Why don't they use a CVT for the Autos?
10-13-2005, 05:18 PM
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Why don't they use a CVT for the Autos?
I was just wondering why they would never get into using a CVT transmission on the Automatic 8... That way, almost all the energy of the 6 port engine can be harnessed and the 9000 RPM redline would still be there. They have one on the Murano and the Vue and some Subaru had one a while back. The Vue and Murano both produce more HP than the 8, so the HP limitations shouldn't appear to be there, and consider the benefits of a CVT:
1. Higher MPG
2. Less gas emissions
3. Better performance
4. Greater efficiency
Those seem to be issues inherant in the rotary engine, so I would assume that a CVT would be the optimal transmission to pair with it. There will be those that would still want manual, but for those who are buying an automatic, they might as well use a CVT! What am I missing that makes Mazda overlook this?
1. Higher MPG
2. Less gas emissions
3. Better performance
4. Greater efficiency
Those seem to be issues inherant in the rotary engine, so I would assume that a CVT would be the optimal transmission to pair with it. There will be those that would still want manual, but for those who are buying an automatic, they might as well use a CVT! What am I missing that makes Mazda overlook this?
10-13-2005, 06:01 PM
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Originally Posted by zoom44
is there even a cvt in the ford family parts bin for them to even look at?
Generally speaking, cvt trans don't seem to find there way into performance cars mostly economy cars. My niece had a Honda civic cvt and it was a pos. Trans was replaced at least 5 times under warranty. If Honda can't get it right not sure how good a Ford unit will be.
10-13-2005, 06:06 PM
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They would likely have to limit the cvt to 7500rpm or so, like the conventional auto, as I'm not sure how they handle high rpm engines.
audi could only use them for FWD applications due to packaging issues, so I'm not sure if they have a unit that would fit a RWD application. In fact, I can't think of a single RWD car with a CVT. Nissan Murano's can be AWD and have a cvt, but they are much bigger cars/vehicles. DSG is what we really want.
audi could only use them for FWD applications due to packaging issues, so I'm not sure if they have a unit that would fit a RWD application. In fact, I can't think of a single RWD car with a CVT. Nissan Murano's can be AWD and have a cvt, but they are much bigger cars/vehicles. DSG is what we really want.
10-13-2005, 06:11 PM
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Yes, the 500 has an Electronically controlled, continuously variable transmission its automatic transmission option only on the AWD platform however. I find that odd... Additionally, it's CVT has a 2.47 through 0.41 gear ratio while the current AT on the 8 has a 2.785 through 0.694 ratio and the MT has a 3.76 through 0.843 ratio. I'm just floating the idea as I really can't find any cons to it.
Last edited by The RX-8; 10-13-2005 at 06:21 PM.
10-13-2005, 06:34 PM
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you guys should read thru the cvt thread from 2 years ago https://www.rx8club.com/showthread.p...&highlight=cvt and just quote teh posts in that htread that say what you were thinking of posting here :p 
really give it a read good info there that i almost forgot about concerning mazda's cvt and some other interesting info about aisin on the third page
really give it a read good info there that i almost forgot about concerning mazda's cvt and some other interesting info about aisin on the third page
10-13-2005, 06:44 PM
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My sister's ex-boyfriend is a project manager at Ford. According to him, Ford has had CVT's developed for several years. In fact, several of the new tranny's are CVT's. Unfortunately, buyers keep bringing the cars back to the dealer because they think something is wrong since they "won't shift". Ford has actual "wired in" shift points to make it feel like a conventional tranny.
He managed the Escape hybrid and the Zero emission Focus.
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He managed the Escape hybrid and the Zero emission Focus.
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10-13-2005, 07:06 PM
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Originally Posted by agoodcave
Unfortunately, buyers keep bringing the cars back to the dealer because they think something is wrong since they "won't shift". Ford has actual "wired in" shift points to make it feel like a conventional tranny.
10-13-2005, 08:24 PM
#11
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My dad's Ford 500 has CVT and it doesn't have any "wired in shift points". I admit that it's kind of weird driving it without any shift points to reference to but it is smooth. I thought the problem with the RX-8's automatic was that it was the torque converter, not the rest of the transmission, that couldn't stand the high RPM. Ford's CVT still uses a torque converter so that wouldn't help the RX-8.
10-13-2005, 10:16 PM
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Originally Posted by Ericok
My dad's Ford 500 has CVT and it doesn't have any "wired in shift points". I admit that it's kind of weird driving it without any shift points to reference to but it is smooth. I thought the problem with the RX-8's automatic was that it was the torque converter, not the rest of the transmission, that couldn't stand the high RPM. Ford's CVT still uses a torque converter so that wouldn't help the RX-8.
http://www.thecarconnection.com/index.asp?article=5029
Which specifically states this:
Originally Posted by The Article
Torque converters are convenient for drivers, but are inherently inefficient because of the slippage, and this inefficiency makes itself felt in gas mileage.
In place of the torque converter, the Torotrak has a system of two clutches in which the drive is transmitted by variators.
In place of the torque converter, the Torotrak has a system of two clutches in which the drive is transmitted by variators.
ON EDIT: I also found that the Honda Insight's CVT also does not have a torque converter...
http://www.insightcentral.net/encyclopedia/encvt.html
I also find it interesting to note that they mentioned this:
Originally Posted by The Article
Gear Ratio is controlled by a pre-set 3D map with car speed, throttle position, and ideal engine rpm as its 3 axis. The difference between current and ideal engine rpm on the chart is continuously fed back to the ECU. Using linear solenoids, the four-way valves controlling pulley width are activated.
In order to prove useful in all situations, there are three 3D maps the user can select from. In D(rive) mode, the upper power band is avoided, resulting in excellent fuel economy. In S(port) mode, the user can redline the engine.
By using the 3D map control pattern, the Multimatic has the ability to stay in the same power band if/when needed. An example of this is the ability to remain in the high-rpm power band from a standstill to high speed. Because of this, full-throttle acceleration is equivalent to that of a manual transmission. In addition, when traveling at high speeds, because of its ability to infinitely adjust gear ratios, the Multimatic has more passing ability than not only the manual transmission but the conventional automatic transmission using torque converters. With these advantages and the ability to still "shift" to "L" to use the engine brake, there is nothing but advantages.
In order to prove useful in all situations, there are three 3D maps the user can select from. In D(rive) mode, the upper power band is avoided, resulting in excellent fuel economy. In S(port) mode, the user can redline the engine.
By using the 3D map control pattern, the Multimatic has the ability to stay in the same power band if/when needed. An example of this is the ability to remain in the high-rpm power band from a standstill to high speed. Because of this, full-throttle acceleration is equivalent to that of a manual transmission. In addition, when traveling at high speeds, because of its ability to infinitely adjust gear ratios, the Multimatic has more passing ability than not only the manual transmission but the conventional automatic transmission using torque converters. With these advantages and the ability to still "shift" to "L" to use the engine brake, there is nothing but advantages.
Oh and also, for those who talk about semantics, I would like to say that I mean an IVT, not a CVT, since IVT includes neutral and reverse, which a CVT DOES NOT.
Also, I find it funny that the smoothest engine on the road would be paired with the smoothest transmission available. Would that not create the SMOOTHEST CAR TO DRIVE EVER?
Last edited by The RX-8; 10-13-2005 at 10:46 PM.
10-14-2005, 12:24 AM
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I used to drive a CVT civic. From my understanding, the CVT cannot handle too much power without reliability issues.
In short, the CVT is run with a steel belt on 2 pulleys. Its the steel belt that will give way under high loads.
Yup, the CVT is the best transmission ever.
In short, the CVT is run with a steel belt on 2 pulleys. Its the steel belt that will give way under high loads.
Yup, the CVT is the best transmission ever.
10-14-2005, 12:44 AM
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Um I guess I can start claiming which is the best transmission in the world here, so
DSG is the best transmission ever!
on those new VW and Audi cars.
Boy I want it instead of Shiftronic or whatever on my car...
DSG is the best transmission ever!
on those new VW and Audi cars.
Boy I want it instead of Shiftronic or whatever on my car...
10-14-2005, 11:54 AM
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Originally Posted by typej
Um I guess I can start claiming which is the best transmission in the world here, so
DSG is the best transmission ever!
on those new VW and Audi cars.
Boy I want it instead of Shiftronic or whatever on my car...
DSG is the best transmission ever!
on those new VW and Audi cars.
Boy I want it instead of Shiftronic or whatever on my car...
10-14-2005, 12:43 PM
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Originally Posted by Emperor
I used to drive a CVT civic. From my understanding, the CVT cannot handle too much power without reliability issues.
In short, the CVT is run with a steel belt on 2 pulleys. Its the steel belt that will give way under high loads.
In short, the CVT is run with a steel belt on 2 pulleys. Its the steel belt that will give way under high loads.
One other CVT issue that I read about is that the tranny ends up being relatively tall, which wouldn't work well in a car like the RX-8.
10-14-2005, 03:09 PM
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Originally Posted by RevTo9K
For a long time, belts strong enough to handle high power and torque were too expensive to manufacture. Nissan's CVT handles 245 HP and 245 lb-ft in the Murano. However, the Murano's only a couple years old. Long-term reliability issues wouldn't be showing up yet.
One other CVT issue that I read about is that the tranny ends up being relatively tall, which wouldn't work well in a car like the RX-8.
One other CVT issue that I read about is that the tranny ends up being relatively tall, which wouldn't work well in a car like the RX-8.
Also, the DSG should be LESS EFFICIENT than the IVT because the DSG still relies on preset gear ratios, not the infinite ratios that an IVT provides... That means that you cannot achieve optimum efficiency for each and every rpm level.
10-14-2005, 04:02 PM
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Are there and high performance CVT's out there? CVT's are great, but they don't seem suitible for performance cars...yet.
In fact, the prius CVT is designed for POOREST performance(a Toroidal CVT with a few engineering variations to suit the goals of the car)...i remember reading through the eng docs for it some time back and related it to something close to always driving in a gear that is as high as possible while still being able to move the car forward...a clever trick for good gas miliage, but now how i intend to drive my 8.
BTW, is that Ford 500 using a Toroidal CVT?
In fact, the prius CVT is designed for POOREST performance(a Toroidal CVT with a few engineering variations to suit the goals of the car)...i remember reading through the eng docs for it some time back and related it to something close to always driving in a gear that is as high as possible while still being able to move the car forward...a clever trick for good gas miliage, but now how i intend to drive my 8.
BTW, is that Ford 500 using a Toroidal CVT?
Last edited by hedgecore; 10-14-2005 at 04:08 PM.
10-14-2005, 05:47 PM
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Originally Posted by zoom44
why dont people read the info in the link i provided? it doesnt have to be any taller at all.
10-15-2005, 10:28 PM
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Originally Posted by zoom44
why dont people read the info in the link i provided? it doesnt have to be any taller at all.
It's also pretty dated.
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