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Ran the numbers for the 6-speed, PDK standard, and PDK with shorter 19" track tires. The tires are 265/35-19 and 305/30-19 and are both 26.3 inches tall vs the stock tires which are 27.0 inches tall. This further reduces the gear ratios by another 2.5%.
Speeds in gears: 1-2-3-4-5 @ 8,000 rpm
6-speed: 50 - 85 - 117 - 146 - 174
PDK-20: 45 - 78 - 108 - 137 - 164
PDK-19: 44 - 76 - 105 - 133 - 160
Those PDK numbers are starting to look pretty good and appear like the car is finally not geared too tall, especially on the 19 inch setup.
If you look at the numbers at 7,000 rpms, as in more typical street driving, then they appear even more like other cars, except we get the bonus of another 1,000 rpms up to 8K.
PDK-19 @ 7,000 rpm: 39 - 66 - 92 - 116 - 140
You can go to the website and run all the numbers you like. These may be off by a mile or two compared to Porsche's official numbers, but they are all based on the same algorithm, so are absolutely relative to each other.
Very cool website. You set your transmission parameters, hit calculate, and all the data pops right up. You can even hit the "shift and trace" button and watch the tagement
Thanks for the web info Rennolazine and Larry Cable.
I think the comparison to look at is a shift point around 6800 which is the max rpm for max torque ... personally I don't think the PDK ratios are short enough compared to the 6MT to make it worthwhile
to lose the engagement of the manual...
The truth is that when compared to the 991.2 GT3 you are one gear lower than the GT4 ...
I agree, kind of surprising they're not shorter. Esp. 2nd and 3rd. Maybe the GT4 PDK will be different somehow.
AFAIK the PDK remains unchanged from the currently available PDK on the rest of the Cayman/Boxster range which are *slightly* shorter than the manual...
I think the comparison to look at is a shift point around 6800 which is the max rpm for max torque ... personally I don't think the PDK ratios are short enough compared to the 6MT to make it worthwhile
to lose the engagement of the manual...
The truth is that when compared to the 991.2 GT3 you are one gear lower than the GT4 ...
I calculated that with the combination of higher torque and shorter gearing, the PDK gives 12% harder acceleration in second gear compared to the manual transmission.
Yes, even shorter gears would be better, but this is what we get. Thankfully it is at least 10-11% shorter. It will make for faster acceleration as the engine winds out more quickly. The shorter tires that I mention of course help as well. Just those tires alone well lower the top speed in gears 1,2, and 3 by 1 mph, 2 mph, and 3 mph respectively. That lowering will not have much affect on a six speed car, but adding those improvements to the PDK, should make the difference between the two cars even more noticeable.
I made a spreadsheet of gear ratios and top speed for most of the 981 and 982 variants. Note that I assume the 718 GT4/Spyder PDK will have the same ratios as the 718 4-cylinder models, but that is not clear, as the PDK specifications for the 4.0L models have not been released.
In the Whichcar interview, Walliser said "We would have loved to have seen that, [the gearing] a little bit shorter, but technically there was no way. We have an answer, which will come later this year and that's very nice then."
He may just be referring to porting the same PDK as the regular 718 models, but I'm curious if he's hinting at a modified version of the PDK. The delay in launching the PDK versions, not announcing the acceleration figures, and the abrupt removal of PDK variant weight and engine torque specs from the US web site all suggest the PDK may not be exactly the same as the version in the regular 718. I wonder if they'll feature a PDK with a shorter final drive than the four cylinder models, or different gear ratios. Having a top speed of 124.8 km/h in second gear is better than the 136.4 km/h of the manual version, but it would be even better if it were say 115 km/h. Shorter PDK gearing would also improve 0-100 km/h and 0-60 mph times, making it much more competitive with the C8 Corvette and Teslas. I'm sure marketing would like that.
Fingers crossed for a shorter final drive or shorter than regular 718 PDK gearing...
If it is just simple math, then by going from 27.0 inch down to 26.3 inch tall rear tires, then we are basically raising the rear diff by 2.66%. So then a final gear of 3.62 x 1.0266 equals a perceived final drive gear of 3.72. Maybe not the 3.89 we would all like, but at least it is something. As a bonus you will end up with wider tires for more grip at the track.
If we were to get a 3.89 rear gear, this is what the gear ratios would look like. The 27.0 inch tires would be the 3.89 and by adding in a 28.3 inch tire to simulate the 3.62 rear gear, you can see both set ups on one page.
I made a spreadsheet of gear ratios and top speed for most of the 981 and 982 variants. Note that I assume the 718 GT4/Spyder PDK will have the same ratios as the 718 4-cylinder models, but that is not clear, as the PDK specifications for the 4.0L models have not been released.
Cool thanks for doing this, can I get either a text or Excel copy of this?
I made a spreadsheet of gear ratios and top speed for most of the 981 and 982 variants. Note that I assume the 718 GT4/Spyder PDK will have the same ratios as the 718 4-cylinder models, but that is not clear, as the PDK specifications for the 4.0L models have not been released.
I actually tested the top speed of each gear of my 981 PDK (up to 4th gear) and it seems like the final drive is actually 3.89 instead of the "official" 3.25 people have found. I remember there being some confusion/controversy about this in old old threads so I gave it a go myself. Given the 718 GT4 MT keeps the same ratios as the 981S MT I would assume the 718 GT4 PDK would have the same ratios as the 981 PDK with a 3.89 final drive.
I actually tested the top speed of each gear of my 981 PDK (up to 4th gear) and it seems like the final drive is actually 3.89 instead of the "official" 3.25 people have found. I remember there being some confusion/controversy about this in old old threads so I gave it a go myself. Given the 718 GT4 MT keeps the same ratios as the 981S MT I would assume the 718 GT4 PDK would have the same ratios as the 981 PDK with a 3.89 final drive.
981S/GTS gear ratios are somewhat different than 981 GT4/Spyder. The 981 GT4/Spyder had taller 5th and 6th gears. The gearing from the 981 GT4/Spyder was carried over to the manual 718 4 and 6 cylinder models.
I drove a 2014 981 PDK base a few years a go, and it felt slow compared to my 987.1 base model. That was probably the long gearing, despite having more power and torque. However, I just watched some videos of 981S PDKs accelerating, and their speedometer to tachometer ratios suggest a 3.62 final drive rather than the reported 3.25. I also read some documentation for the 718 GT4 Clubsport, and it mentioned that it has a 3.25 final drive, but then a constant ratio on top of the final drive too, and those need to be multiplied together to get the effective final drive. So, you’re probably right that it’s not a 3.25 final drive, but rather a 3.62 effective final due to an additional constant ratio before the final drive.
718 4-cyl PDK has a 3.62 effective final drive, but either a 3.89 final drive or different gearing would be great for the 6-cylinder 718 models. I’m hoping this is what the extra development time and wording from Walliser are referring to.
Last edited by wizee; 07-03-2020 at 08:32 PM.
Reason: Did more research
981S/GTS gear ratios are somewhat different than 981 GT4/Spyder. The 981 GT4/Spyder had taller 5th and 6th gears. The gearing from the 981 GT4/Spyder was carried over to the manual 718 4 and 6 cylinder models.
I drove a 2014 981 PDK base a few years a go, and it felt slow compared to my 987.1 base model. That was probably the long gearing, despite having more power and torque. However, I just watched some videos of 981S PDKs accelerating, and their speedometer to tachometer ratios suggest a 3.62 final drive rather than the reported 3.25. I also read some documentation for the 718 GT4 Clubsport, and it mentioned that it has a 3.25 final drive, but then a constant ratio on top of the final drive too, and those need to be multiplied together to get the effective final drive. So, you’re probably right that it’s not a 3.25 final drive, but rather a 3.62 effective final due to an additional constant ratio before the final drive.
718 4-cyl PDK has a 3.62 effective final drive, but either a 3.89 final drive or different gearing would be great for the 6-cylinder 718 models. I’m hoping this is what the extra development time and wording from Walliser are referring to.
It could very well be a 3.62. My "research" was very rudimentary and only involved gunning the engine and looking down at the speedometer. All I knew was that it sure wasn't a 3.25 final drive. The only other documented ratio at the time was 3.89 so I just assumed it was that but what you said makes a lot of sense.
If the final drive has been 3.62 for both the 981 and 718 PDK iterations I kind of doubt they would put in the time and resources to change this in the 718 4.0/GT4.
Last edited by nhnguy12; 07-03-2020 at 08:52 PM.
Reason: Added appropriate dose of skepticism
06-28-2020, 01:18 PM
