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People were of the opinion that the transient response was receiving too much weight. This cuts it down which has some effect.
Please note that just looking at the list can give you a wrong impression. If you look at the numbers you will see that the difference between the 987.1CS and the M2 is not very much, for instance.
I've always had a suspicion that the 987.2 Cayman with PDK, Sportchrono, etc., if you could find one, would be faster in BS than the 987.1 Cayman. This latest set of ratings, which is for the slightly lighter manual 987.2, indicates they are very close. (I don't know how to rate the PDK, but I think it might be faster if you really learned how to use it. I know that people who have tried it have their doubts due to the inability of getting quick shifts when you need them.)
I'm a bit surprised (and happy) they put the 718 Cayman/Boxster T in AS. PDK, Sport Chrono, PTV, and PASM Sport (10mm lower and stiffer suspension w/stiffer sways), with carbon buckets as an available option. This could be a contender.
I'm a bit surprised (and happy) they put the 718 Cayman/Boxster T in AS. PDK, Sport Chrono, PTV, and PASM Sport (10mm lower and stiffer suspension w/stiffer sways), with carbon buckets as an available option. This could be a contender.
Yeah we didn't think the 10mm lower vs a regular Cayman +PDK+PTV+SC that you can already run in AS was significant enough split it out. We also thought the 981 S / GTS with all the goodies was slightly superior to the T for AX.
@edfishjr This is awesome work. I did something similar when I was deciding which car to get for AS about a year and a half ago. For various reasons, I was only looking at new cars, and ended up ordering a 718 Cayman (base) over the M2 and the Camaro 1LE (which was in AS at the time). I looked at wheel width, track width, wheelbase, weight, torque and horsepower. My calculations were pretty rudimentary, but I did come up with the 718 as the winner.
I couldn't find the formulas you used to arrive at the various ratings by searching the forums. Are they proprietary?
I'd be curious if there's a way to include the Tesla Model 3, given the differences between EV and ICE propulsion.
@edfishjr This is awesome work. I did something similar when I was deciding which car to get for AS about a year and a half ago. For various reasons, I was only looking at new cars, and ended up ordering a 718 Cayman (base) over the M2 and the Camaro 1LE (which was in AS at the time). I looked at wheel width, track width, wheelbase, weight, torque and horsepower. My calculations were pretty rudimentary, but I did come up with the 718 as the winner.
I couldn't find the formulas you used to arrive at the various ratings by searching the forums. Are they proprietary?
I'd be curious if there's a way to include the Tesla Model 3, given the differences between EV and ICE propulsion.
I haven't published the actual formulas in the spreadsheet. I have shared the spreadsheet with certain SCCA activity committee folks that do something similar for classing purposes. They were interested in comparing their methods to mine.
I've not tried to rank the Tesla or other cars that are very different from the norm. The method is too simple to account for differences between 2WD and 4WD, electric vs. IC, etc. For instance, even though this is the only attempt that I know of to quantify transient response and use it to predict autocross speed, the mass distribution of the Tesla is so different that the method will significantly under-predict it's transient response. (The method will "work" for front engine, mid-engine or rear engine, but will not work for a car with the low-CG caused by batteries in the floor.)
The largely unrecognized massively good effect that the Tesla's weight distribution has on transient response is probably one of the reasons people underestimated it.
Last edited by edfishjr; Feb 11, 2020 at 10:11 AM.
Also, coming from the 2015+ Mustang platform, I can assure you that it's not even close to the E9x M3 in reality, nor the latest 1LE Camaro. 1LE and GT350 should be adjusted to be higher up the BS order as they've shown to be just as or more competitive than 987.1 S cars.
Also, coming from the 2015+ Mustang platform, I can assure you that it's not even close to the E9x M3 in reality, nor the latest 1LE Camaro. 1LE and GT350 should be adjusted to be higher up the BS order as they've shown to be just as or more competitive than 987.1 S cars.
No 997/991 cars mostly because 1) they are non-factors in SCCA autocross, and 2) not cars I was interested in at the time.
I've continued to work on this. I put the Elise into the AS list and used it vs. the C6Z06 as a guide to adjusting the weighting of the various factors, knowing how close those two cars were to each other at Nats for many years on R-comps, with large course dependency. (That actually helps understand how to weight the factors.) Previously, the change to street tires meant that this wouldn't work. But, now that the street tires are so much better at putting power down I think the comparison is valid again. This produced some large changes. I can tell you that the GT350 is presently just behind the Supra in BS with the M2s on top and the Caymans underneath. Even so, I recognize that the Supra has advantages that are not reflected in the numbers. I watched Marcus in his BS Supra go through the 180 turnaround at Dixie Winter in December. I thought it was the fastest car around that long sweeper of any car on street tires and faster than 60% of the R-comp cars. The level of grip was amazing. And that's in addition to its tremendous agility. Of course, driver ability is hard to factor out. And lots of R-comp-tired, more modified cars are too stiff in springs and shocks for best steady-state grip, especially on asphalt, IMHO.
As for the M3, that's just how it comes out on paper. I have no doubt that it's faster than the numbers indicate. But I don't move cars around based on actual performance. (Anyone can do that.) I do sometimes play around with other factor adjustments, such as adding or subtracting a point for various advantages or disadvantages. For instance, I add 1 point to the C5 in BS for low-CG. I subtract 1 point from the GT350 for high CG. (Otherwise it would be above the Supra) I add 5% to the thrust rating to all mid and rear engined cars. I subtract 5% from the Mustang thrust rating for a peaky engine. But, those things are somewhat subjective, though based on real differences, and are mostly just for my own thinking.
Last edited by edfishjr; Jan 20, 2021 at 10:24 AM.
No 997/991 cars mostly because 1) they are non-factors in SCCA autocross, and 2) not cars I was interested in at the time.
I've continued to work on this. I put the Elise into the AS list and used it vs. the C6Z06 as a guide to adjusting the weighting of the various factors, knowing how close those two cars were to each other at Nats for many years on R-comps, with large course dependency. (That actually helps understand how to weight the factors.) Previously, the change to street tires meant that this wouldn't work. But, now that the street tires are so much better at putting power down I think the comparison is valid again. This produced some large changes. I can tell you that the GT350 is presently just behind the Supra in BS with the M2s on top and the Caymans underneath. Even so, I recognize that the Supra has advantages that are not reflected in the numbers. I watched Marcus in his BS Supra go through the 180 turnaround at Dixie Winter in December. I thought it was the fastest car around that long sweeper of any car on street tires and faster than 60% of the R-comp cars. The level of grip was amazing. And that's in addition to its tremendous agility. Of course, driver ability is hard to factor out. And lots of R-comp-tired, more modified cars are too stiff in springs and shocks for best steady-state grip, especially on asphalt, IMHO.
As for the M3, that's just how it comes out on paper. I have no doubt that it's faster than the numbers indicate. But I don't move cars around based on actual performance. (Anyone can do that.) I do sometimes play around with other factor adjustments, such as adding or subtracting a point for various advantages or disadvantages. For instance, I add 1 point to the C5 in BS for low-CG. I subtract 1 point from the GT350 for high CG. (Otherwise it would be above the Supra) I add 5% to the thrust rating to all mid and rear engined cars. I subtract 5% from the Mustang thrust rating for a peaky engine. But, those things are somewhat subjective, though based on real differences, and are mostly just for my own thinking.
That makes sense. Thanks for confirming that the 997 C2/C2S are not even on the table as far as competitiveness. This is what I've gathered from all the results data. If they were, people would be using them. What's curious to me is why they are still in AS if they're that uncompetitive...
That makes sense. Thanks for confirming that the 997 C2/C2S are not even on the table as far as competitiveness. This is what I've gathered from all the results data. If they were, people would be using them. What's curious to me is why they are still in AS if they're that uncompetitive...
Actually, I don't have an opinion on the competitiveness of the 997s, much less the later cars. Actually, it wouldn't surprise me if the 997C2S is not very far off kind of like the standard C6Z51 is not really very far off the C6Z06. I just meant that no one fast has seriously run a well-prepped one that I know of.
OK, you've got me interested. I'll do the numbers and report back!
Actually, I don't have an opinion on the competitiveness of the 997s, much less the later cars. Actually, it wouldn't surprise me if the 997C2S is not very far off kind of like the standard C6Z51 is not really very far off the C6Z06. I just meant that no one fast has seriously run a well-prepped one that I know of.
OK, you've got me interested. I'll do the numbers and report back!
I mean I see C6 Z51s being in the mix regularly, even at nationals. That said, there are zero C2S in the SS or AS competitors for all of the last three years. Has to mean something!
That said, there are zero C2S in the SS or AS competitors for all of the last three years. Has to mean something!
Sounds like the kind of challenge I'd be interested in - if I had the money.
We moved the (non-turbo, not GT) 997 to AS this year. Top-of-the-pops from the line would be a 997.2 GTS w/ PDK, theoretically. Not sure it would do anything better than a 718T or a 981S, let alone a C6Z.
I rated the 997.2 Carrera S manual trans. The PDK might well be faster, but the manual car is not geared too badly in 2nd. I assumed a 315/30-18 rear tire.
As I said, the list is quite changed from previous postings after I added the Elise and adjusted things to 1) make the Elise have a similar but slightly lower overall rating compared to the C6Z06, and 2) adjust the various weightings so that on a super tight & twisty course it would beat the C6Z06 and on a power/sweeper course it would lose to the C6Z06. Note the insane Elise transient response rating!
Last edited by edfishjr; Jan 20, 2021 at 08:30 PM.
Reason: reduced 04 Boxster S to 7.5/9 wheel widths
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