cvt automatic better for modding?

[johnathanf1lm]

I was looking at cars for my gf when I found the versa which uses a cvt. I do have a general knowledge of cvt and I was wondering ecomodding on a car with a cvt (aero/weight) would increase the fe more than a 6 speed auto. I mean looking at it the lighter/ more Aero body would help the cvt go into a higher gear ratio than before with the same amount of effort.

[MetroMPG]

It does make sense.

If you reduce the load on the engine at cruising speeds (aeromods are your best bet here), the CVT should continue gearing up, where a conventional automatic (or manual) would be stuck with the fixed top gear ratio.

Which is why I wondered why it took so long before I saw someone put a boat tail on a Prius! http://ecomodder.com/forum/showthrea...ail-21455.html

[johnathanf1lm]

Someone agrees woot. I wasn't sure if my theory was right or wrong.

[MetroMPG]

There are of course all kinds of caveats, like what kind of CVT are you comparing to what kind of automatic. EG: a "band" driven CVT still has a maximum top gear ratio by design - you can only get the cruising RPM so low. I'm also not sure about the efficiency of a band-driven CVT vs. a locked torque converter.

But in theory, should work.

[user removed]

Nissan has done some neat things with CVTs, especially in the area of torque converters and overall final drive gearing.

The wifes 06 Murano would accelerate from 0 to almost 70 MPH with the engine RPM pegged on 1700, and was rated to tow 3500 pounds.

My 09 Altima had the torque converter locked up at something like 12 MPH. It worked more like a clutch than a torque converter. It unlocked when shifting from neutral back into "gear" to provide a perfect reengagement.

The latest generations of Nissan CVTs have an added planetary gear set that spreads the range of ratios even higher. I think now it is over 700% between the highest and lowest ratios, which allows for exceptional higher speed lower RPM cruising. They have also worked to reduce internal friction by 40% compared to the earlier models. Service intervals are over 60k miles and they guarantee the transmission for 10 years and 120 k miles.

The newest Altima is rated at 38 MPG highway, same as my 2011 Fiesta.

I could coast in neutral at over 70 MPH, downhill on the Interstate, in my Altima and shift back into drive and the transition was seamless.

I think both the new Sentra and Versa are rated at 40 MPG highway.

regards
Mech

[cRiPpLe_rOoStEr]

I'm extremely favorable to the CVT. Mileage-wise, it's the best option for someone unskilled about stick-shifting.

[capnbass91]

I too am a fan of CVTs, infinite gear ratios is the way to go for efficiency! I look forward to when there are more of them out. I'd love to have a 3 cylinder EcoBoosted Fiesta with a CVT, oh imagine the mileage!

The problem is ignorant drivers, they were taking their cars back because they didn't feel a shift and thought something was wrong. So some CVTs were programmed to make a shift feel, and thus are operating less efficiently. And some people didn't like the "stretching" feeling, which I think is ridiculous, I've driven a Nissan Altima hybrid with a CVT, and it felt fine.

But as said before, if you decrease Cd then it takes less engine power to move the vehicle cruising on the highway, then the CVT could operate at a higher gear ratio, increasing mpg. While a traditional auto tranny is stuck at it's highest gear.

But of course the CVT has a limit to how high of a gear ratio it can go, but it's still an improvement over a regular auto trans.

[Cobb]

Although I hate the sound like a weed eater its nice to always have the right ratio vs several fixed ones for when the going gets tough. I also found that if I go to sport mode and shift to 7th selector and keep the speed around 45 mph I can get some high mpg. Otherwise it seems the cvt loads the engine to 80% and varies the ratio as needed to keep it there in the newer insight.

Id love to be able to flip a toggle switch and have the cvt stuck in over drive when driving on level surfaces at 55 mph. I feel that would help bump up mpg.

[cRiPpLe_rOoStEr]

Originally Posted by capnbass91

I too am a fan of CVTs, infinite gear ratios is the way to go for efficiency! I look forward to when there are more of them out. I'd love to have a 3 cylinder EcoBoosted Fiesta with a CVT, oh imagine the mileage!

That would probably not happen so soon.

The problem is ignorant drivers, they were taking their cars back because they didn't feel a shift and thought something was wrong. So some CVTs were programmed to make a shift feel, and thus are operating less efficiently. And some people didn't like the "stretching" feeling, which I think is ridiculous, I've driven a Nissan Altima hybrid with a CVT, and it felt fine.

Some folks seem to not have anthing better to do than just complain about anything like they're never satisfied