The Best Maxima Ever
03-18-2009, 10:31 AM
#41
Senior Member
Join Date: Jul 2003
Location: Central Iowa
Posts: 836
CVTs are more sensitive to certain transient operating conditions.
Here's something I came across, and the material of interest starts midway down.
In addition, I think it's possible to introduce shudder or chatter, neither of which is good for durability. Electronic throttles can easily be dialed back from wide open to part throttle by the PCM, regardless of what the driver's right foot is requesting, so power can be controlled independently of any rev limit setting. All it takes is more lines of code and another lookup table or two.
FWIW, I think torque management is used in at least 1st gear and possibly 2nd in the huge power Mercedes-Benz models, though likely for a different reason.
Norm
Here's something I came across, and the material of interest starts midway down.
In addition, I think it's possible to introduce shudder or chatter, neither of which is good for durability. Electronic throttles can easily be dialed back from wide open to part throttle by the PCM, regardless of what the driver's right foot is requesting, so power can be controlled independently of any rev limit setting. All it takes is more lines of code and another lookup table or two.
FWIW, I think torque management is used in at least 1st gear and possibly 2nd in the huge power Mercedes-Benz models, though likely for a different reason.
Norm
03-18-2009, 02:41 PM
#42
Senior Member
Join Date: Dec 2004
Posts: 1,055
Thanks Bro, that was a great read, especially towards the end when it talks about shorter Service ratios, in fact my car is due for a 9 month service this week.
I was particularly enamoured by this:
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The second lane on the road to improved CVT durability and torque-handling capability is something called integrated drivetrain torque control. While there are steady-state loads on any transmission, it's the transient overloads, or spikes, that could possibly do damage.
Does this absolutely mean that with this quote that Torque Braking in a CVT is detrimental to the Transmission? I don't ever Torque Brake but I know that some ppl who do "Heads up" 1/4 racing do with their automatic transmissions but I've never heard of anyone Torque Braking in a CVT???
Anyone ever heard of anyone Torque Braking their CVT???
03-18-2009, 03:13 PM
#43
Member
Join Date: Dec 2008
Location: Indiana
Posts: 243
"You keep mentioning the governor on these cars but I always thought that the governor on these cars regulated the top speed (limit) and maybe even the Rev Limit but in no form should this affect taking off from a standing start unless you're speaking specifically of the Rev Limiter which doesn't allow our Tach to spin past the 6500 or so limit."
Here is how much one VQ is being held back at low speeds. This is a 350Z with the low speed torque management..ie, governor removed. How about 54 foot lbs at 2k rpm? I first was aware of this last week but have found a lot of info since. Do I feel dumb...yep. I had no idea why the car flies at higher rpm but is sorta average down low.
http://image.sportcompactcarweb.com/...dyno_chart.jpg
Here is how much one VQ is being held back at low speeds. This is a 350Z with the low speed torque management..ie, governor removed. How about 54 foot lbs at 2k rpm? I first was aware of this last week but have found a lot of info since. Do I feel dumb...yep. I had no idea why the car flies at higher rpm but is sorta average down low.
http://image.sportcompactcarweb.com/...dyno_chart.jpg
03-19-2009, 07:02 PM
#44
Member
Join Date: Dec 2008
Location: Indiana
Posts: 243
CVTs are more sensitive to certain transient operating conditions.
Here's something I came across, and the material of interest starts midway down.
In addition, I think it's possible to introduce shudder or chatter, neither of which is good for durability. Electronic throttles can easily be dialed back from wide open to part throttle by the PCM, regardless of what the driver's right foot is requesting, so power can be controlled independently of any rev limit setting. All it takes is more lines of code and another lookup table or two.
FWIW, I think torque management is used in at least 1st gear and possibly 2nd in the huge power Mercedes-Benz models, though likely for a different reason.
Norm
Here's something I came across, and the material of interest starts midway down.
In addition, I think it's possible to introduce shudder or chatter, neither of which is good for durability. Electronic throttles can easily be dialed back from wide open to part throttle by the PCM, regardless of what the driver's right foot is requesting, so power can be controlled independently of any rev limit setting. All it takes is more lines of code and another lookup table or two.
FWIW, I think torque management is used in at least 1st gear and possibly 2nd in the huge power Mercedes-Benz models, though likely for a different reason.
Norm
That is exactly how the Nissan V6 and V8 are "governed" according to bullydog.com who will alter some of the factory settings with their product. At this time the WOT governor removal is available only on the V8 engines. Bullydog refers to the restriction as a governor though that term may confuse us who relate governors to maximum speed or RPM. Some 6th gen racers have had the ECU reflash and the results are outstanding. When I'm out of warranty....maybe.
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