Ed@Demonspeed

Is there somewhere that there is a nice write up about what changed between the 991.1 from 2016 and the 991.2 from 2017.

Actually, maybe somewhere where the sum total of differences from year to year from the 996 though present would be nice. If one does not exist, maybe we can add it to the Demon Speed website.


But, back to the 991.1 and 991.2, looking for more than just the broad strokes. Body and engine size, yes, but what about suspension, cooling, gearbox, interior, ... all the details of the changes.

Thanks

Ed

FrenchToast

For general differences I've seen this site: www.gt3r.com , but it isn't for the Cups. I cannot speak to its accuracy.

My understanding is that the biggest difference between the .1 and .2, besides the obvious body changes, is the engine. The .1 uses an engine similar to the outgoing 997.2 cup, while the .2 adopted the new 9A1 evo block. Or whatever the number is.

That said, I don't know much about these cars. I would like to learn some of the differences too. I think I have seen some changes to fastener specs. In the PET some models have a longer bolt at the LCA to upright, which is odd because that would mean the shorter one isn't at full engagement. Maybe it was a typo, never checked.

I think I've seen subtle changes to the cage, but that may have been a GT3R.

A shop that supports a lot of Cup cars might know.

CRex

Hey Ed--

One can compare the two technical manuals till the cows come home. The practical answers from a real driving & competitive standpoint IMO are in the following groups:

1. Engine
- Obvious bit. Much more torquey, enough that after the first year of service Porsche had to update the .2 ECUs to limit revs to 6K at standing starts--because teams and drivers accustomed to launching 991.1s were suddenly killing and replacing clutches every other race weekend LOL...
- Lifing. Extended to 60H between rebuilds. The DFI 9A1 block easily lasts longer if you look at crankcases opened up around the recommended intervals.

2. Front Axle
- Noticeable step up in the .2 through a combination of front aero and different damping, esp. in medium-to-high speed corners.
- Enough to require different driver input, e.g. feathering brakes vs. coasting entering certain high-speed high-load corners such as Shanghai and Sepang S2.

3. Brakes
- Critical differences in the release phase. The optimal pressure curve has shifted from spike-and-release to a more gradual flattish shape.
- Above is moot if one runs ABS but the official series all run without ABS (at least until now) and mastering the brakes is absolutely absolutely critical to driving these cars.
- Braking distance ultimately the same but how the cars get to optimal braking is just entirely different.

4. Bodywork
- Different roof panel.
- New "carbon-skinned" wing (MY19 only).
- Front airdam changes definitely more than just cosmetic.

5. Electronics
- Often overlooked. Cosworth dash has gone through 5-6 evolutions (as recently as Feb 2020, may even after that). Same with PCU. Both software upgradable, just need to go through the exercise.

I do not think it's possible to replicate one with another. But if one is inclined to do a project, I'd start with the dampers and focus on the front axle.

THJR

Ed, if you'd like I can hop on motorsport and screen shot you all the updates PMNA said my 2016 might need (I've done 99.5% of the updates so far)

Off the top of my head (besides the stuff already mentioned and some were mid-run 991.1 updates too)...
• Fire Extinguisher switch
• Foot well foam
• Rear tub/shock tower area bracing (this was def a 991.1 update ~late 14, maybe mid 15?)
• Cosworth Power distro and dashes needed to be send to Cosworth for an update (there is a list of serial numbers. My dash is fine but my power distro fell within the range of serial number that needs an updated SD card or something like that?)
• Rear Brake Cooling Scoop update (uses same tubing - this is just the black plastic piece)
• There was a software update released 05/2020 for 991.1 - ICD,IPS, ECU, DBC - CAN Output
• Not that it matters to club folks like myself but PMNA said the front cooling scoops on the thrust arms can be zipped tied on. (LOL)
• There were some specific P1300 padding requirements that they didn't want you to change/remove pads - found this out when I was looking for Pasha material to redo some of the insets on this stupidly heavy seat. Its a great seat though! (Anyone know where to get flame resistant pasha fabric?!)
• Master Cylinder change for ABS equipped cars (maybe that was a 991.2 update anyway regardless if car is running ABS or not...)
*Some of this stuff might not be a specific change from 991.1 to 991.2 but it would be my assumption that Motorsport would've done all these on the 2017+ cars... still learning 991's myself.

Again, what the other folks mentioned above...
To me the biggest/best changes are obviously the extra grunt from the 4.0 9A1 and the suspension. I just ordered brand new shocks late sept. for my car and there is def a mid-high speed improvement....esp on beat tires (13+ HC on Pirelli DH and it wasn't too bad! haha) With the updated rear springs and what I assume to be newer valving (as least thats what the butt dyno feels) the car just seems more planted. Super Low speed stuff suffered though from the higher rear spring rate... but that could also be me trying to drive it like a short wheel base 997. Due to the abbreviated race season in the north east I only was able to get the car out to 3 events.

There were a few others but I can't remember exactly what. On the road and dictating text so please excuse typos or general sloppiness.
More than happy to send you guys over whatever info I have if it helps!

-Tim

Ed@Demonspeed

Thanks. Great info.

Ed