I would have one of it were fixed properly. This one, with cams, tb, headers etc., is expected to make north of 430hp and run out to 76/7700 rpm in a repeated and reliable manner.

 

I am fairly certain the 991.2 in sport plus doesn't shift that fast.

Almost imperceptible in that video, only the change in tone gives it away.

 

It's pretty seamless. Click on the video below of the MXT gearbox in an E36 at the 3:50min mark. You can really hear the straight cut teeth. This is obviously a lot lower RPM application but you get the point. With the Motec ECU the gearbox will be fully customizeable.

https://fb.watch/uFSkr3fsQu/

 

991.2 sport plus shift time at full throttle upshifts from initial torque interruption until full torque is applied in next gear in data I have is 150-200ms, with the shift time itself being around 80-100ms depending on load/torque demand and probably some other stuff I am not seeing. I'm still learning the 991 stuff and it is really complex. There is a lot of stuff going on with matching primary/secondary shaft rpms and limiting clutch slip on the gear changes. The car is still accelerating while it is ramping in so it feels seamless and the torque reduction is tough to notice.

A general guideline I've seen for a starting point of pneumatic sequentials is 50 ms shift time, with 25ms on either end of the shift for torque cut and ramping it back in for 100ms total, and then figuring out what the specific car likes from there.

Going back down the gears on both types of boxes is slightly slower than the upshifts.

 

John, something wrong with the link.

 

Ok, I was off by a factor of ten with the pdk. Oopsie.

50ms, to 100ms, is bloody fast. Going down makes more sense as the engine needs a bit of time to match rpms to gear speed.

I'm impressed you're learning the 991... Admittedly, I have kept it stock (almost, mostly) because I really didn't want to take on another engineering project, but it's very admirable that you're taking the time; will that include how to rebuild them? I think there is a market for that if anyone wants to make the commitment.

The pdk is why I've gone with the extended warranty - Porsche Vancouver has stated that they do not do any type of service on them, save for changing the fluid, and a total failure is simply swapped out, and then sent back to the manufacturer, meaning, very spendy. It doesn't inspire a great deal of confidence with the tuner.... Some go on and on with no problems, other fellas have gone out, started the car, and it was hemorrhaging fluid, on a stock setup.

It seems there is a great deal of sorcery to make them work well beyond what the OEM design requirements were. I've stated before that I am able to confuse it, particularly, in downhill sweepers, left or right, it has a hard time picking the right gear, then bogs down when it hasn't.

I've read mixed reviews on the Cobb tuning, as well as the Dodson clutch pack. I'm not sure how they do it, but if it's anything like what some of the diesel guys are doing, cutting open the tc, modifying the clutch pack, then re welding them, well, they have proven to be less than reliable, especially north of 1000ft/lbs.

So, a 991.2 is I your future...?

 

A tune and a set of downpipes and the thing is in the low 10s / high 9s in the quarter

It is already blazin' fast as is. Do you really need moar power?

 

Finishing up the left/right CSF radiator install.

 

It already does 10.5 in the quarter, but as Chris mentioned, it is way more complex than the 996.

Right when I came on Reenlist, there was a fellow in Australia who had just got one too, but had some pretty bizarre problems with the pdk, and it ultimately just gave up. All stock.

Another fellow running crazy power, no issues.

Maybe, it just needs an exhaust....

 

Nice. Any word on your other project?

 

The PDK is lightning quick, and even with the torque reductions it is never losing acceleration, it is just accelerating with slightly less ferocity.. The sequential gets back to full ferocity a little quicker since it isn't having to deal with clutch protection/rpm matching.

The 991 is an interesting platform. The one I'm working with currently is the 3rd one I've gotten my hands on but the first time I'm getting really technical with all the electronics side of things. My friend has asked me if I wanted to take on more in depth 991 project and lilnked me to a thread in the 991TT section (you know the one) where it seems a lot of people got left hanging but honestly... I'd love to do it, but it would be a learning experience and I barely have time to get anything done on my own car and don't have any of the tooling or the detailed expertise required for engine building. It's not something I'd feel comfortable taking money from people for since I am still learning on the engine/platform and it is also not something I'd do for fun for random people given how busy the rest of my time is between work/life/own car. It is extremely interesting plaform and really fun.

Yes, the PDK is officially not serviceable. It is a sealed unit, no internal parts are sold separately so anything goes wrong even a little leak it is a complete replacement by the book- if you look at the PET trying to find PDK parts, there is just a part number for the whole unit and that is basically it. I've got so many hours in the 991 PET cataloging what parts are shared between TT-GT2RS-GT3RS for the current 991 project and the difference between models is *vast* in the 991 compared to in 996/997- I'm rambling now, so back to topic- There are some shops (True Performance in California is the one that comes to mind) that are doing PDK teardowns and rebuilds, but I am not sure how/where they are getting parts/seals. Seems the common failure point in stock-stockish cars is actually nothing mechanical but an internal sensor, or as you mention above- fluid leak with no replacement seals/parts available.

I have some guesses for what the Cobb PDK tunes do, but without knowing for sure I don't want to speculate too much. I know that they can do something with clutch pressures and torque reductions that take out some of the built in delays can make the overall shift process go quicker (at what cost though? I feel like some of these delays are for reliability purposes). And if you up the clutch pressure a lot to handle increased torque you end up with a car that sucks to drive around at anything less than WOT (another friend is dealing with this issue on higher power stock clutch 991.2 and the supposed fix is the Dodson clutches which allow the clutch pressure to be dialed back down). The Dodson clutches I believe are their own thing, more plates/higher friction material in a basket that replaces the stock clutch basket and won't necessarily quicken shifts or make things more seamless, but it allows to hold more torque with less clutch pressure, or overall more torque at higher pressures. It's a delicate balancing act though, from what I can tell. Interesting how you are able to confuse the PDK. I haven't experienced it yet, but I also am really quick to pull the paddle and get in the gear I want to be in if the car isn't there so I don't really give them a chance to not be where I want to be. I'll pay more attention next time.

Yeah I think a 991.2TTS and keep it closer to stock is in the future for sure. 991.2 aero kit car would be great. I could see doing exhaust for some more sound and some minor suspension changes for the occasional track day/spirited driving, but nothing wild.

 

Realistically, the tune/exhaust 9 sec 1/4 cars aren't doing that on a tune that is every day usable. I was involved with a 991.2TTS with tune/exhaust/drag radial car that went 9.99 @ 139 and backed it up with a 9.97 @ 140 before we got asked to go home for no cage. The tune on that car was aggressive- tuner we worked with told the owner there is some reliability risk with how aggressive it is and dont drive around on this tune- this is for drag strip only and it required race gas. On the "drive it anywhere" and pump gas custom tune, it was 6-7 mph slower trap speed which is huge- not that much slower ET, only 2-3 tenths. But 6 mph is a difference you really notice in how the car feels, and was over a half second difference in 60-130 even though only a couple of tenths in the 1/4.

But yeah, to your point, 10.1-10.2 is still really fast

 

They say the PDK is not serviceable and sealed unit, but there's plenty of people rebuilding them, not to mention the A/M upgrades. It's interesting that BMW ditched the DCT and went back to the 8 speed auto. The 8 speed is very quick too in stock form, kinds mimics the PDK shift speed, though not as good.

 

I think this will be the way with this car; an Inconel exhaust, perhaps some ICs, mild tune, stock turbos - nothing that will raise any suspicion with Vancouver Porsche.

Cheers,

 

When I drove the last new M5 with the 8 speed back to back with my DCT, I could feel the difference immediately. Even with the new AWD system, I found it to be slower to respond in all circumstances than the DCT would. To be fair, that 8 speed had 600hp and mine is a Dinan Stage 2, but the take up with the DCT is superior to any slush box. The addition of AWD also introduced some understeer, which took away from the feel of the RWD only platform, even with being able to disconnect the front diff, the tranny is just not as good.

On the plus side, AWD is excellent in the rain, and if I were to compare that version with this new electron pushing monstrosity, I would take it first.

Cheers,