scca stock class becoming street class!
05-04-2015, 02:04 AM
#527
C5 doesn't get anywhere near 55 in first. Something screwey.
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.
Approximately.
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.
Approximately.
I wonder if the difference is in the engine revisions that happened in 2001.
05-05-2015, 01:59 PM
#528
Burning Brakes
I'm probably the only person who remembers / cares about this exchange, but since it happened I bought and tested a 2002 Corvette, and I can do 83 - 84 GPS-verified km/h in first on slightly worn 275 Bridgestones, which converts to about 52 mph.
I wonder if the difference is in the engine revisions that happened in 2001.
I wonder if the difference is in the engine revisions that happened in 2001.
Earlier I used 6000 rpm redline and a deformation factor.
05-15-2015, 01:06 PM
#529
Drifting
For those who haven't seen it yet, check out the autocross tire test in this month's Grassroots Motorsports issue. David Whitener and Andy Hollis tested RE-71R & Rival S vs Rival, ZII* and AD-08R. R-S3v2 and V720 were unfortunately not available for the test.
So... I just ordered a set of Bridgestone RE-71R. Anyone running these yet who can talk about pressures to start at for AS/SS Porsches? I was planning on starting near the upper range of where I ran ZII* and go from there. I'm worried about rollover on my front tires as I'm running 255/35-18 on 8x18" wheels.
So... I just ordered a set of Bridgestone RE-71R. Anyone running these yet who can talk about pressures to start at for AS/SS Porsches? I was planning on starting near the upper range of where I ran ZII* and go from there. I'm worried about rollover on my front tires as I'm running 255/35-18 on 8x18" wheels.
05-15-2015, 01:54 PM
#530
05-15-2015, 04:05 PM
#531
Anyone else not the GRM test ran a 205 on an 8" wheel?
Word on the street is the new street tires like to be run at the width of the wheel - 205 on an 8; 255 on a 10.
The Rival S apparently does ok overtiring.
Word on the street is the new street tires like to be run at the width of the wheel - 205 on an 8; 255 on a 10.
The Rival S apparently does ok overtiring.
05-15-2015, 04:11 PM
#532
Drifting
This is one of the many complaints I have of GRM testing: it's not entirely applicable to Street classes. TireRack's testing at door panel pressures and OEM alignment isn't very good either. I really wish GRM would follow up ST* testing with some form of Street testing.
There's another test coming up where the test one specific tire on 3 different wheels to see how it handles overtiring. That doesn't interest me. Why can't they test 3 different size tires on 1 camber-challenged wheel to see how much tire is too much? Conventional wisdom is that overtiring a wheel trades transient response for response in sweepers.
There's another test coming up where the test one specific tire on 3 different wheels to see how it handles overtiring. That doesn't interest me. Why can't they test 3 different size tires on 1 camber-challenged wheel to see how much tire is too much? Conventional wisdom is that overtiring a wheel trades transient response for response in sweepers.
05-22-2015, 12:22 AM
#533
Interestingly, James Yom (2013 B Stock national champion, second in F Street in 2014) is contesting tomorrow's Lincoln Pro in a 996. Not sure how prepped it is, though -- it looked roly-poly on the test course and was very quiet, and in my very brief discussion with him he didn't seem super happy with the car. Still, he has a demonstrated history of getting the best (scratch times, anyway 
) out of new-to-him cars, so it'll be interesting to see how he does.
) out of new-to-him cars, so it'll be interesting to see how he does.
05-22-2015, 11:10 AM
#534
I know I posted in the other thread - but now that I'm running Koni Yellows, a proper alignment and a custom exhaust (weighs 20 lbs vs. 50 for the old one, although it's rather loud) I'm actually rather enjoying the car. We'll see how it does once it gets real tires.
05-22-2015, 01:06 PM
#536
Interestingly, James Yom (2013 B Stock national champion, second in F Street in 2014) is contesting tomorrow's Lincoln Pro in a 996. Not sure how prepped it is, though -- it looked roly-poly on the test course and was very quiet, and in my very brief discussion with him he didn't seem super happy with the car. Still, he has a demonstrated history of getting the best (scratch times, anyway ) out of new-to-him cars, so it'll be interesting to see how he does.
) out of new-to-him cars, so it'll be interesting to see how he does.Also not so bad yourself, Stephen...
05-22-2015, 04:11 PM
#537
The car James is driving has M030 and Konis; I forgot to ask him if it has a bar. The two guys he's beating, Jed and Vivek, are both very solid drivers, but they're both going slower than I'd expect, so I wouldn't read too much into the standings quite yet.
Now if only it would stop sprinkling...
Now if only it would stop sprinkling...
05-25-2015, 11:58 AM
#539
wow. ok. I guess the 996 with a good driver isn't such a bad choice after all?
Locally I had 3rd/89 FTD and 6th/89 PAX on Hankooks . . . lets see what happens with the RE71rs I just bought.
18x8/18x10 wheels, yellow shocks, GT3 seats (I'm not taking these out) and custom light exhaust. Finally got the Konis, pressures, and alignment dialed in.
Locally I had 3rd/89 FTD and 6th/89 PAX on Hankooks . . . lets see what happens with the RE71rs I just bought.
18x8/18x10 wheels, yellow shocks, GT3 seats (I'm not taking these out) and custom light exhaust. Finally got the Konis, pressures, and alignment dialed in.
05-26-2015, 04:14 PM
#540
As a counterpoint to that, James got crushed pretty badly at the Tour, although there were extenuating circumstances. From James:
The body roll makes the Porsche too difficult to drive at 10/10ths. At 9/10ths its manageable, but at 10/10ths it can't keep up with fast sections where you have to wiggle the car. The launch and my consistent .5 reaction times helped me win the pro. Also, Vivek switched to the Bridgestone [for the Tour, which he won by 1.2 seconds over another Z06] which he clearly likes better
Apparently I made a strategic error. The lack of camber is really killing the outer shoulder of the front tires, so I flipped them Sunday morning. Bad call. That weird wear ppl get in the middle "lifted" the inner third of the tire reducing contact patch. The car had less front grip on day 1 of tour. After the 3 runs, the tire wore itself straighter and the car seemed more normal on day 2. Still .6-.9 behind a Z06, but on par with the CR and I'm sure the boxter/cayman s. But now with the stupid Z06 in the class, all the other cars are junk.
Apparently I made a strategic error. The lack of camber is really killing the outer shoulder of the front tires, so I flipped them Sunday morning. Bad call. That weird wear ppl get in the middle "lifted" the inner third of the tire reducing contact patch. The car had less front grip on day 1 of tour. After the 3 runs, the tire wore itself straighter and the car seemed more normal on day 2. Still .6-.9 behind a Z06, but on par with the CR and I'm sure the boxter/cayman s. But now with the stupid Z06 in the class, all the other cars are junk.