Greg_STL

I have been watching posts on here comparing the different versions of the Cayman for a while. For full disclosure, I was on the fence about buying a Cayman last year and went to PECLA to drive a Cayman GTS and rented a Cayman GTS on Turo for a day before deciding to buy one. I was worried about a 4 cyl turbo meeting my expectations. My time at PECLA and driving the Cayman GTS on the Pacific Crest Highway let me believe I was more than good with what the GTS offered. I spent several months looking for a used version that had the options I wanted but eventually decided to order the way I wanted.

No sooner did I put my deposit down with my dealer than the production halt happened last summer. Eventually, we figured out that pause was for the factory change and for the switch over to the GTS 4.0. I am still currently waiting for build slot and my dealer has informed me that my deposit would still work for a GTS 4.0. I really have no idea how the Corona virus shut down will impact all of this (beyond me being so bored as to do the analysis that follows).

The *analysis* that follows (and I use that term lightly) was an attempt by me to understand the differences between the Caymans that will b on the market. I basically am comparing the S, GTS 4.0, and GT4. My assumption was at this point that I could not spec out a new GTS 4 cyl car. I certainly could try to find a used one but I went down that path already and decided I wanted to spec a new car. When I get into the manual / PDK comparisons, I reallly just looked between the S and GTS 4.0.

I pulled data from the Porsche US, UK, and international sites to make this table.



I also pulled hp and torque values and gearing ratios so I could compare the three.

718 Power / Torque



GT4 Power / Torque



Gear Ratios For 718. The assumption here is that they are the same for S/GTS/GT4. It think that has been hashed out ad naseum and I assume that to be true for this *analysis*. I'm posting two versions here. The first is from the 718 technical manual that came out very early on in the 718 life cycle and even had warnings that some data would be updated later. The second is from the current web sites. The only difference is in the final drive of the PDK. I believe the web site data is the correct value. I only included the prior numbers because I used the greater number of significant digits when I put all of this in excel.





The final piece of data for the eventual torque/gearing charts is to get data on the tire sizes as those impact the realized final drive ratio. I grabbed data from TireRack for the GTS Pilot Sport 4S and GT4 Pilot Cup 2 tires.





So you notice I only pull data for the S and GT4. I needed an estimate of the GTS 4.0 and I had data from the table that showed the torque was the same but hp was down. Since the formula for hp and torque are linearly related and since we have been told that the GTS 4.0 engine is the GT4 engine with some software changes - I basically just played with the curves in excel until I had something that looked about right. I assumed they would just mess with the torque curve over about 6500 rpm with the software. Do I know that this is true? No I do not. I made an assumption - so again - take all of this *analysis* with a grain of salt or two.

So here are the torque and hp curves plotted at the same scale for the S, GTS4.0, and GT4. I also plot all the way down to zero as I hate it when the marketing departments plot a narrow band and exaggerate the differences. Oh, I kept things in KW and Nm because I didn't want to screw up something when I all I wanted was to compare the different vehicles.





It is interesting to look at these plots. One, the absolute differences in peak torque is amazingly close. I have heard a rumor that there is a torque limit on the manual transmission and these plots tend to validate that as a posibility. The second thing that sticks out to me is just the difference between a low torque turbo and high rev NA engine. I think it is obvious looking at this comparison alone that the two engines would be driven differently. However, gearing still plays a part in all of this but I will look at that in the next post - this one is long enough!

Greg_STL

Putting the hp/torque, gear ratios, final drive ratio and tire sizes all together; I plotted available thrust (lbs) vs. speed (mph). I did conversion here from N-m to lb-ft and I used the revs per mile on the tires and converted to a effective radius in ft. This chart really helps to show the "magic" of gearing. Now I know I'm plotting max throttle torque / hp curves and this does not take into effect mechanical losses, part throttle effects, turbo lag, altitude effect, blah, blah, blah... I know that but it was still fun in my corona virus boredom to plot them and see what it told me.

This first plot shows the Cayman S MT and Cayman S PDK.



Note when you look at it that in first gear the PDK has more available thrust up to ~37 mph. The MT transmission has more thrust available from ~37 mph to ~46mph when the manual has to shift to second. Mind you, there is no time on this plot. The PDK, due to have more thrust available, would reach 37mph faster than the manual. This really says that if you were both going 40 mph and then tried to accelerate that the manual transmission would accelerate faster at that point in time. You will notice on the plot that over the vast majority of the speeds, the PDK has more thrust available. The big advantage under ~37 mph helps explain why PDK 0-60mph times are always faster. It is not just about a faster shift but also due to having better gearing. Also, it is interesting that the MT and PDK have almost the exact same gearing on the MT 6th gear and the PDK 6th gear. Top speed for both is in 6th gear and is listed at 177mph which would be when the thrust matches the mechanical losses/aero drag. The PDK 7th gear is just for better gas mileage and will not give a better top speed.

This next plot shows the GTS 4.0 MT and GTS 4.0 PDK. The GTS 4.0 PDK has been officially stated that it will happen but I am just guessing that it will be the same exact transmission and ratios as the Cayman S. The same things can be seen in this comparison verus the MT vs. PDK as were seen on the Cayman S. The PDK will again be faster especially at lower speeds.



And now for something a little more interesting. How about a comparison between the Cayman S PDK and the Cayman GTS 4.0 MT?



Here you see that the low RPM torque of the Turbo and better gearing of the PDK give the Cayman S PDK a big advantage under 37 mph (and again from 50-60 mph). However, the GTS 4.0 due to its higher torque values at higher RPMs and higher rev range has an advantage at higher speeds. In simple terms; as a daily driver at stop lights, the Cayman S will feel faster. Out on the race track at faster speeds, the Cayman GTS 4.0 will have the advantage.

One last plot for grins - a comparison of the Cayman S PDK to the Cayman GTS 4.0 PDK.



Here, the Cayman S PDK advantage is narrowed down to just under 30mph. Pretty much anywhere above 30mph, as long as the driver is willing to keep the car in the correct high rpm gear - the GTS 4.0 PDK has the advantage. Given that the Sport Plus PDK mapping will probably do that for you - it should not be that hard.

Final thoughts - Each car has its advantages. I haven't even talked about preferences for boxer rumble or boxer wail. If you are a daily driver that never goes to the track - then a Cayman S is a really good fast car that really does not give anything up to its bigger brothers. If you plan to track your car all the time, then the GT4 is definitively the way to go with the better aero and suspension packages. If like me, you plan on dual usage - some daily driving on rough roads with the need for more ground clearance, but still planning to take to the track a couple times a year - then the GTS 4.0 is a very good choice with alot more customization options than the GT4. To me, MT vs. PDK is about preference. The enjoyment might be more with the MT but the speeds are faster with the PDK. I plan on going GTS 4.0 PDK but I really do understand why others would chose something else.

worf928

Whoa! You were bored! Nice job though.

.2PDK

I'm glad your research confirmed why I went with the S.

Well done.

tthellott T

Thanks for spending time on this, great info you put together!

Chester7

Thanks! Great work and nice graphs. In the end, the T4 is a better match for street driving for most drivers. I have a Lotus Elise that requires high RPM to access the power. And I have a 718 GTS. Both are satisfying, but I rarely wind the Elise above 6,000 RPM- so the 718 is the better street car for me.

Dyim

Wow, that’s a detailed analysis.

You must do well with compare and contrast essays in school.

i just go with my gut mostly!

i want a NA engine, manual, and the uniqueness of spyder. Done!

Didn’t worry too much about performance metrics.

Porsch

Great stuff, OP. I’d love to see a video that compares the exhaust note of the three.

AusGTS4.0

With and without GPF would be great

Ubermensch

Nice analysis. I've been thinking about the same thing and expanding my consideration to aftermarket (Deman, Cobb) options as well as 911 variants. If you're willing to share the file (online or directly) I'd be happy to contribute to the effort by populating data for these other options.

Shawn

fueledbymetal

Great info! I'd be curious to see how the 2.5 GTS compares to the 4.0 GTS if you get any more free time...

Greg_STL

Thanks all for the kind words. I will leave the sound clips to someone else. But, I realized I never did post any curves of the GT4. I had never generated curves for the 2.5T GTS in part because I never found kW/Nm curves from Porsche for the 2.5T GTS. The only thing I found was a statement of 420 Nm of torque from 2000 to 5500 rpm and peak power of 269 kW at 6500. I generated a curve based on that text description but I may very well be wrong with how it rolls off. The other funky thing about the 2.5T GTS is that the PDK actually gets a slightly higher max torque value. It is stated at 430 Nm of torque from 2000 to 5000 rpm with the same peak power of 269 kW at 6500 rpm. It does make me wonder that if when the GTS 4.0 and GT4 get a PDK if the max torque might not go up as well. For now, I left 4.0 liter torque curves alone (GTS & GT4).

With those updates, here are the Power and Torque curves for the S, 2.5T GTS Manual, 2.T GTS PDK, 4.0 GTS, and GT4. It is hard to see them individually because they do walk back and forth on top of each other.





I did not want to try to plot lines for 6-7 gears x 4 trim levels x 2 transmissions. I would have been plotting all night in Excel. So instead, I just plotted one line for each trim/transmission combination and took it to the max mph in a gear and then picked up the next higher mph in the next gear. It looks a little odd but it takes out a lot of the data in places where you really should not be driving if you are trying to accelerate as fast as possible. I also did not plot the 7th gear for the PDK. That gear is just for MPG not MPH!

So here are all lines together at once - it is still a bit of a spaghetti plot..



To make it a little more clear - just the manuals:



And now just the PDKs:



And one last one comparing all the GTS models 2.5T and 4.0 N/A with MT and PDK:



My eyes are crossed at this point so I'll let someone else do the comparison and contrast essay. ;-)

Dry Side

I found this in the 718 Brochure for the 2.5T GTS..

Greg_STL

Thanks! I’ll update tomorrow. I’m off but not too bad.

HelpMeHelpU

My thoughts, exactly.