A base model RC-F comes with the Torsen. The TVD is either a stand alone option or bundled depending on the year. Torsen tested at .95g while the TVD tested at .98g. Seems reasonable. Why in the world would Lexus put the Torsen on the $100K Track Edition with no option for TVD?

 

I think TVD is most suited to less experienced drivers and the Torsen saves weight. IMHO. I love the TVD on the street.

 

They said the focus was on weight reduction and wanted to put the lightest things on it. The TVD unit is heavier than the LSD unit. In the non-TE RCF as there are individual motors on each side of the axle, The carbon fiber roof/spoiler offset 24 lbs of the weight compared to a steel roof LSD RCF, but the TE/FSW RCF focus was on the lightweight and that is why they selected the Torsen. The mechanical Torsen allows for the locking mechanism of the rear axle without the extra weight of the TVD. I personally think it needs Cup 2 tires in order to properly put the power down.

On the flip side, there are inherent advantages of the TVD, which allows for faster cornering speeds as it locks up faster (in less than 1/1000th of a second) and allows the nose response to be sharper because the motors can adjust the torque on the rear axle side-to-side at the same 1/1000th of a second. Also, more weight on the rear axle brings the weight distribution a bit closer to 50/50. That is why it can do close to 1.00g on he skid pad

 

Torsen would be more far a hardcore track purist and possibly Lexus wanted the Track edition to appeal more to that group or at least give the air of a purist. Most of these individuals do not like the feeling of tech intervening. For a highly skilled driver or someone looking to fine tune their driving skill to a razors edge TVD may be numbing as tech is taking some of that experience away.

With Torsen you have to be acutely aware and connected, toying with the limits and balance of the car depending on your driving skill level.
Torsen in a nutshell just has a more mechanical feel with great albeit unforgiving feedback, you have to elevate you game with this diff option. Involves more sensorial adaptation.

For driver skills development it provides a broader scope. You put a driver who has developed their skills on a TVD into a torsen equipped and they will sweat bullets to rein in the car, it's like they have been put on an untamed stallion for the first time. Reverse roles and put one who has developed their skills on a Torsen into a TVD and they may yawn and or be frustrated they can't display their favorite antics with the car. TVD is a gentleman and don't get me wrong very highly capable whereas the Torsen is "in your-face" attitude and demands a lot more from you.

To answer your question as far as the experience goes they wanted to give the Track Edition more of a bite , a bit more of an edge, raw and hardcore.

 

The choice is subjective, but torque vectoring is used in many hardcore track cars like 911 GT3 and exotics like Mclarens, 458 Italia etc. That is totally not how TVD behaves after driving it for 4 years. Lexus sold the TVD as an upgrade in terms of track performance because it was marketed as faster to react as it is faster than what the human hands/legs can do, which makes it more predictable and consistent.

I can oversteer feeding in the throttle so easily especially in 'Slalom' mode, it is mind boggling. The steering off-center makes the front end reacts so instantly with the smallest amount of lock. It actually reacts/locks much faster when detecting traction loss in terms of locking up than a Torsen mechanical LSD. Like I said above, it is far faster than human arms or feet could react at less than 1/1000 th of a second. A human eye can blink in a much slower 1/400th of a second.

It actually makes the car more nimbler, agile and willing to respond faster more easily and more readily. With Torsen, you have to wrestle with the car a lot more (as C&D said below as well). That is why Lexus decided not to put an LSD on the 1-foot longer GSF, the TVD does a great job at hiding its very long wheelbase (which typically works against agility) and size because of the TVD.

Also I mentioned above, TVD RCF also has a 53/47 weight distribution as opposed to 54/46 for the LSD that also is a slight improvement in balance. Again, like I said above, the choice is subjective as some people prefer the simplicity of the Torsen LSD, but the TVD does give advantages in terms of carrying more speed through the turn at the limit.

This has been discussed previously a lot and looks like you missed the conversation. C&D did a back-to-back track test. They put both in the hands of a professional driver and this is what they had to say.




This is a good video of an RCF TVD with fully traction off is so easy to drift and get the tail out whenever he wants to using throttle.

 

There is no doubt TVD can be faster or should I say easier around a race track than one with Torsen. It's all about how you get to the finish line. Some people enjoy the challenge of wrestling with the car. Torsen requires a much higher level of skill and concentration. A lesser experienced driver can do more with TVD.

Torsen requires more seat-time to work out the subtle peculiarities of the RCF's character. That's how I can see reviewers finding Torsen disconcerting they just don't have enough seat time to figure how to manhandle the RCF around the track. For the non-professional who is able to piece it all together its quite an accomplishment and they come out as better drivers from the experience. Requires much more patience and time.

One thing I have wondered and seem to observe casually in photos posted on the Lexus Performance Driving School events it seems they only use Torsen equipped RCF's. If that is so I would imagine they do that to give better driver development, where they can help participants discern how their driving inputs impacts balance of the car. I could be wrong but be interesting for those who have participated to chime in

Torsen is just a different feel. I think for driver skill development it does help sharpen your reflex instincts and feel for the car.

I know you are very passionate about TVD and your perspective is always appreciated.

 

If a car manufacturer wants to make you feel like you have just obtained some super powers and have you smiling from ear to ear they will throw in the TVD. If they want to slap you with a dose of humility they will give you the LSD Torsen option only.

TVD more end-user friendly and still exhilarating.

Torsen, exhilaration only comes after a lot of blood and tears and lucky if you even make it this far, much steeper learning curve.

 

In Lexus driving school I have seen several videos of the carbon/TVD RCF on the slalom exercise. However,cost and availability is another thing to consider since the TVD is part of a more costly carbon option package and majority of the RCFs have LSD on them.




I agree with pretty much everything you said, but the faster lap would be because it is allowing the shortest distance between two points by keeping it tidy and you are not wrestling as much even in the hands of a pro driver (it doing something and then you having to react to inhibit and then spend time correcting it) with the car and it is holding the best and tightest line as much as possible. Randy Pobst for example, called the LSD RCF a "box of chocoloates" around Laguna Seca saying he did not know what to expect as it would be behave differently at every turn. When Randy did the RCF vs M4, Lexus provided him with the Carbon/TVD to run the lap time around the Streets of Willow track.


Lexus press release stated that the TVD makes the RCF behave more like a rear bias weight distribution car as the axis of rotation is shifted towards rear. This graphic gives a much better understanding of how TVD functions through the whole envelope to ensure the car does everything exactly as the driver wants it to

- In the braking zone, TVD applies reverse torque to slow the car down faster (late braking means faster lap time).
- Entering the turn, it applies more torque in the inner rear than outer wheel in order to get the front get a faster turn-in and to inhibit initial understeer.
- Once in the turn, it will quickly shift more torque to the outer wheel to carry the most speed through the turn and sustain the speed with some mild oversteer.
- On the exit, apply equal torque to launch the car out of the turn as quickly as possible.

 

I have a TVD now and have had Torsens in the past. That being said, I agree with most peoples opinion that the Torsen is more predictable. It is my understanding that, along with some weight reduction, the Torsen was chosen for its predictability in the TA. Because the Torsen is mechanical, it always acts the same way under any conditions you expose it to. While the TVD is a great novelty and adds to sense of extra fun, it does, every once in a while, throw you a curveball. That just couldn't be the case with a full blown track car because it will make for inconsistent laps. I like the cool factor of the TVD and it definitely helps a bit in street driving but when I'm tossing the RCF around a parking lot I do wish I had a Torsen so I could get some good clean slides and donuts. The TVD fights a bit too much for traction when really throwing the chassis.

 

You might want to use 'slalom' mode since in my experience it wants to drift on throttle tip-in under tight steering lock at every corner even with reasonably sticky tires I have. 'Track' mode is the one where it will prioritize traction over power slides.

Hardcore track cars these days wanting to maximize traction have torque-vectoring and the best example are the Porsche GT3/GT3 RS 991 generation onwards having torque vectoring. Having said that, to your point when it comes to full on drifting, I would agree LSD would be better as it will give consistent slip angles over something TVD that could be fighting to maximize traction to get more cornering speeds, which is opposite of what drifting is supposed to be doing as you are trying to maximize slip angles at the cost of forward momentum/energy.

The Torsen version of LSD has unpredictability. It might be different for some other LSDs like Giken that are known to be more quick to lock-up than Torsen since Torsen is built to allow more one-wheel spin before it locks-up to split torque equally. The TVD locks up in 1/1000th of a seconds of sensing one-wheel slip so in tests proved to be the more consistent/predictable at least in track timed laps (as the C&D comparison of RCF LSD vs TVD I posted above).

Speaking of that, this is a cool test of an RCF vs M4 in a drift contest. The RCF in the video is not a carbon package, but has a stand-alone TVD. Legend himself Tiff Needell masterfully drifts the RCF