especially in a CVT. I have read some anecdotal evidence that on an automatic, most will shift before redline so what some drivers do when racing is put it in manual mode so that they can upshift @ the redline, slightly improving their acceleration times.

However I wouldn't drive like that which in that case means for you that there is nothing for you to do except keep up with the maintenance on the car and don't beat it to shit.

NutBucket said:
It's also a function of throttle position. If the ecu sees the car slowing down and you giving it more throttle it knows you're climbing a hill and responds appropriately to give you the oomph you need.
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Actually NEWER cars are more sophisticated than that. It's a few things. The car sees the load on the engine increase, the car may see an increase in throttle angle (you pushing on the gas more), the MPH drops below the car's specified speed for the particular gear you're in-causing a downshift and finally some cars have gyroscopes where they'll detect you climbing a hill and will not only shift early but will also keep that gear until you've crested the hill, even if you let up on the accelerator while ascending the hill. As a hypermiler, I hate that last feature because I'm more aware of what is going on than the car is and I don't want it prematurely downshifting but I can understand why cars have it as most drivers likely benefit from it.
 
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