Notices
C8 General Discussion The place to discuss the next generation of Corvette, be it mid-engine, Zora, or whatever form it may take.
Sponsored by:
Sponsored by:

DCT Power-Brake Question

 
Old 01-16-2019, 06:13 AM
  #1  
Perf n Restore
CF Senior Member
Thread Starter
 
Member Since: Apr 2007
Location: Poughkeepsie NY
Posts: 449
Thanked 155 Times in 67 Posts
Default DCT Power-Brake Question

For those familiar with the DCT:
Can you "power brake" a DCT?
I recognize that the DCT does not have a torque converter that you could power brake for a launch.
So...how would a DCT perform the same power brake?
Standing still, with the DCT in "D" or "1" the clutch is disengaged.
If you have foot on brake and gas, what will happen as opposed if same is done with A8?
Perf n Restore is offline  
Old 01-16-2019, 07:52 AM
  #2  
JoesC5
CF Senior Member
 
Member Since: Sep 1999
Location: Springfield MO
Posts: 39,822
Thanked 1,294 Times in 935 Posts
Default

Sort of..... depending on the brand, you can place your left foot on the brake, then floor the accelerator with your right foot. Then wait for the RPM to stabilize at 4,000 RPM. Remove your left foot off the brake pedal and off you go.

When you are holding the brake pedal with your left foot and the engine RPM's are at 4,000 RPM's, it takes no more force to hold the brakes then if you were holding the brakes with a manual transmission while holding the RPM at 4,000. RPM. No power braking required, as the clutch is not transferring any power to the transmission until you actually release the brake and then the car's computer engages the clutch, automatically.

The car's computer modulates the DCT's 1st gear clutch for beat acceleration.

Last edited by JoesC5; 01-16-2019 at 07:56 AM.
JoesC5 is offline  
The Following User Says Thank You to JoesC5 For This Useful Post:
Perf n Restore (01-16-2019)
Old 01-16-2019, 08:12 AM
  #3  
Chrisrokc
CF Senior Member
 
Chrisrokc's Avatar
 
Member Since: Mar 2003
Location: Oklahoma City OK
Posts: 1,437
Thanked 42 Times in 16 Posts
Default

You can, but you shouldn't need to. I have power breaked my Macan just to see. In compression to the launch control, it is not worth it. Launch control revs to 4-5k rpms and dumps it.
Chrisrokc is offline  
Old 01-16-2019, 09:06 AM
  #4  
TheSenator
CF Senior Member
 
TheSenator's Avatar
 
Member Since: Sep 2015
Location: Houston Tx
Posts: 139
Thanked 36 Times in 24 Posts
Default

+1 Launch Control (electronic). This how my GR6 works.
Hold brake all the way down.
While holding brake, hammer gas pedal to 100%.
Here is where the ECU will recognize you're attempting a launch, and will slip the clutches, while building to preset RPM.
Next, dump the brake pedal.
Profit.
TheSenator is offline  
The Following User Says Thank You to TheSenator For This Useful Post:
Perf n Restore (01-16-2019)
Old 01-16-2019, 09:38 AM
  #5  
ByByBMW
CF Senior Member
Support Corvetteforum!
 
ByByBMW's Avatar
 
Member Since: Dec 2004
Location: AZ
Posts: 5,083
Thanked 107 Times in 62 Posts
St. Jude Donor '06-'08-'10-'11-'12-'13 '14-'15-'16-'17

Default

On my Boxster, I place the system in Sport+ mode, hold the brake and floor the go pedal. The computer notes that a "launch control" is wanted. Revs go to the Rev limiter and when the brake is released, the computer controls wheel spin, revs etc to effect a launch with the least wheel spin with max power/acceleration. Road and Track did a "torture test" on a PDK equipped 911, 50 back to back runs with no cooldown in an attempt to "break" the system. They gave up after 61 back to back runs. Here is the video. https://www.youtube.com/watch?v=A5DR...ature=youtu.be
ByByBMW is offline  
The Following 3 Users Say Thank You to ByByBMW For This Useful Post:
firstvettesoon (01-16-2019), Perf n Restore (01-16-2019), Tool Hoarder (01-16-2019)
Old 01-16-2019, 10:28 AM
  #6  
Perf n Restore
CF Senior Member
Thread Starter
 
Member Since: Apr 2007
Location: Poughkeepsie NY
Posts: 449
Thanked 155 Times in 67 Posts
Default

So based on the above comments, it looks like there is no way to do a smoking burnout.
The ecu will control wheel spin?
Perf n Restore is offline  
Old 01-16-2019, 10:28 AM
  #7  
vetteLT193
CF Senior Member
Support Corvetteforum!
 
Member Since: Jul 2002
Location: Tallahassee fl
Posts: 1,312
Thanked 92 Times in 62 Posts
Default

On my M3 you can hold the brake, floor it, and it does a quasi launch control where it will rev to 4000ish.... if you go through a stupidly complex series of steps you can put it in actual launch control. In real mode once it is engaged you end up flooring it with the paddle pulled and foot off the brake. It revs to 5500 or so, let go of the paddle and it goes and does everything else for you shifting included.
vetteLT193 is offline  
The Following User Says Thank You to vetteLT193 For This Useful Post:
Perf n Restore (01-16-2019)
Old 01-16-2019, 10:40 AM
  #8  
ByByBMW
CF Senior Member
Support Corvetteforum!
 
ByByBMW's Avatar
 
Member Since: Dec 2004
Location: AZ
Posts: 5,083
Thanked 107 Times in 62 Posts
St. Jude Donor '06-'08-'10-'11-'12-'13 '14-'15-'16-'17

Default

Originally Posted by Perf n Restore View Post
So based on the above comments, it looks like there is no way to do a smoking burnout.
The ecu will control wheel spin?
If I invoke launch control, it won't do a smoky burnout. I have not tried it in normal/non launch control but at my power levels, I doubt I could do a smoky burnout. The tires have enough traction at my power levels that a smokey burnout is unlikely.
Keep in mind this is Porsche's programming and really can't be compared to anybody elses DCT control.

Last edited by ByByBMW; 01-16-2019 at 10:41 AM.
ByByBMW is offline  
Old 01-16-2019, 10:56 AM
  #9  
TheSenator
CF Senior Member
 
TheSenator's Avatar
 
Member Since: Sep 2015
Location: Houston Tx
Posts: 139
Thanked 36 Times in 24 Posts
Default

Assuming RWD only and no line lock, it would kind of be the opposite sequence if you wanted a burnout.
Traction control OFF
Hammer the gas pedal.
Immediately stomp the brake.
No launch proceeds to burnout.
M3 and 911 guys can confirm?

The GTRs buy AWD electronic controllers, to tell the trans and ETS where to send power, and disable launch control.
This is how you see GTRs do burnouts at the strip.
TheSenator is offline  
Old 01-16-2019, 11:05 AM
  #10  
Chrisrokc
CF Senior Member
 
Chrisrokc's Avatar
 
Member Since: Mar 2003
Location: Oklahoma City OK
Posts: 1,437
Thanked 42 Times in 16 Posts
Default

Originally Posted by TheSenator View Post
Assuming RWD only and no line lock, it would kind of be the opposite sequence if you wanted a burnout.
Traction control OFF
Hammer the gas pedal.
Immediately stomp the brake.
No launch proceeds to burnout.
M3 and 911 guys can confirm?

The GTRs buy AWD electronic controllers, to tell the trans and ETS where to send power, and disable launch control.
This is how you see GTRs do burnouts at the strip.
That will work. Itís not unsimilar to how I would do a burn out in a current corvette auto or stick.
Chrisrokc is offline  
Old 01-16-2019, 11:24 AM
  #11  
Shaka
CF Senior Member
 
Shaka's Avatar
 
Member Since: Nov 2002
Location: FLL Florida
Posts: 2,516
Thanked 351 Times in 233 Posts
Default

Originally Posted by Perf n Restore View Post
For those familiar with the DCT:
Can you "power brake" a DCT?
I recognize that the DCT does not have a torque converter that you could power brake for a launch.
So...how would a DCT perform the same power brake?
Standing still, with the DCT in "D" or "1" the clutch is disengaged.
If you have foot on brake and gas, what will happen as opposed if same is done with A8?
All depends on the logic in your car's ECM. Learn your car's DCT logic. You must learn how to drive a specific DCT. The engineers can't design for every contingency. They are continuously being improved. Each manufacturer has a different set up. It has never been a good idea to slip a stick shift Corvette clutch on launch, it is either in or out. Torque converters can handle high stall speeds but it sure raises temps in a hurry. DCTs are a different story.
When you hold your foot on the brake and add gas, the ECM detects no forward speed and won't allow clutch to engage. Launch control raises the RPM to what the manufacturer determines and engages the clutch when the brake is released. Only Porsche PDKs can handle continuous abuse. Some of the things the ECM has difficulty with is upshifting when slowing down or downshifting when accelerating. Short shifting is great with a stick shift to control torque in a turn exit. I changed my cam in my roadster, not for more power, but lower torque at low rpms. Now everything is done with a computer but you must assist it with knowledge. For instance, if you are on an incline at a stop, keep your foot on the brake to keep the clutch dis engaged. creeping in traffic especially on a hot day, keep pulling both shifts to let the car roll in neutral on early cars. Watch for high clutch temps.
I don't know what car you have, but hold the brake and add gas. Watch RPM. It might rise and fall while the ECM figures out what you are doing. Try it in LC and D. Ask the question on your cars's forum.
Shaka is online now  
The Following 3 Users Say Thank You to Shaka For This Useful Post:
firstvettesoon (01-16-2019), Perf n Restore (01-16-2019), PHILLIP YOUNG (01-16-2019)
Old 01-17-2019, 11:12 AM
  #12  
Houston Z33
CF Senior Member
 
Member Since: Aug 2013
Location: Houston TX
Posts: 420
Thanked 12 Times in 6 Posts
Default

Power Braking on any DCT is shaving life those clutches in good amounts, Brake Boosting is another way to kill a DCT.
Houston Z33 is online now  
Old 01-17-2019, 02:06 PM
  #13  
jefnvk
CF Senior Member
 
jefnvk's Avatar
 
Member Since: Nov 2018
Location: AA/Metro Detroit
Posts: 376
Thanked 108 Times in 68 Posts
Default

Use launch control. Problem solved.

Lots of performance cars these days offer line lock if you really want to do burnouts: https://jalopnik.com/all-ford-mustan...car-1796526813
jefnvk is online now  
Old 01-17-2019, 02:27 PM
  #14  
Shaka
CF Senior Member
 
Shaka's Avatar
 
Member Since: Nov 2002
Location: FLL Florida
Posts: 2,516
Thanked 351 Times in 233 Posts
Default

Originally Posted by jefnvk View Post
Use launch control. Problem solved.

Lots of performance cars these days offer line lock if you really want to do burnouts: https://jalopnik.com/all-ford-mustan...car-1796526813
Each manufacturer has an abuse clause in the small. print. Abuse can be verified easily because it is retained in the car's computer. The cars brains can find you guilty and sentence you by not honoring the warranty. No ****.
Every time you switch on TC or switch off VDC, they are watching you. The GPS tells which track or drag strip you're at. The C8 will have similar algorithms. The GTR will go .2 of a second slower if you just stomp on the gas. The Nissan police will let you go free, IE: if you don't have a clutch job before 200 miles is up,
Shaka is online now  
Old 01-17-2019, 02:32 PM
  #15  
jefnvk
CF Senior Member
 
jefnvk's Avatar
 
Member Since: Nov 2018
Location: AA/Metro Detroit
Posts: 376
Thanked 108 Times in 68 Posts
Default

Originally Posted by Shaka View Post
Each manufacturer has an abuse clause in the small. print. Abuse can be verified easily because it is retained in the car's computer. The cars brains can find you guilty and sentence you by not honoring the warranty. No ****.
Every time you switch on TC or switch off VDC, they are watching you. The GPS tells which track or drag strip you're at. The C8 will have similar algorithms. The GTR will go .2 of a second slower if you just stomp on the gas. The Nissan police will let you go free, IE: if you don't have a clutch job before 200 miles is up,
Seems to me if they are that interested in your line lock usage, they'd quickly be able to detect power braking, drag racing, and burnout situations without switches, too.

Last edited by jefnvk; 01-17-2019 at 02:32 PM.
jefnvk is online now  
Old 01-17-2019, 04:51 PM
  #16  
NY09C6
CF Senior Member
 
NY09C6's Avatar
 
Member Since: Sep 1999
Location: Texas
Posts: 6,620
Thanks: 0
Thanked 188 Times in 131 Posts
Default

Some manufactures void the trans warrantee for launch control usage or limit the number of times it can be used.
NY09C6 is offline  
Old 01-18-2019, 10:43 AM
  #17  
ByByBMW
CF Senior Member
Support Corvetteforum!
 
ByByBMW's Avatar
 
Member Since: Dec 2004
Location: AZ
Posts: 5,083
Thanked 107 Times in 62 Posts
St. Jude Donor '06-'08-'10-'11-'12-'13 '14-'15-'16-'17

Default

Originally Posted by NY09C6 View Post
Some manufactures void the trans warrantee for launch control usage or limit the number of times it can be used.
Do you have some links or other info as to which manufacturers void those warranties?

ByByBMW is offline  
Old 01-18-2019, 02:46 PM
  #18  
NY09C6
CF Senior Member
 
NY09C6's Avatar
 
Member Since: Sep 1999
Location: Texas
Posts: 6,620
Thanks: 0
Thanked 188 Times in 131 Posts
Default

Originally Posted by ByByBMW View Post
Do you have some links or other info as to which manufacturers void those warranties?
Nissan with the GTR is the one that comes to mind. BMW has warnings to limit its use due to excessive wear and tear.
NY09C6 is offline  
Old 01-18-2019, 04:14 PM
  #19  
Sub Driver
CF Senior Member
 
Member Since: Aug 2015
Posts: 609
Thanks: 0
Thanked 264 Times in 155 Posts
Default

Originally Posted by NY09C6 View Post


Nissan with the GTR is the one that comes to mind. BMW has warnings to limit its use due to excessive wear and tear.
Nissan does not void warranty for using launch control. Using launch control is completely warrantied since 2012. The issue was for the 2009-10 models where people decided to turn off VDC mode, which is explicitly prohibited in the owners manual, to try to launch the car because it was providing quicker 0-60 times. The GTR does limit the number of launches when the transmission gets too hot.
Sub Driver is offline  
The Following User Says Thank You to Sub Driver For This Useful Post:
ByByBMW (01-18-2019)
 


Thread Tools
Search this Thread
Quick Reply: DCT Power-Brake Question


Sponsored Ads
Vendor Directory

Contact Us - About Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
 
  • Ask a Question
    Get answers from community experts
Question Title:
Description:
Your question will be posted in: