Ok wait let me get this straight this new engine from Nissan DOESN'T shift?

 

As far as I know, most engines do not shift. Some transmissions do not shift though....a la CVT.

 

http://en.wikipedia.org/wiki/Continu...e_transmission

 

My bad i meant transmission lol

 

The Murano has had a CVT since its debut in 2002. Nissan has since expanded it to the 4G Altima, 6G Maxima and now the new Sentra.

 

i had a loner with 6 speed auto cvt
i didnt like it i enjoy the distinct shifts the cvt extends the shifts too much.

 

i am embarrassed that we live in the same state

lol

 

 

I suppose one could argue that it shifts continously...

Nissan is the standard bearer for the CVT, personally they scare me in terms of repair, though I have no numbers it would seem they would be much more expensive to repair than conventional trannies and the lack of expertise outside the dealer network.

On a side note they are supposed to be gas savers but Chabba Cherry's (errr Csaba Csere's) byline in the May 07 C&D disputes this.

 

And don't forget the Versa.

 

CVT Sucks, it's unresponsive and takes away the feeling of driving a car. I feel disconnected from the car when i drive my buddies murano.

 

I agree, CVT = dumb

I guess if you like numbness in your life, go for it.

 

I agree that driving a vehicle equipped with a CVT is not very inspiring.......but then again I don't think that will matter much to the average driver (soccer moms, etc).

 

I rented a 07 Maxima with the CVT, goes like stink but like others have said you do miss the ups and downs of the tach.

 

CVT = Shit

 

CVTs are friction drives, and hence, cannot take a lot of torque from the get go. The two main designs (belt and toroidal) are relatively simple, and I wouldn't imagine would have high repair costs if they did fail.

In addition, CVTs offer the POTENTIAL to be better than any other transmission out there in terms of performance as you can keep an engine in the perfect RPM range throughout acceleration.

Mike

 

.....forgot to mention that one....but then again, the Versa is a forgettable car.

 

Actually the DSG transmission from VW/Audi is the best transmission in performance and acceleration. Uses two clutch discs and can be used in manual or auto mode.

 

DSG uses set gear ratios, meaning that it cannot keep the engine in the PERFECT rpm range at all times during acceleration like a CVT type transmission potentially can.

again, a CVT type transmission has the best potential to keep a car in the optimal RPM during acceleration at all times during acceleration.

 

what is the power loss through the drivetrain in a cvt equiped car vs. an auto tranny?

 

"Our tests reveal that the CVT extracts more performance from the 122-hp, 1.8 liter four banger than does the automatic, which is hardly surprising. The CVT can keep the engine very near its 6000-rpm peak for all but the first few feet of the quarter mile, whereas the automatic lets the engine get as much as 1500 rpm off the power peak after each shift. Those excursions from peak power cost time once the cars are launched. " - Csaba Csere, CD May 07 (Nissan Versa CVT vs. Automatic)

 

No numbers but at least in the Versa the hydralic losses are higher with the CVT due to the hydralic pump.

Comparison table in CD this month:

Veras
cvt Auto
0-30 3.1 3.1
0-60 8.9 9.5
0-100 33.5 35.2
1/4 17.0/81 17.3/79
30-50 4.8 5.2
50-70 6.7 7.4

EPA C 30 28
EPA H 36 35
CD test 33.2 35.4


Still curious about repair costs, someone mentioned they thought they would be resonable but I am dubious, anyone have any reference or real world data?

 

 

Well the main design being used on cars now is the belt design... So you have 2 sets of tapered disks that vary there distance apart from each other and a belt which rises and falls front he center point. The actuation system is not nearly as complicated as the valve body and gear sets of an auto. A rebuild would be much less involved.

Mike

 

http://www.trainingpeaks.com/login.asp?orgid=&msg=

Here run a marathon
I needed structure in my life because I would work out for 2 to 4 months, get in shape then lose focus. I think the best thing to do for people who don't like to work out is to have a goal. Mine is to run a marathon in October and keep running them yearly after that. It keeps you in shape because you have a goal...I dunno.

 

 

Duh, are you THAT dense?

 

This is a good thread.

 

DSG > *

MKV GTI 6MT goes 0-60 in 7.1 seconds
MKV GTI 6DSG does it in 6.8 seconds

Also keep in mind, that 6.8 does not take into account the 2007 addition of Launch Control, which has been recorded with 0-60 times at 6 seconds stock! DSG shifts faster than a conventional manual, and gets it right EVERY time. So many fantastic advantages to DSG.

 

i don't get it...

so you're saying that DSG > CVT by bringing up an example of a 6-speed manual vs. a 6 speed DSG.

Ok...that's like saying that Burger King burgers are better than McDonald burgers by comparing a burger from Burger King with one from Wendy's.

 

i'm hurt. lol hey i fixed it a couple of post after. give me a break.

 

 

if you don't get it, then I just can't explain it to you!

 

Sorry but a DSG or Manual tranny will always be faster and more powerful than a CVT.

 

your blanket statement shows your ignorance on this subject.

A DSG, manual, or automatic has set gear ratios...ie the tranny has to shift gears during acceleration. A combustion engine has an optimal revolution where it consumes the least fuel and puts out the most power. during acceleration, the engine revs up to the optimal range, passes it, and as the tranny shifts the engine revs drop down below the optimal range and the cycle starts over as the car accelerates.

A CVT does not "shift", therefore the engine can stay as close as possible at the engine's optimal rpm range as the car accelerates. Given a certain car with a certain engine and a manual, auto, or CVT, the CVT theoretically will give the best performance (ie fastest acceleration) with the most efficiency. this may not ring well with "purists" who want a traditional manual tranny, but mechanics is mechanics, physics is physics, and making a statement like "DSG or Manual tranny will always be faster and more powerful than a CVT" is being ignorant of the subject (not to mention that I didn't know trannies were "powerful". last time i looked, engines provide power, not trannies).

current CVT technology has its limitations, but as the technology advances it will soon provide better performance and economy than traditional manuals and autos as well as DSG/SMG transmissions.

 

Again you go back to your name calling. "your blanket statement shows your ignorance on this subject".

The CVT is not as effiecent as you may think. You might do some more research.

http://en.wikipedia.org/wiki/Talk:Manual_transmission

The advantages section considers manuals only against conventional automatic transmissions. CVT's should be considered too, since they fix some of the problems that automatics have and also have advantages of their own. CVT's use clutches rather than a torque converter, and so do away with the disadvantages of that device. Once the car is moving, there is no need to disengage the clutch unless it slows to a near-stalling speed, so these clutches should last a long time! Moreover, regardless of vehicle speed, engine can be run at the optimal RPM. So a CVT should get better fuel economy, and, in principle, better acceleration too. During hard acceleration, the CVT can slowly increase the gear ratio, while the engine stays fixed at its maximum power point.

That is the theory. However, CVT's do not quite deliver on their promise, at least the ones based on a metal V-belt spanning two pulleys. In spite of being in the ideal gear ratio, they have losses which compensate for that gain. See this paper: http://staff.bath.ac.uk/enssa/thesis.pdf Turns out that the belt has some surprising losses. For instance, as the belt goes around the pulley, it has to bend. This makes the V-shaped pieces move closer together on the inside and spread apart on the outside, which causes micro-slip against the pulley, generating heat. So that the belt doesn't actually slip as a whole, there has to be considerable friction on it. The force required to achieve that friction actually distorts the shape of the pulleys. This distortion of the pulley generates heat and represents a loss. Because of that distortion, the belt does not travel in a perfect semi-circular path around the pulleys, which results in more slip. So, a manual transmission is still your best bet for fuel economy. It matters more to have an efficient transmission than to be at some ideally perfect RPM.
Funny, because the Honda Jazz CVT has at worst 2% less fuel economy than the Honda Jazz w/manual transmission. (I heard that in many cases you get better economy with the CVT but I don't have any figures for that right now.) In fact, my 1983 BMW 520i manual lists the automatic transmission as having better fuel economy than the manual gearbox in city driving! That is presumably due to the gear selections in the automatic being better for low-speed acceleration, as well as the "slip" of the torque converter allowing the engine to sit in a more efficient RPM band for longer during acceleration. Therefore I think the claims that manual gearboxes are always more efficient than automatic are wrong. Instead of "5 to 15%" efficiency gain listed, I think "-1 to 15%" would be more correct, to represent that there are cases where automatic transmissions can do better.

 

how is calling your statements ignorant name calling? if it is ignorant, then it is ignorant, plain and simple.

CURRENTLY a CVT is less efficient or worse performing than a traditional manual or manu-matic tranny. But what does tomorrow bring? what innovations or improvements will there be? CVT's were limited to low torque applictaions, but now they are being applied to more powerful engines.

So again, saying that DSG or Manual tranny will always be faster and more powerful than a CVT is ignorant. You want to ignore innovation and advancement, then go right ahead. I'm sure there were a lot of people at GM that said "We will always be more successful than any japanese company" too.

 

Again... I am pretty sure we said POTENTIALLY. Quit reaching, CVTs do provide the ABILITY to be more efficient and more effective than any set ratio transmission. It is really simple physics.

Also, if one wants to say the "V-belt" generates heat, there are many other loss sources in a normal transmission... I'll site the TRANSMISSION COOLER common on many vehicles.

Mike

 

if you read his posts:

he is not open to any other technology's potential to be better than a manual type tranny, no matter how mechanically, physically, or theoretically possible it may be. He also seems to have a hard on for DSG. I'm still trying to understand how a DSG or manual tranny is "powerful". I'm gonna take the tranny off my car and dyno it to see how "powerful" it is.

current CVT technology is not a viable replacement for tradiational trannies in all applications yet (which is why they are still not widely used). But as with any other technology with performance and efficiency potential, it is still developing as more automakers continue use it. And yes, using an absolute like "blahblahblah will always be better" when it concerns constantly changing and improving technology is being IGNORANT.

 

Sorry I know what works in the performance stand point. Please provide links that a CVT is going to be more performance and for best acceleration over a DSG or Manual tranny for that matter.

I have driven a CVT,DSG and Manual all in the same model car and can tell you teh DSG is definitely the faster one to own. Have you? Doubtful.