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Link? Narrowbody or C4S only? I presented information on the assumption that the 40th AE was the best possible 996 Carrera for AX, which was 8&10. C4S is listed as 8&11 in all the period reviews, but Porsche documentation from that period isn't great.
The only 8.5 listed in the PET for the 996 is 996 362 126 05 which appears to be a rear for winter use, so any further info would be appreciated.
Possibly Relevant Tidbit: I once went to a dealership and was talking to the service manager about wheel widths. We went out and measured a wheel on a car that had a rare option. He used a type of calipers that measured the outside width near the bead and he stated the size, which was 1/2" wider than it should have been. I cautioned him that the rim width is measured on the inside, so he needs to subtract 2 x rim thickness at the bead. He said, "That's not the way we were taught to measure wheels."
Last edited by edfishjr; Jan 15, 2022 at 11:48 AM.
Latest Ratings
Notes and changes:
1) for several cars which have auto trans with 2nd gears that top out in the low 50mph range, to calculate the thrust rating I have begun using a ratio midway between 2nd and 3rd and then subtracting 2% for the shifting. This is not good, but I don't know what to do better. Previously, I just used 3rd gear. I continue to use 3rd gear for the Supra because 2nd is even lower, i.e. less than 50mph and basically unusable. The main effect of this change is to move the Alpha Quad up considerably.
2) I've included the top AS car, the C6Z06, for reference, along with some other AS cars which may be of interest. Note that all BS cars lag considerably behind the C6Z06, but that many AS cars, including many Porsches and the C7Z51, are within the range of BS. The 997.1S manual moved up quite a bit when I used the XRR rim sizes. Even if the tires are the same, a better supported, less pinched tire works better.
3) I continue to use the 305/30-19 rear tire for the C6Z51. Now that I own one, it has become evident that it may not be feasible to go down to a shorter 18" rear tire, though legal. Unlike the C5, where you could run a larger front tire than the rear as long as the nannies were off, the C6 ABS appears to rebel strongly against running a front tire that is not smaller than the rear tire, at least at track speeds. (May be ok at autocross speeds... I don't know.) No suitable front tire, in either 17" or 18" diameter, is available that would not be a larger diameter than the rear tire.
4) 2022 Macan GTS added
Thanks for your work, Could you add a couple of SS cars that probably should be in AS? Thinking of 718 B/CGTS siblings, both 2.5 and 4.0 liter cars. BTW, if anyone is looking for the “unicorn” 981 CGTS, I pre-traded mine to Porsche Melbourne. PDK, PTV, and X73. I miss it and hope the replacement 718 CGTS 4.0 will be a worthy replacement.
Bob L
Last edited by Formulabob; Jan 16, 2022 at 12:39 PM.
Reason: Meant AS not BS
Thanks for your work, Could you add a couple of SS cars that probably should be in BS? Thinking of 718 B/CGTS siblings, both 2.5 and 4.0 liter cars. BTW, if anyone is looking for the unicorn 981 CGTS, I pre-traded mine to Porsche Melbourne. PDK, PTV, and X73. I miss it and hope the replacement 718 CGTS 4.0 will be a worthy replacement.
Bob L
Actually, I've already done it. Here is the version with the SS cars I've done shown.
One of the Caymans you mention is rated slightly faster than the M2C and one is slightly slower.
Added the 2021 Macan GTS, fixed some places where I wasn't consistent and color coded by class.
This system, by rating Thrust equal to Grip and Width, is very sensitive to Thrust calcs which are in turn very sensitive to gearing, tire sizes and any Thrust adjustments for turbo lag, etc. For some cars, the availability or non-availability of limited slip differentials may be important, but this is not a factor I take into account. (Effectively, this system assumes all cars can put down all available power at all times.) I think we went through a period (when 200TW was mandated in Street) when Thrust was less important. High torque motors couldn't get the power down very well. Since then tires have steadily gotten better, the result being that I think autocross speed now is again very dependent on how much Thrust can be delivered in the first one or two seconds after the apex. This also has increased course dependency within and between classes. At the same time manufacturers have given us small turbo motors with huge low-RPM torque and widely diverging lag characteristics which makes rating those cars against bigger normally aspirated motors problematic.
Last edited by edfishjr; Jan 16, 2022 at 11:51 AM.
Could you add the 997.2 GT3 to the list please? Yom plased well in his last year...... which will have no bearing on my potential performance in mine, LOL
Could you add the 997.2 GT3 to the list please? Yom plased well in his last year...... which will have no bearing on my potential performance in mine, LOL
I will. Please check my numbers:
Weight 3160 (no option, U.S. car, low gas)
62.5% rear weighted
Torque: 317 lb-ft
Rim widths: 8.5 and 12, assumed 18" wheels and 315/30-18 rear tire at 25.5" diameter.
WB = 92.7"
2nd gear ratio: 2.26
FD ratio: 3.44
I get the same numbers as you when I use teh google. It has been interesting to think about this car in terms of thrust, and why it performs like an AS car on small courses, and more like a SS car on large courses. I've attached the dyno sheet from my personal car, and you can see the torque curve is basically a step function at 5,000 RPM (sorry the dyno operator printed this in a ridiculous scale). I would say at most autocross events this thing is stuck in the ~280ft lbs zone rather than 317ft lbs. I'm actually kind of surprised these are as good at autocross as they are. And yes I know you're referencing flywheel HP and torque numbers, whuch is not what I'm showing.
Why is GT4 slower than 981CS in your calculations? On a related note, I still think you're weighting 987.2 PDK too severely; they're just not a significant advantage for a 1-shift autocross due to the higher weight everywhere else. You're not treating 981 so harshly.
I get the same numbers as you when I use teh google. It has been interesting to think about this car in terms of thrust, and why it performs like an AS car on small courses, and more like a SS car on large courses. I've attached the dyno sheet from my personal car, and you can see the torque curve is basically a step function at 5,000 RPM (sorry the dyno operator printed this in a ridiculous scale). I would say at most autocross events this thing is stuck in the ~280ft lbs zone rather than 317ft lbs. I'm actually kind of surprised these are as good at autocross as they are. And yes I know you're referencing flywheel HP and torque numbers, whuch is not what I'm showing.
What I actually use in order to calculate thrust is 88% of the flywheel torque from the manufacturer. This allows me, when I have to, like with the M2 and the Supra, to directly input dyno numbers when the manufacturer is clearly playing games.
Your point is very valid in that such cars as yours do not perform as well as a high displacement or turbo motors which have more area under the curve at autocross "coming off the corner" speeds.
Why is GT4 slower than 981CS in your calculations? On a related note, I still think you're weighting 987.2 PDK too severely; they're just not a significant advantage for a 1-shift autocross due to the higher weight everywhere else. You're not treating 981 so harshly.
I'll check the numbers. Won't be the first time I've made a mistake or have some bad data.
Why is GT4 slower than 981CS in your calculations? On a related note, I still think you're weighting 987.2 PDK too severely; they're just not a significant advantage for a 1-shift autocross due to the higher weight everywhere else. You're not treating 981 so harshly.
I had a mistake.
While working with only the AS & BS cars I made a change to how I calculate the total rating. That change didn't get applied to the SS cars that were on hidden rows. So, here is a fixed version that shows all of the SS, AS and BS cars I've rated, including the asked-for 991 GT3.
The 981CS still rates very slightly above the GT4 and maybe I need some help here. I have the 981CS ratio at 2.05 and the GT4 at 1.95 as a difference. However, that's not the only one. I have the GT4 needing to use a 26.3" (19" rim) tire, i.e. the 305/30-19 Falken. I have the 981CS using a 25.1" tire, which would be the Yoko A052 295/30-18. Do you think these are the best tires each could use? Can the GT4 use an 18" rim to help fix its unfortunate gear ratio?
I've drawn a red box around all the cars grouped in the 90 to 91 point range. These cars rate very closely. There's just not much between them until you want to start throwing in intangibles.
What I do want to point out, however, are the 3 AS cars inside that box and below the M2C and the 2 other AS cars that are below that box. I think if those 5 cars had been pushed down to BS this year along with the 996 and C6Z51 then BS would have been a reasonably healthy class this year and bonkers huge by
next year.
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