NPP Valve open/close, per mode
#1
Instructor
Thread Starter
NPP Valve open/close, per mode
Folks mention closed, then open exhaust valves at certain RPM; yet no mention of which mode this does that in ?
On another note; what physical changes occur when the 'mode' **** is moved, say from Tour to Sport ? I know the MRC has shock wiring that affects the little micron fluid changes; so, is it a spring rate deal ? Being as non MRC shocks have no such wiring.
Thanks !
On another note; what physical changes occur when the 'mode' **** is moved, say from Tour to Sport ? I know the MRC has shock wiring that affects the little micron fluid changes; so, is it a spring rate deal ? Being as non MRC shocks have no such wiring.
Thanks !
Last edited by RobsCountach`; 03-03-2019 at 10:28 PM.
#2
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In for the answers.
#4
Melting Slicks
Try this and post #18. https://www.corvetteforum.com/forums...post1590304017
Should have all your answers but long.
Should have all your answers but long.
#5
Safety Car
This thread covers the NPP functionality in detail as well:
https://www.corvetteforum.com/forums...ck-result.html
https://www.corvetteforum.com/forums...ck-result.html
#7
Instructor
Thread Starter
Well... I would IF there was a 'Fn' book to read. Being as I'm seeking assistance as a perspective new owner, there isn't one. No need to be rude.
Besides, I doubt very seriously there's an owners manual guide to the physical changes in the spring rate. The posts, some folks were nice enough to post, does
answer the 'when' for the rpms on the NPP. Just looking for the other...
Besides, I doubt very seriously there's an owners manual guide to the physical changes in the spring rate. The posts, some folks were nice enough to post, does
answer the 'when' for the rpms on the NPP. Just looking for the other...
#8
Safety Car
As for the MRC spring rate - it is unchanged by the setting, only the fluid inside the dampers changes. This thread has good spring rate info:
https://www.corvetteforum.com/forums...ing-rates.html
Last edited by JMII; 03-04-2019 at 05:02 PM.
#9
Instructor
Thread Starter
This might help, its from my 2014 manual - the newer cars are slightly different
As for the MRC spring rate - it is unchanged by the setting, only the fluid inside the dampers changes. This thread has good spring rate info:
https://www.corvetteforum.com/forums...ing-rates.html
As for the MRC spring rate - it is unchanged by the setting, only the fluid inside the dampers changes. This thread has good spring rate info:
https://www.corvetteforum.com/forums...ing-rates.html
Hey, appreciate that response. Curious, if the non-MRC cars have no wiring to the shocks, how that **** changes the rate ?
#10
Safety Car
GM MISPRINT ALERT - it should also say "if equipped" in the exhaust section because if you don't have the NPP then the exhaust sounds the same in all modes.
Now keep in mind the steering, exhaust and dash cluster settings can be de-coupled from the **** if you wish. For example you can have the steering on Track all the time with display in Tour all the time while the exhaust is in Sport (model year dependent) regardless of how you twist the ****. The only thing truly locked to the **** is the suspension... well provided you have the mag-ride option. PTM (performance traction management) also requires the mag-ride. It has an additional table shown below:
I was actually surprised to learn that PTM wet and dry didn't use the Track suspension or steering setting. I incorrectly assumed all PTM modes were based on Track until someone corrected me and posted this graphic.
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#11
Instructor
Now keep in mind the steering, exhaust and dash cluster settings can be de-coupled from the **** if you wish. For example you can have the steering on Track all the time with display in Tour all the time while the exhaust is in Sport (model year dependent) regardless of how you twist the ****. The only thing truly locked to the **** is the suspension... well provided you have the mag-ride option. PTM (performance traction management) also requires the mag-ride. It has an additional table shown below:
I was actually surprised to learn that PTM wet and dry didn't use the Track suspension or steering setting. I incorrectly assumed all PTM modes were based on Track until someone corrected me and posted this graphic.
#14
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Folks mention closed, then open exhaust valves at certain RPM; yet no mention of which mode this does that in ?
On another note; what physical changes occur when the 'mode' **** is moved, say from Tour to Sport ? I know the MRC has shock wiring that affects the little micron fluid changes; so, is it a spring rate deal ? Being as non MRC shocks have no such wiring.
Thanks !
On another note; what physical changes occur when the 'mode' **** is moved, say from Tour to Sport ? I know the MRC has shock wiring that affects the little micron fluid changes; so, is it a spring rate deal ? Being as non MRC shocks have no such wiring.
Thanks !
Bill
Last edited by Bill Dearborn; 03-06-2019 at 02:08 AM.
#15
Drifting
The valves will absolutely close on a C7 with a manual transmission even in track mode. I can hear them open close on my 2016. This is called the "hitch". Some people are more prone to hearing it than others. The fact that many people don't hear the change is testament to the programmers. The fact that the valves close was confirmed by Tadge. See the thread referenced above in post #5. From that thread "UPDATE 9/30/2015: I had the opportunity (surreal quite frankly) to meet Tadge and Harlan at a private event today. I spoke privately with the two of them for about 10 minutes, and one of my questions was the NPP programming. Tadge's comment was something like "If we didn't do it that way, we wouldn't be legal". Meaning that even in Track mode, the valves need to close for the dB requirements in the FMVSS pass-by noise regulations."
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#16
Safety Car
Thanks. I find it odd the way GM manages this. The assumption I had was all the PTM modes are Track related... after all the car must be in Track mode to activate PTM, so steering, suspension and exhaust should be in track mode. I could understand the suspension and steering dropping down to maybe Sport mode with PTM Wet to help with traction issues... but Tour? Way too soft for me for track duty. And not leaving the exhaust in Track mode? Oh well.
#17
Melting Slicks
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The spring rate does not / can not change. Leaf springs are non-adjustable. MRC changes the DAMPING rate of the shock absorbers by changing shock fluid viscosity by varying the magnetic field surrounding the fluid.
#18
Instructor
Thanks. I find it odd the way GM manages this. The assumption I had was all the PTM modes are Track related... after all the car must be in Track mode to activate PTM, so steering, suspension and exhaust should be in track mode. I could understand the suspension and steering dropping down to maybe Sport mode with PTM Wet to help with traction issues... but Tour? Way too soft for me for track duty. And not leaving the exhaust in Track mode? Oh well.
[ANSWERED] How do the Various PTM Modes Change Parameters When in Track Mode
PTM was designed exclusively for use on a race track. You are free to make use of these settings on surface roads but that's not what PTM is designed for.
PTM is all about gaining control over the various inter-operable parameters and presenting them in a cohesive step-function format to the race driver
PTM is all about presenting a gradual progression of driver control by progressive disablement of a coordinated set of 'safety' features, while at the same time minimizing the work load on the driver to optimize these individual ***** through trial-and-error.
Sure, the driver is free to experiment. Just don't choose PTM.
To put it bluntly, once you choose PTM, you are operating under 'GM Law'. Just don't fight it. Learn it. Embrace it.
#19
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The valves will absolutely close on a C7 with a manual transmission even in track mode. I can hear them open close on my 2016. This is called the "hitch". Some people are more prone to hearing it than others. The fact that many people don't hear the change is testament to the programmers. The fact that the valves close was confirmed by Tadge. See the thread referenced above in post #5. From that thread "UPDATE 9/30/2015: I had the opportunity (surreal quite frankly) to meet Tadge and Harlan at a private event today. I spoke privately with the two of them for about 10 minutes, and one of my questions was the NPP programming. Tadge's comment was something like "If we didn't do it that way, we wouldn't be legal". Meaning that even in Track mode, the valves need to close for the dB requirements in the FMVSS pass-by noise regulations."
I don't want to argue with Tadge but his engineers did write the description of operation in the Factory Service Manual and he has the disadvantage of being the boss and not necessarily familiar with how the system is actually working. The same way that Dave Hill at the 2004 Corvettes of Carlisle C5 intro told me the C6 Z51 brakes wouldn't fit on a C5 when they would easily adapt.
In large design and development projects the boss is left out of most design details as they have to spend so much of their time on the major items, such as budget, schedule overall design, marketing and running interference against higher up meddling. In most cases the boss isn't even the most qualified person to make design decisions. They just want to know that regulations were followed and don't really care how the regulations were met as long as the cost, schedule and design targets are also met. Miss one of those things and you will be invited to inform the boss what your get well plan is.
Bill
#20
Drifting
I don't know what to tell you Bill. My 2016 manual transmission with NPP, closes per the parameters in the other thread. When Spring get here, I will mount my GoPro so that it is looking at the exhaust and post a video.
I have have pulled the fuse and can hear the difference.
Having been involved in automotive as an engineer and engineering manager for 35 plus years, I can say manual writing falls to the low man on seniority . Mistakes happen.
I have have pulled the fuse and can hear the difference.
Having been involved in automotive as an engineer and engineering manager for 35 plus years, I can say manual writing falls to the low man on seniority . Mistakes happen.