Nissan GT-R Forum banner
101 - 120 of 120 Posts

·
Registered
Joined
·
2,396 Posts
Discussion Starter · #101 ·
I personally think there is something jacked with the Cobb Software because my results do not seem to correlate with the changes. May have to solicit some help.
 

·
Registered
Joined
·
2,396 Posts
Discussion Starter · #102 ·
More tuning fun today! Just trying to understand how much Clutch Pressure is actually needed to avoid slip. You can see below that I'm running 20bar of line pressure, but if i increase the Clutch Pressure by +50psi (15.1bar to 18.6bar) it doesn't change the amount of slip I'm seeing on the Basket B (3rd Gear). This is 23.5psi so around 750hp/630tq per my dyno results. These are not my final results as I'm just playing around with the pressures to understand what is necessary. BTW, when I tune these clutch pressures I have the CC/TP at 0,0,0,0 because I don't want to rely on these settings to be able to hold the power assuming that I don't run any negative CC/TP values once the tuning is complete. I'll probably end up running about 17-18bar of clutch pressure just to be on the safe side.

Rectangle Product Slope Plot Font



Below is just another random 3rd gear log using the lower pressure numbers, which are essentially the stock numbers in the Torque Table.

Rectangle Slope Plot Font Parallel
 

·
Premium Member
Joined
·
1,833 Posts
If I remember correctly, the clutch slip values that you are seeing are in the normal range. I couldn't find the details in my email but I want to say 125 is when it is considered excessive.
 

·
Registered
Joined
·
336 Posts
Man, I wish I read this thread when I was busy guessing and checking clutch slip before we synced up on my other thread. We were doing a lot of the same trials at similar times and I could have provided the stock comparisons earlier. Anyway, before turbos and FF, I tuned just a midpdipe at 17psi on 91 oct. So maybe 525-550whp and I never got "zero" clutch slip. The bouncing between 5-30 has always been there. For data reference, I had the stage 3 Cobb Tq table in the ECM and their improved shift map in TCM. I did not alter their trans map back then, basically a little line pressure increase at lower TQ's and stock solenoid current. Trans shifted firm and launches were always sub 3 sec on MPSS. Noticeably harder launch (due to press increase). Will start where you are here when I get the Shep stuff installed and let you know how it works.
 

·
Registered
Joined
·
2,396 Posts
Discussion Starter · #106 ·

·
Super Moderator
Joined
·
8,960 Posts
ANY UPDATES?
 

·
Registered
Joined
·
2,396 Posts
Discussion Starter · #108 ·
If I remember correctly, the clutch slip values that you are seeing are in the normal range. I couldn't find the details in my email but I want to say 125 is when it is considered excessive.
Pretty much from what I've seen and read, seeing 40-60rpm is just noise and normal.
 

·
Registered
Joined
·
2,396 Posts
Discussion Starter · #109 ·
Man, I wish I read this thread when I was busy guessing and checking clutch slip before we synced up on my other thread. We were doing a lot of the same trials at similar times and I could have provided the stock comparisons earlier. Anyway, before turbos and FF, I tuned just a midpdipe at 17psi on 91 oct. So maybe 525-550whp and I never got "zero" clutch slip. The bouncing between 5-30 has always been there. For data reference, I had the stage 3 Cobb Tq table in the ECM and their improved shift map in TCM. I did not alter their trans map back then, basically a little line pressure increase at lower TQ's and stock solenoid current. Trans shifted firm and launches were always sub 3 sec on MPSS. Noticeably harder launch (due to press increase). Will start where you are here when I get the Shep stuff installed and let you know how it works.
I don't think you will have an issue tuning the TCM and likely Shep has a base map you can use to get you 90% there. If he doesn't have a map then I would start with the base OEM map or your stage 3 Cobb Tq table and initially tune using your lowest boost setting. It is an iterative intense process and I would advise against just grabbing large chunks of the map and making large global changes. I initially used this approach and it got the WOT tune done quick, but you will inadvertently increase lower TPW torque values that will make the part throttle shifts way too firm. When I read about people with a built trans complaining about harsh shifts, it is because the tuner increased clutch pressure well beyond what was needed for the actual torque being applied.
 

·
Registered
Joined
·
2,396 Posts
Discussion Starter · #110 ·
ANY UPDATES?
I switched over to the "Clutch Torque - Extended TPW" table by selecting it in the "Advanced Engine Parameters" settings.

Rectangle Font Screenshot Parallel Technology



The factory "Clutch Torque" table only allows you to tune up to 25.6ms of TPW, so when you enable the new table it simply allows you to tune for TPW's above 25.6ms. Therefore, once you check this box you need to copy/paste your TPW values and RPM values from the "Clutch Torque" table to the "Clutch Torque - Extended TPW" table and then increase your TPW to whatever you require. In my case, the car runs 32.8ms of TPW so I increased my last value to 33ms as you can see below circled in red.

One note, when you change the torque values in either the "Clutch Torque" table or the "Clutch Torque - Extended TPW" table it makes the change to both tables and in all "Switchable Maps." However, when I changed the TPW axis value to 33ms in "Switchable Map 0," it did not make this change in the other "Switchable Maps" so make sure you rescale the axis in all maps if you make a change.

Font Screenshot Terrestrial plant Software Rectangle
 

·
Registered
Joined
·
2,396 Posts
Discussion Starter · #111 ·
I want to provide clarity for the above post about the "Clutch Torque - Extended TPW" table. There is some confusion about how these tables link so I want to provide additional details.

  1. If you make a change to the table values (not the X or Y axis values), either in the "Clutch Torque" table or the "Clutch Torque - Extended TPW" table, it changes that value for both tables and within all of your Switchable Maps.
  2. When you change the TPW Axis values in one table, it rescales that value in the other table, but only in that specific Switchable Map.

    Example: For Switchable Map 0, when I changed the last TPW axis value to 33ms in the "Clutch Torque - Extended TPW" table, it rescaled that axis value to 8ms in the "Clutch Torque" table. However, it does not change that value in the other Switchable Maps. Therefore, once you rescale the axis values in Map 0, you then need to copy your Map 0 "Clutch Torque - Extended TPW" table to all other Switchable Maps. There is a simple function under "Edit" > "Copy Tables" that allows you to quickly do this.
I'm about to load this changed tune in the car and do some logs to make sure it is working properly.
 

·
Registered
Joined
·
336 Posts
Well how’d it go?


Sent from my iPhone using Tapatalk
 

·
Registered
Joined
·
2,396 Posts
Discussion Starter · #113 ·
Well how’d it go?


Sent from my iPhone using Tapatalk
Works as described. Will post some updates with logs when I get back in town.
 

·
Registered
Joined
·
336 Posts
Figured I'd take your lead on building an extended TPW Clutch torque map while I wait for my trans. The issue is I cannot get lower than 95.4 TPW on the extended map or greater than25.6 on the regular map regardless of if I have the toggle selected or not. I also noticed some weird table limitations in the advanced launch control as well but haven't began to actually tune that one yet. Seems like a bug to me, but wanted a second opinion since you are so well versed in ATR. Am I missing something obvious??
Colorfulness Slope Font Screenshot Parallel

Font Slope Parallel Technology Pattern

Rectangle Product Azure Font Screenshot
 

·
Registered
Joined
·
2,396 Posts
Discussion Starter · #115 ·
Your TPW value on the far right cannot be lower than the values to it's left. Do this, copy the TPW values in the "Clutch Torque" table and then paste them into the "Clutch Torque - Extended TPW" table. Once this is done then you can raise the TPW in the last column to the desired number.
 

·
Registered
Joined
·
336 Posts
Your TPW value on the far right cannot be lower than the values to it's left. Do this, copy the TPW values in the "Clutch Torque" table and then paste them into the "Clutch Torque - Extended TPW" table. Once this is done then you can raise the TPW in the last column to the desired number.
you sir are a damn genius, Thank you! totally worked :)
 

·
Registered
Joined
·
2,396 Posts
Discussion Starter · #117 · (Edited)
you sir are a damn genius, Thank you! totally worked :)
Send me a PM with your email and I'll send you my map in Excel so you can cut/paste to try it. It is based on 20bar line pressure, but regardless is more aggressive vs stock. I'll need to post a graph showing the relationship between MAP and TPW because I run a blow through MAF setup and my MAF scalar is really high, which might slightly skew my TPW values vs a normal tune.

Rectangle Slope Font Parallel Technology
 

·
Registered
Joined
·
336 Posts
Will do, thanks for the help! here is my MAP vs TPW, just using standard 4 bar SD setup with stock MAF scalars. Below is what I came up with for a base tune based on smoothing and acceptable numbers before I had slip. It's a first guess at best, also have sol current at 1.7 to start for my first log but have no issue going to 20Bar. just wanted to creep up on it
Rectangle Slope Plot Font Symmetry

Colorfulness Slope Font Screenshot Parallel
 

·
Registered
Joined
·
2,396 Posts
Discussion Starter · #119 ·
I meant something like the graph below, but all I have are short logs so not enough data to populate the entire curve correctly and especially at very low loads. I went back and compared my stock turbo TPW values before I was on blow through MAF and they didn't seem any different so I suspect you can run my map as is.

Rectangle Product Slope Font Plot



You also need to take advantage of the graphing function in the software and specifically look how the stock Clutch Torque table flowed. Below is the stock table...

Colorfulness Line Font Gas Visual effect lighting



Below is my revised table...

Colorfulness Visual effect lighting Font Gas Technology
 

·
Registered
Joined
·
336 Posts
yep, that's what I meant by "smoothing and guessing" for first iteration..the 3D plot. Here was my first WAG. bet I wind up similar to where you are. thanks
Font Rectangle Gas Slope Visual effect lighting
 
101 - 120 of 120 Posts
Top