When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Hello my name is Nam and I have a PIWIS addiction. Below is my latest discovery:
From what I understand, when you select the ‘PTV’ option on a build from factory it adds both a mechanical clutch-style LSD and the PTV software. However, the LSD hardware and PTV software are separate entities that simply work alongside each other (https://www.porschefremont.com/porsc...que-vectoring/). The PTV software works through the PSM system to apply a small amount of braking to the inner rear wheel in order to improve to turn-in on corner entry. Whereas the primary job of the LSD is to distribute power on corner exit.
Now I’m not really sure whether you should or shouldn’t activate the PTV software in the absence of a mechanical LSD, and I was hoping to get feedback from experienced drivers. I have seen a few instances of people wanting to disable PTV with concerns of excessive rear pad wear. So at the very least this might offer a solution for those people. This could also be of interest for people who have installed LSDs on cars that came from the factory with open-differentials and wish to add the PTV capability as well.
I’m not sure whether or not I’ll keep PTV enabled because I don’t like the idea of adding additional computer assistance to my driving experience. However, I believe all 991/981 to present GT-products come with PTV as standard and I don’t think I’ve seen much feedback saying that PTV interferes with the driving experience. I will test this out on some twisty roads this weekend and report back. Wish me luck!
Missed that one possibly: Do you have a manual or PDK?
I activated PTV and immediately noticed a difference in tight turns and roundabouts. Going quickly around tight turns I could sense the inside wheel clawing into the ground, helping the car rotate around it and turn in. Compared to before, the car feels more eager to turn in, this was most apparent in roundabouts. Before PTV, the front axle did all the work of turning the car, but now it feels as if both axles are working to turn the car.
As for using PTV alongside an open differential, I don’t think it's necessarily a bad thing. Notably, McLaren adopts quite a similar configuration for most of their lineup. Everything from the McLaren P1 to the 765LT all incorporate an open differential paired with Mclaren’s brake steer system. Here is a video on that system in the P1
In the video, he explains how brake steer can effectively transform an open differential into a quasi-limited slip. Essentially allowing a greater transfer of torque to the ground on the outside wheel compared to the inside wheel, something that is normally impossible on an open differential. Perhaps the same is happening here on our cars? Even if it's not by design.
Regardless, I believe braking the inside wheel can be very effective. For example, if you are kayaking and you intend to turn left, placing your paddle in the water on the left side and using it as a brake is much more effective paddling faster on your right side. This is the same kind of sensation I feel in the car when PTV activates.
I activated PTV and immediately noticed a difference in tight turns and roundabouts. Going quickly around tight turns I could sense the inside wheel clawing into the ground, helping the car rotate around it and turn in. Compared to before, the car feels more eager to turn in, this was most apparent in roundabouts. Before PTV, the front axle did all the work of turning the car, but now it feels as if both axles are working to turn the car.
As for using PTV alongside an open differential, I don’t think it's necessarily a bad thing. Notably, McLaren adopts quite a similar configuration for most of their lineup. Everything from the McLaren P1 to the 765LT all incorporate an open differential paired with Mclaren’s brake steer system. Here is a video on that system in the P1 The McLaren P1 Has An Open Differential?
In the video, he explains how brake steer can effectively transform an open differential into a quasi-limited slip. Essentially allowing a greater transfer of torque to the ground on the outside wheel compared to the inside wheel, something that is normally impossible on an open differential. Perhaps the same is happening here on our cars? Even if it's not by design.
Regardless, I believe braking the inside wheel can be very effective. For example, if you are kayaking and you intend to turn left, placing your paddle in the water on the left side and using it as a brake is much more effective paddling faster on your right side. This is the same kind of sensation I feel in the car when PTV activates.
Great insight! I'd imagine the main difference between the McLaren vs Porsche brake vectoring systems is that Porsche designed their system to work in conjunction with a mechanical limited-slip diff. Whereas McLaren designed theirs to work as a standalone system. So the amount/timing of the rear brake application will vary between the two systems to account for this. This is probably why I didn't notice a huge difference when powering out of corners even with PTV on.
I plan to install a Wavetrac diff this winter. I will report back to how it feels after I get some seat time with it.
Great insight! I'd imagine the main difference between the McLaren vs Porsche brake vectoring systems is that Porsche designed their system to work in conjunction with a mechanical limited-slip diff. Whereas McLaren designed theirs to work as a standalone system. So the amount/timing of the rear brake application will vary between the two systems to account for this. This is probably why I didn't notice a huge difference when powering out of corners even with PTV on. […]
The LSD works only in addition. Initially the torque vectoring AKA brake steer got implemented to avoid mid corner oversteer. Oversteer affected aero and therefore speed. In addition: the better you get the exit line right, the more/the earlier you can work the throttle. It is a matter of exit position and lateral stability. McLaren tells the history in great detail:
The LSD - mechanical or electric - enhances the effect when braking or accelerating in uneven (surface) conditions: it keeps the vehicle in line by adapting the power/torque distribution on the rear axle. (In a Porsche, that is.) But it is in no way directly linked to torque vectoring. Both work completely independently of each other and have different effects.
I always love a good road trip. I wonder if I could fund a trans-america road trip purely on donations from coding a ton of people's cars
Oh I'm sure you could. I've seen tuners on other platforms schedule parking lot gatherings. Dude would get like 10 cars at a time and install preloaded tunes at an Applebees and make a couple grand lol
I've been driving for about two months now and roughly two tanks of gas since enabling PTV. For someone that has zero plans to track the car and enjoys the car on the street, I have really enjoyed the changes to the vehicles turn in and cornering. The car certainly turns in quicker and feels like it rotates better than before. The car is a lot more on its toes and agile now IMO. TBH, the car handles a lot more like I expected and always wanted. Much happier now!
I've been driving for about two months now and roughly two tanks of gas since enabling PTV. For someone that has zero plans to track the car and enjoys the car on the street, I have really enjoyed the changes to the vehicles turn in and cornering. The car certainly turns in quicker and feels like it rotates better than before. The car is a lot more on its toes and agile now IMO. TBH, the car handles a lot more like I expected and always wanted. Much happier now!
Only two tanks?? Those are rookie numbers. By my best guess I'm at about 30 tanks since making the changes and my rear brakes haven't burst into flames just yet.
Only two tanks?? Those are rookie numbers. By my best guess I'm at about 30 tanks since making the changes and my rear brakes haven't burst into flames just yet.
I can help people if you make it to the NY/NJ area. Doing the GT3 steering calibration and PTV are really good. Not that the car was not good before, it’s just better, the car feels more agile and quick.
Only potential negative is a bit more tramlining on bad roads with the GT3 calibration. But that means more feedback.
08-27-2023, 03:00 PM
Wish I lived nearby so I could have you make some adjustments to mine!
