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It's a start but there is a LOT missing from there.
You cell is simply using peak torque. More useful would be a thrust chart. Here's one PedalFaster made comparing a C5 vs. S2k vs. 986S:
Here you can see the peak torque plus short gearing of the s2k puts it at similar thrust to the other two cars from 45-59mph, but it gets caught flat footed under 43mph or so.
Corvette has a huge torque advantage. How much of that can be put down in a straight line? How about while turning? The C5 can theoretically rip it's way though most of many courses in 1st gear. It has an almost unbelievable thrust advantage in 1st from 40-55mph. But in reality, street tires cannot put down 0.7 longitudinal G even in a straight line, let alone when asked to turn simultaneously. So many C5 drivers use 2nd. The 911 with it's rear bias can real-world put down much more power while turning, which is difficult to model into a spreadsheet.
The C5 is about 74" wide. The 996 is about 69" wide. All other things equal, which can get through a slalom quicker?
Corvette has a 104" wheelbase. 996 has a 92" wheelbase. Which is better in what situations, and how do you quantify for that?
A great example is this: through simple calculations a skinny wheeled, low power 996 GT3 should be no match for a 505hp C6 Z06 let alone a torque and tire monster Viper in SSR. But G.J. Dixon has gone back to back on the largest stage in the sport, against some of the best drivers, and not even in what people think is the best GT3.
The SCCA knows it's not just thrust and tire and weight, and gets a much clearer picture of the ultimate possible performance of a chassis through results like that. I'm not saying to give up on writing your STU 996 letters, as I still think it would be a pretty good fit and a ton of fun to build one. I'm just saying SCCA isn't necessarily being hard headed if they deny the request.
It's a start but there is a LOT missing from there.
You cell is simply using peak torque. More useful would be a thrust chart. Here's one PedalFaster made comparing a C5 vs. S2k vs. 986S:
Here you can see the peak torque plus short gearing of the s2k puts it at similar thrust to the other two cars from 45-59mph, but it gets caught flat footed under 43mph or so.
Corvette has a huge torque advantage. How much of that can be put down in a straight line? How about while turning? The C5 can theoretically rip it's way though most of many courses in 1st gear. It has an almost unbelievable thrust advantage in 1st from 40-55mph. But in reality, street tires cannot put down 0.7 longitudinal G even in a straight line, let alone when asked to turn simultaneously. So many C5 drivers use 2nd. The 911 with it's rear bias can real-world put down much more power while turning, which is difficult to model into a spreadsheet.
The C5 is about 74" wide. The 996 is about 69" wide. All other things equal, which can get through a slalom quicker?
Corvette has a 104" wheelbase. 996 has a 92" wheelbase. Which is better in what situations, and how do you quantify for that?
A great example is this: through simple calculations a skinny wheeled, low power 996 GT3 should be no match for a 505hp C6 Z06 let alone a torque and tire monster Viper in SSR. But G.J. Dixon has gone back to back on the largest stage in the sport, against some of the best drivers, and not even in what people think is the best GT3.
The SCCA knows it's not just thrust and tire and weight, and gets a much clearer picture of the ultimate possible performance of a chassis through results like that. I'm not saying to give up on writing your STU 996 letters, as I still think it would be a pretty good fit and a ton of fun to build one. I'm just saying SCCA isn't necessarily being hard headed if they deny the request.
All good points. One correction: C5 doesn't get anywhere near 55 in first. Something screwey.
For a C5Z06 bump the green 2nd gear curve up by 27%. That's about the difference made by torque and gearing and why it's such a good auto-x machine.
which is why it's ludicrous to place a 996 in the same class as a C5z06 unless you're going to allow the 996 to run the exclusive options to at least give it a fighting chance.
which is why it's ludicrous to place a 996 in the same class as a C5z06 unless you're going to allow the 996 to run the exclusive options to at least give it a fighting chance.
I agree that std. 996 should be in BS. On the other hand, I just read about exclusive options: "anything technically feasible ...right from the factory ." Arguing for that is a good way to get all Porsches declassed from SCCA competition for ever.
I agree that std. 996 should be in BS. On the other hand, I just read about exclusive options: "anything technically feasible ...right from the factory ." Arguing for that is a good way to get all Porsches declassed from SCCA competition for ever.
Fortunately for us, "whatever you can dream up" is not a "standard option". Some of the out-of-the-catalog Porsche Exclusives could be considered standard options, though.
I would argue that if it's an option on the standard option code list and it's installed at the factory that it should be considered street/stock legal . . . . . . but I won't start that argument unless our STU proposal gets ****canned.
I would argue that if it's an option on the standard option code list and it's installed at the factory that it should be considered street/stock legal . . . . . . but I won't start that argument unless our STU proposal gets ****canned.
These are two different ideas, though, and not directly related. One applies to Street, the other to ST. Or do you just mean that your level of caring is variable?
As for the STU letters, I wouldn't take the recent letters as resulting in a binary event. While you might get a response along the lines of "not at at this time, class fit, current performance, blah blah blah" the truth is that letters over time have an additive effect. When we think about what changes need to happen in the future, we tend to look at what we think would be well received and what has been requested.
All that being said, just wait and see what's in the next Fastrack or two.
Factors to consider:
1. The STAC is majority new members for the first time in years.
2. There have been lots of letters over the past year or two for cars that don't seem to fit current structure.
3. Big boats take time to change course, especially given the fact that not many changes in established classes are seen as win-win for all involved.
What makes you think that? Have you done the math or are you just guessing?
1. I own one and run data
2. I like the turnzero.com calculator. for a 6000 rpm redline, Hankook 285/35-18 tires and accounting for tire deformation it gives 49.2 mph
3. I calculate it as 6000 rpm/3.42/2.66 *pi*25.9" /12inperfoot/60secondsperminute *.97 (deformation factor) gives 72.3 ft/s. I seem to recall that 60 mph is right at 88 ft/s, so 72.3 gives 49.3 mph.
Well there seems to be the on paper answer for top speed C5 banging the rev limiter in 2nd gear, (86 MPH) on 99% of the AX courses around the nation this is not possible.
however 49 MPH is mostly reflecting a short postage stamp course
We have data from Blythville NT's showing high 60's to low 70's (on Hoosiers).
Given the lack of choices at present, I just ordered some 285/30-18 Dunlop Z2SS from Tirerack for rears to start the year off. At 6200 rpm cutoff that should be 48.5 in 1st and 72.6 in 2nd. That's a 5.2% gear ratio change compared to the 295/35-18 I ran last year.
02-04-2015, 12:31 PM
