I love the CVT in my Nissan

[Meghan54]

I drove some of the early, cheaper, CVT's that seemed to cruise endlessly at like 4,000rpm. Horrible. I think most of the newer ones are using 'simulated' gears (and generally just smarter TCM programming) now, which alleviates that. But then I fail to see the point I thought the CVT was made for: fuel economy, by keeping the engine in the most efficient RPM range.

Which makes me think it's now just a penny-pinching measure, rather than innovative new tech.

First, understand CVT tech is anything but new tech. A CVT was first conceptualized/described in 1490 by Da Vinci. Daimler and Benz patented a car-based belt CVT in 1886. The first U.S. patent granted for a vehicle CVT was in 1935. So the tech is anything but new.

And there are a host of types of CVTs out there....toroidal, magnetic, Reeves (variable diameter pulley system), hydrostatic, ratcheting, cone, and planetary, among others.

As for CVTs in high horsepower vehicles, CVTs have been used in racing since the 1970's, a la the SCCA Formula 500 series, and were banned from F1 in 1994.

And I doubt the Japanese are stupid enough to trust a CVT transmission in their new main battle tank, the Type 10, which is a 48 ton tank with an 8 cyl 1200 hp diesel (the combination can achieve 70kph, or 42mph, in forward and reverse), produced by Mitsubishi Heavy Industries, unless they were quite satisfied with its performance during development and testing....something that had been ongoing since the 1990's and just began fielding this past January.

As for vehicles, Caterpillar, for instance, puts CVTs in many of its earthmovers, etc., and I doubt Caterpillar is another stupid company making stupid decisions by using CVTs.

Now, I cannot speak for every vehicle on the road, as no one here can, either, but having seen a few here in the U.S. and Europe, CVTs can and do work well provided the CVT is designed properly and used appropriately.

Unfortunately, some CVTs have been used inappropriately and were calibrated badly. Such is life.

But with my Murano, the vehicle I've got the most experience with using a CVT, it does indeed keep the rpm's down when cruising the highway, like under 1500rpm at 65mph or better. Even at 80mph, the vehicle--while cruising--does not hit 2000rpm.

Don't fear the past becoming the present. Fuel economy standards increasing and fuel prices climbing will only hasten the CVT becoming the "standard" automatic.....they're all over the place these days if you look closely enough. Audi, Honda, Toyota, Ford, GM, Chrysler/Fiat, Subaru, Nissan, BMW, MB, and almost every other car manufacturer has used, does use, and/or plans on using CVTs in some, if not most, of their vehicles that have autos. For better or worse, they're here and will spread, while the manual trans. will continue to decline in popularity and use.

 

[phucheneh]

...wasn't really trying to shit too hard on CVT's. Just saying anyone who drove the early (in terms of popular use on modern cars) economy cars with them is probably a little jaded, and understandably so. I've heard the CVT Versa was pretty bad, and I've definitely driven one Nissan...Altima, I think? Little older than the Versa (CVT was new for 2011 I thinnk?) I...did not like it. But then again for my personal use, I just prefer the control of a regular manual. With a positive but smooth shifter and an easy clutch...I'm not one of those RRRAAAWWWRRRR LEG-BREAKING NOTCHY MANUAL OR DIE kind of guys.

Are you saying your car does or doesn't do the 'pretend' gear changes? Or is it just a subtle mix of that and gradual changes? I agree that it's all about how the software for the trans computer is done. And I bet makes using lots of CVT's are probably doing/have done lots of software flashes through their dealers.

 

[Doppel]

First, understand CVT tech is anything but new tech. A CVT was first conceptualized/described in 1490 by Da Vinci. Daimler and Benz patented a car-based belt CVT in 1886. The first U.S. patent granted for a vehicle CVT was in 1935. So the tech is anything but new.

And there are a host of types of CVTs out there....toroidal, magnetic, Reeves (variable diameter pulley system), hydrostatic, ratcheting, cone, and planetary, among others.

As for CVTs in high horsepower vehicles, CVTs have been used in racing since the 1970's, a la the SCCA Formula 500 series, and were banned from F1 in 1994.

And I doubt the Japanese are stupid enough to trust a CVT transmission in their new main battle tank, the Type 10, which is a 48 ton tank with an 8 cyl 1200 hp diesel (the combination can achieve 70kph, or 42mph, in forward and reverse), produced by Mitsubishi Heavy Industries, unless they were quite satisfied with its performance during development and testing....something that had been ongoing since the 1990's and just began fielding this past January.

As for vehicles, Caterpillar, for instance, puts CVTs in many of its earthmovers, etc., and I doubt Caterpillar is another stupid company making stupid decisions by using CVTs.

Now, I cannot speak for every vehicle on the road, as no one here can, either, but having seen a few here in the U.S. and Europe, CVTs can and do work well provided the CVT is designed properly and used appropriately.

Unfortunately, some CVTs have been used inappropriately and were calibrated badly. Such is life.

But with my Murano, the vehicle I've got the most experience with using a CVT, it does indeed keep the rpm's down when cruising the highway, like under 1500rpm at 65mph or better. Even at 80mph, the vehicle--while cruising--does not hit 2000rpm.

Don't fear the past becoming the present. Fuel economy standards increasing and fuel prices climbing will only hasten the CVT becoming the "standard" automatic.....they're all over the place these days if you look closely enough. Audi, Honda, Toyota, Ford, GM, Chrysler/Fiat, Subaru, Nissan, BMW, MB, and almost every other car manufacturer has used, does use, and/or plans on using CVTs in some, if not most, of their vehicles that have autos. For better or worse, they're here and will spread, while the manual trans. will continue to decline in popularity and use.

Good info!

...wasn't really trying to shit too hard on CVT's. Just saying anyone who drove the early (in terms of popular use on modern cars) economy cars with them is probably a little jaded, and understandably so.

Fair statement. The Subaru Justy in the early 90's was the first US vehicle to have it, I believe, and it was not a strong transmission at that time.

The current lot of Nissan's, at least the ones with a V6, will have RPM sub-2k when cruising, at all speeds.

There are no pretend gear changes, though it is possible to put the cars into a mode that acts like it has several gears and then you manually change (mostly worthless).

I'd love to try the most recent Altima V6 because I hear its transmission is quicker than the last gen. Regardless of what CVTs are today I firmly believe that one properly made would give an undeniably superior experience, pulling in even the most eager detractors, from a standard geared transmission. I still believe it should be possible to hit the throttle and have an almost instantaneous jump to peak power, resulting in the very best acceleration. At this time unfortunately there is still a sizeable delay between flooring the cars and when the RPM finally hit their peak point.

 

[JCH13]

This is sounding like carbs vs fuel injection all over again. Sure, the first iterations of fuel injected cars were not as good as the latest carbs, but every new vehicle is fuel injected now and no one thinks twice about it. I predict that CVTs will be similar, clearly some of the latest iterations aren't as good as the latest automatics, but soon CVTs will match, and then surpass, automatics in terms of performance and maybe reliability.

 

[Jeff7]

...
That's because unlike your normal planetary-gear-based automatic transmission, CVTs do not use viscous torque converters. Those torque converters are what allow the usual automatic to roll like that as it does not have a direct mechanical linkage to the engine.

Ok.


Some of it does have to do with the gearing ratio the transmission uses though. If I'm going downhill and the engine braking starts to kick in automatically, if I flip it up into 5th or 6th gear, it eases up and I start to coast more freely - though yes, I'm sure once the RPMs start to go up, I'd again start to see the braking effect.
The transmission's programmed behavior appears to be to want to maintain the vehicle's speed, or decrease it slightly, rather than let it pick up a lot of speed on a downward slope.

 

[Yourself]

My wife has a '09 Murano and I still haven't got used to the CVT. I really don't care for it at all. Luckily I drive it about 6 times a year.

 

[nerp]

I have an 8-speed transmission in my car. I've driven a newer CVT and hands down, the 8-speed is better. You really can't detect gear changes unless you floor it with the 8-speed ZF and it shifts faster than any human can, so there is no real "lag" to speak of. 1500rpms at 85mph getting 35 mpg easy doesn't hurt either, especially when your car is 4300 lbs like mine.

 

[Aikouka]

But with my Murano, the vehicle I've got the most experience with using a CVT, it does indeed keep the rpm's down when cruising the highway, like under 1500rpm at 65mph or better. Even at 80mph, the vehicle--while cruising--does not hit 2000rpm.

Hmm I can't go 65-70 without going over 2k RPMs in my Altima (70 = 2.2k RPM). Although, it might matter that it's the V6 trim not the I4.

 

[gorcorps]

Hmm I can't go 65-70 without going over 2k RPMs in my Altima (70 = 2.2k RPM). Although, it might matter that it's the V6 trim not the I4.

That's about what my Rogue gets. It's right above 2k at fast highway speeds, and when accelerating when merging it's ~4k. Under 65 it goes below 2k.

 

[Aikouka]

That's about what my Rogue gets. It's right above 2k at fast highway speeds, and when accelerating when merging it's ~4k. Under 65 it goes below 2k.

Hmm I don't see that high of RPMs unless I'm really pushing down on the accelerator. Modest acceleration only puts me at around 2k to 3k depending on my current speed.

 

[phucheneh]

That sounds like a CVT actually working like I initially envisioned it could/should. Which is good.

Again, I know the tech has existed for a while, but its been maybe five years or so since they're begun to see widespread use in passenger cars. Especially non-hybrids. I just don't know what they were thinking with the programming of some of those early units. Maybe they deemed a certain RPM to have peak efficiency, ignoring throttle position, and just said 'I'll just tell the TCM to keep it there all the time. Done.'

 

[The Boston Dangler]

it's too bad cvt didn't reach maturity ages ago. maybe it will still find a home in the future between the engine and electrical generator.

 

[phucheneh]

The starter-generator goes in the middle. That way the wheels can generate power, and when needed (a lot), the same kajigger (I'm obviously a highly trained hydrid guy-thingy, right?) can start the engine. I dunno if they have it down to using the same coils of wire for both purposes. But...same unit, at least.

I think hydrids will die. It's just captured energy from the car slowing down. And most don't/can't/ and/or don't want to drive it in a way that really lets it generate that much power. It's clever power-recovery, but the expensive parts don't really make it worthwhile.

In the end, it's probably just pretty hard to make a car that doesn't have a gas engine running all the time not suck to drive. For the hybrid vehicles, I say use smaller batteries and let the electrical motor assist the gas engine, not vice versa. With no direct link to the drivetrain- just using advanced compu-mo-tation to help turn the crankshaft of the engine as needed. Would have to be a pretty elegant dance between its doings and the air/fuel system, but some engineer-o-motron can worry about that.

Or better yet, just run all accessories off of the 'regenerative braking' effect. More simpler-mo-doodle. Prius already does some of the that (I know the AC compressor is hooked to the high voltage system).

But in the end, you have to wonder how much net efficiency you're really gaining. I wonder how much energy it takes to turn over the Prius's engine versus a normal 12v starter? All that copper probably sucks up more juice than the motor powering an old school gear reduction system.

 

[LTC8K6]

Since MG1 is already there, and usually already turning, the "starter" in the Prius is "free". It also turns the engine much faster when it starts it, about 1K revs before spark and fuel are turned on.

 

[Doppel]

Hybrids are certainly not dying, and instead are gaining a stronger foot hold all the time.

The "electrical motor assist the gas engine" is how the Honda hybrid system works, and it's inferior to Toyota's (and others') approach, delivering simplicity and lower cost but much worse mileage.

A full electric based system is what allows the Prius to stop its ICE at lights while still running AC, be completely belt-less, and get city mileage twice that of a comparably sized mid-size hatch-back and around 25% better on the highway.

Having spent some time driving an EV I can tell you that not only is an ICE not needed to have a good driving experience, but that it robs it. As EVs very slowly, gradually gain a foothold one of the things they will continue to be touted for is their class-leading throttle response and smoothness of drive train. Some will miss the sound of an engine under throttle but in time (many many decades) it will be seen as an anachronism, similar to that commercial that has the gas powered razor and hair dryer.

 

[JCH13]

The starter-generator goes in the middle. That way the wheels can generate power, and when needed (a lot), the same kajigger (I'm obviously a highly trained hydrid guy-thingy, right?) can start the engine. I dunno if they have it down to using the same coils of wire for both purposes. But...same unit, at least.

I think hydrids will die. It's just captured energy from the car slowing down. And most don't/can't/ and/or don't want to drive it in a way that really lets it generate that much power. It's clever power-recovery, but the expensive parts don't really make it worthwhile.

Got any numbers to back up that wild claim? 😉

In the end, it's probably just pretty hard to make a car that doesn't have a gas engine running all the time not suck to drive. For the hybrid vehicles, I say use smaller batteries and let the electrical motor assist the gas engine, not vice versa. With no direct link to the drivetrain- just using advanced compu-mo-tation to help turn the crankshaft of the engine as needed. Would have to be a pretty elegant dance between its doings and the air/fuel system, but some engineer-o-motron can worry about that.

Basically everything downstream of the electric motor in the powertrain has to be beefed up, so all the engineer-o-motrons put electric motors as close to the wheels as is practical. The crankshaft is just about as far away from the wheels as you can get.

Or better yet, just run all accessories off of the 'regenerative braking' effect. More simpler-mo-doodle. Prius already does some of the that (I know the AC compressor is hooked to the high voltage system).

But in the end, you have to wonder how much net efficiency you're really gaining. I wonder how much energy it takes to turn over the Prius's engine versus a normal 12v starter? All that copper probably sucks up more juice than the motor powering an old school gear reduction system.

You're worried about a few percent efficiency on starting the car, an incredibly tiny fraction of the energy consumed by the vehicle? Really?

Also, gearing reductions have their own efficiency losses, generally ranging from 2%-20% loss if aligned and lubed perfectly, but losses are often much more than 2%.

 

[LTC8K6]

Hybrids are certainly not dying, and instead are gaining a stronger foot hold all the time.

The "electrical motor assist the gas engine" is how the Honda hybrid system works, and it's inferior to Toyota's (and others') approach, delivering simplicity and lower cost but much worse mileage.

A full electric based system is what allows the Prius to stop its ICE at lights while still running AC, be completely belt-less, and get city mileage twice that of a comparably sized mid-size hatch-back and around 25% better on the highway.

Having spent some time driving an EV I can tell you that not only is an ICE not needed to have a good driving experience, but that it robs it. As EVs very slowly, gradually gain a foothold one of the things they will continue to be touted for is their class-leading throttle response and smoothness of drive train. Some will miss the sound of an engine under throttle but in time (many many decades) it will be seen as an anachronism, similar to that commercial that has the gas powered razor and hair dryer.

I wonder if our electrical grid or our power generating system will support large scale EV use any time in the next few decades? There's really very little sign of upgrading the grid or of increasing capacity.

Then there's the fact that no one will want a new power plant of any sort built near them.

Tesla's stations are a start, but they aren't the solution, and they aren't all they are cracked up to be.

http://www.thetruthaboutcars.com/2012/09/the-truth-about-teslas-charging-stations/

The amount of electrical power consumed by EV's is stunning.

 

[Zenmervolt]

Hybrids are certainly not dying, and instead are gaining a stronger foot hold all the time.

The "electrical motor assist the gas engine" is how the Honda hybrid system works, and it's inferior to Toyota's (and others') approach, delivering simplicity and lower cost but much worse mileage.

A full electric based system is what allows the Prius to stop its ICE at lights while still running AC, be completely belt-less, and get city mileage twice that of a comparably sized mid-size hatch-back and around 25% better on the highway.

Having spent some time driving an EV I can tell you that not only is an ICE not needed to have a good driving experience, but that it robs it. As EVs very slowly, gradually gain a foothold one of the things they will continue to be touted for is their class-leading throttle response and smoothness of drive train. Some will miss the sound of an engine under throttle but in time (many many decades) it will be seen as an anachronism, similar to that commercial that has the gas powered razor and hair dryer.

Unless and until you can "refuel" an EV for a 300 mile range in under 10 minutes, they will not catch on as primary vehicles. I can see people with 2-car households having one EV and one "traditional" car (or one EV and one hybrid), but I don't see EVs being in a position to take over yet.

Hybrids are a stopgap technology and I don't see a future for them once the ICE-only cars die (and at some point they will).

I still believe that the hydrogen fuel cell is the best currently-available technology for replacement of the ICE. The HFC concept allows solid range, easy refueling, zero emissions, and the practical benefits of electric-motor propulsion. I think this may be what you were talking about when you were talking about EVs, but I and many others tend to immediately think "battery" when someone just mentions EV, so I apologize if that was what happened here.

ZV

 

[Jeff7]

I wonder if our electrical grid or our power generating system will support large scale EV use any time in the next few decades? There's really very little sign of upgrading the grid or of increasing capacity.

Then there's the fact that no one will want a new power plant of any sort built near them.

Tesla's stations are a start, but they aren't the solution, and they aren't all they are cracked up to be.

http://www.thetruthaboutcars.com/2012/09/the-truth-about-teslas-charging-stations/

The amount of electrical power consumed by EV's is stunning.

Sort of - I like thinking of a car engine in terms of watts. 🙂
1HP = 745.7W

So a 150HP engine is almost 112 kilowatts.
305HP in the Subaru WRX STI = 227.5 kilowatts.

 

[LTC8K6]

Sort of - I like thinking of a car engine in terms of watts. 🙂
1HP = 745.7W

So a 150HP engine is almost 112 kilowatts.
305HP in the Subaru WRX STI = 227.5 kilowatts.

Right, but it's not from the grid.

 

[Jeff7]

Right, but it's not from the grid.

Ah, ok - didn't know that that was the specific context you were going for. 🙂


Yeah....and for a power "grid" like the one in the US, well, the added drain from electric cars would open up a few new puns for "rolling" blackout. :sneaky:

 

[Kroze]

How is the reliability?

I have 120,000 miles on my Maxima which is 9 years old and have never had any trouble with the automatic transmission... knock on wood.

Then again, 95-03 Maximas are known to be one of the most reliable vehicle (engine & transmission wise). Although my opinion may be bias

🙂

 

[foghorn67]

I'm glad Nissan has come a long way with CVT's. I drove a Mitsu SUV with a CVT and it was terible. Even enthuisist mags say Nissan is getting damn good.

But....I am more intrugued by the new 8 speeds in Audi's,BMWs and Chryslers.
The A4 has only 200 horses and rips a sub 6 second 0-60 and has decent overall fuel economy. (Not EPA, real world test loops by car mag editors with lead foots).

 

[nerp]

Foghorn67 —*the ZF 8-speed is sick. As in awesome. Go on a test drive.

 

[hans007]

I'm glad Nissan has come a long way with CVT's. I drove a Mitsu SUV with a CVT and it was terible. Even enthuisist mags say Nissan is getting damn good.

But....I am more intrugued by the new 8 speeds in Audi's,BMWs and Chryslers.
The A4 has only 200 horses and rips a sub 6 second 0-60 and has decent overall fuel economy. (Not EPA, real world test loops by car mag editors with lead foots).

The a4 also has 258 lb ft of torque. So its misleading. The 2.0t could probably make 300hp like in the new s3 if Audi wanted.

Zf does make a good transmission that 8 speed is in everything now