CVT gearboxes.
Discussion
We have a Honda Insight as a pool car, to save burning my own fuel i thought i'd take it home last night.
Well the car itself is pretty awfull, noisy slow, uncomfortable and more worryingly, as it is the reason it exsist, terible on fuel.
WHith much effort and sticking to the limits all the way including around 20 miles at 50mph enforced by average speed cams. 44Mpg, wow, marvellous. My Passat on the same journey does an easy 50mpg +, even the T5 managed 28.
So is the CVT gearbox the reason? I have to confess i rather like the idea, bit odd engine noise due to revs staying fairly constant.
Performance around town is excellent a bit like a scooter really. On motorway at 70mph revs drop right down to around 1800 rpm.
Has any manufacturer used a CVT with a decent engine? I would imagine a diesel would be ideal. An extremely wide range of ratios couild give the low gear getaway combined with ulta low rpm cruising.
After all these things have been used forever on scooters, no matter what your opinion of scooters for the power they do shift.
My personal 180cc with around 16hp will leave most normal cars for dead up to around 60, way quicker than the power should do, 0 - 60 around 7 seconds i seem to recall.
Well the car itself is pretty awfull, noisy slow, uncomfortable and more worryingly, as it is the reason it exsist, terible on fuel.
WHith much effort and sticking to the limits all the way including around 20 miles at 50mph enforced by average speed cams. 44Mpg, wow, marvellous. My Passat on the same journey does an easy 50mpg +, even the T5 managed 28.
So is the CVT gearbox the reason? I have to confess i rather like the idea, bit odd engine noise due to revs staying fairly constant.
Performance around town is excellent a bit like a scooter really. On motorway at 70mph revs drop right down to around 1800 rpm.
Has any manufacturer used a CVT with a decent engine? I would imagine a diesel would be ideal. An extremely wide range of ratios couild give the low gear getaway combined with ulta low rpm cruising.
After all these things have been used forever on scooters, no matter what your opinion of scooters for the power they do shift.
My personal 180cc with around 16hp will leave most normal cars for dead up to around 60, way quicker than the power should do, 0 - 60 around 7 seconds i seem to recall.
Hybrids are only really 'economical' in town driving. On country roads and motorways you are not doing much regenerative braking so the car has to run purely off its petrol engine whereas in town there is a lot more stopping and coasting involved which recharges the battery using the kinetic energy from the cars motion.
My FIL's Lexus GS450h does 40mpg+ round town (not bad for a 3.5 litre engine) and 0-60 in 5.7 seconds making it quicker than the V8 that is also available in the same car and cheaper to run (fuel-wise) than most diesels (My Scenic diesel does around the same to the gallon round town but of course diesel is (usually) more expensive to buy!). On a run however it drops into the low 30's.
ETA - his car also has the CVT gearbox and it is really weird to listen to the engine!
My FIL's Lexus GS450h does 40mpg+ round town (not bad for a 3.5 litre engine) and 0-60 in 5.7 seconds making it quicker than the V8 that is also available in the same car and cheaper to run (fuel-wise) than most diesels (My Scenic diesel does around the same to the gallon round town but of course diesel is (usually) more expensive to buy!). On a run however it drops into the low 30's.
ETA - his car also has the CVT gearbox and it is really weird to listen to the engine!
Edited by flakeypaul on Sunday 26th December 11:56
every now and then there is a flurry of news from torotrak about its 'IVT' then it all goes quiet
http://www.torotrak.com
http://www.torotrak.com
Many manufacturers have been using CVT for years they were even in Ford Escorts and Fiestas.
My wife's Audi A6 TDi has one.
They have a reputation for breaking on the internet but its simply because there are so many around IMO.
I think they are great, hers has '6 gears' selectable on the steering wheel too.
BUT the problem with CVT is that they don't have torque convertors hence its hard to make a fast getaway from junctions.
I tend to floor it a second before I need to move then lift up my foot when the wheels start to move. I don't find it a problem but people who borrow it all complain about the initial delay.
My wife's Audi A6 TDi has one.
They have a reputation for breaking on the internet but its simply because there are so many around IMO.
I think they are great, hers has '6 gears' selectable on the steering wheel too.
BUT the problem with CVT is that they don't have torque convertors hence its hard to make a fast getaway from junctions.
I tend to floor it a second before I need to move then lift up my foot when the wheels start to move. I don't find it a problem but people who borrow it all complain about the initial delay.
Should have googled first, apparently Williams tried it in F1 but was banned for being to quick.
I'm liking the idea more and more, surely this has the potential to be quicker and more economical too.
Highest ration could be monstrous, not much over tickover at cruise and yet engine at peak throughout the whole acceleration phase.
I'm liking the idea more and more, surely this has the potential to be quicker and more economical too.
Highest ration could be monstrous, not much over tickover at cruise and yet engine at peak throughout the whole acceleration phase.
CVT transmissions you say?
In the right application, they rock;)
http://www.masseyferguson.com/EMEA/GB/products/tra...
In the right application, they rock;)
http://www.masseyferguson.com/EMEA/GB/products/tra...
JPJPJP said:
every now and then there is a flurry of news from torotrak about its 'IVT' then it all goes quiet
http://www.torotrak.com
How many years has this been in development and never reached production. I lived near the place that was developing it but have never heard of it in the market place yet.http://www.torotrak.com
Nissan seem to be the most experienced with CVT's for larger engines, especially with the Murano. They also seem to have a good reputation for durability, which other manufacturers don't seem to have nailed yet.
I love driving CVT's, if properly done they really let you get the best from a car and don't get in the way of the business of going around corners. You always have maximum power available, the car is never disturbed mid-corner, you never run out of revs and most systems give you decent amounts of engine braking.
In my opinion potentially the best of the lot is the Toyota/Lexus 'not really CVT' in the hybrids. Super simple, seemingly very reliable and scalable for any size of engine unlike belt-driven systems which are often torque limited.
I love driving CVT's, if properly done they really let you get the best from a car and don't get in the way of the business of going around corners. You always have maximum power available, the car is never disturbed mid-corner, you never run out of revs and most systems give you decent amounts of engine braking.
In my opinion potentially the best of the lot is the Toyota/Lexus 'not really CVT' in the hybrids. Super simple, seemingly very reliable and scalable for any size of engine unlike belt-driven systems which are often torque limited.
Ozzie Osmond said:
It is rarely that I find no appeal whatsoever in an entire category of transmission but CVT is it. All the ones I've driven have been utterly hateful. Useful only IMO for people who don't like driving and don't like cars.
Since we seem to represent opposing views, what do you find hateful about them?Ozzie Osmond said:
It is rarely that I find no appeal whatsoever in an entire category of transmission but CVT is it. All the ones I've driven have been utterly hateful. Useful only IMO for people who don't like driving and don't like cars.
This sounds like the words from someone who believes that you should only have a manual gearbox in a performance car.The_Burg said:
Has any manufacturer used a CVT with a decent engine? I would imagine a diesel would be ideal. An extremely wide range of ratios couild give the low gear getaway combined with ulta low rpm cruising.
Audi have done V6's and Turbo charged 4cyls (called Multitronic) but on the later models they did away with the CVT mode (ie no ratios at all, just like a scooter) and made it operate like a normal auto with 6 'ratios'.Bit silly and misses the point of CVT I think.
We have 1,3 83bhp Honda Jazz CVT that has various modes - you can use it as just CVT or press a button and it shifts according to 7 ratio's like an auto and with paddles for manual control. It also has an 'S' mode for a higher ratio when in CVT mode which is good when you want more punch.
Initially I found it horrible but as it is really the wifes car we kept it and now that I have used in allot of traffic I have to say it is great transmission and makes a small engine seem torquier than it is. The thing is you need to get to know how to use it to see best performance. When really pressing on it is better to use the 'manual' ratios but for around town in CVT mode it is great and makes progress at low revs that is hard to imagine in a puny 1,3 petrol.
I would love to try a 'performance' CVT but I think that won't happen anymore - DSG looks to be the way forward now for most manufacturers with CVT being put into eco cars only.
Edited by Dino D on Monday 27th December 11:19
AnotherClarkey said:
Since we seem to represent opposing views, what do you find hateful about them?
I guess it's two things. Firstly I've never got comfortable with the driving experience of rpm changing independently from road speed. Secondly, the CVT system isn't good at handling any significant amount of torque in a road car and the transmissions tend to get used with small engines which, in truth, are probably not well suited for an auto application. Overall the result ends up to my taste as "transportation" rather then "driving".Eagerbeaver said:
This sounds like the words from someone who believes that you should only have a manual gearbox in a performance car.
Sounds like, but strangely isn't. IMO an auto can work well in a fast car. Especially a well-made auto which is sensitive to driver inputs and has the sense not to change gear mid-corner. Decent manual over-ride (whether flappy paddle or conventional lever) completely avoids the dcreaded kick-down delay.At the end of the day I entirely accept all of this is personal taste. CVT simply hasn't pushed my buttons.
The_Burg said:
Has any manufacturer used a CVT with a decent engine? I would imagine a diesel would be ideal. An extremely wide range of ratios couild give the low gear getaway combined with ulta low rpm cruising.
My inlaws have a Merc A180 diesel with the CVT. It does work extremely well, pretty much as imagined by the OP. It is also particularly good in the mountains. The only real downside is that the engine itself is very agricultural.Like Ozzie said, they don't seem to like big torque which keeps them away from decent turbo-diesels.
Another biggie is that your average driver is going to get freaked out by the way it works - the lack of distinct ratios, its gonna feel like an autobox with a slipping converter. Hence why a lot of the ones in use pretend to be autos by having the distinct ratios programmed into them.
Another biggie is that your average driver is going to get freaked out by the way it works - the lack of distinct ratios, its gonna feel like an autobox with a slipping converter. Hence why a lot of the ones in use pretend to be autos by having the distinct ratios programmed into them.
Ozzie Osmond said:
I guess it's two things. Firstly I've never got comfortable with the driving experience of rpm changing independently from road speed. Secondly, the CVT system isn't good at handling any significant amount of torque in a road car and the transmissions tend to get used with small engines which, in truth, are probably not well suited for an auto application. Overall the result ends up to my taste as "transportation" rather then "driving".
Agree with that and the reasons you hate is the reasons I love it - it is for transportation, not driving. Around town it is great and makes very smooth progress with no gear changes and keep revs low so a horrible engine (like the thrashy 1.3 I have it attached too) is not heard and not extended into it's noisy zone.It is great transmission for town and general transportation but not for 'driving'. As most of my driving nowadays involves just getting around in town (and with you kids on board) my driving style has changed accordingly and the CVT suits this. Make smooth (but not dead slow) driving a doddle.
The way engine speed is linked to road speed is so hard-wired into our driving culture it is true that anything else seems odd and unsatisfying. I suppose I feel that, nice though the noise is, it just highlights the inefficiency and compromise inherent with fixed ratio transmissions. As soon as you arrive at the point where the engine is giving you maximum power you have to completely disengage the drive and drop the revs to a point where it is delivering substantially less - then repeat.
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