Orthojoe's GT4 track thread and ramblings
#1051
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I agree with everything you are saying and run NASA TT in an E36 M3 where 2 seconds is an eternity.
Track conditions were actually worse on the 2 min lap because HPR ground down the hairpin at turn 8 for work. You can see it is a mess in the vid.
Just sharing my personal experience.
Track conditions were actually worse on the 2 min lap because HPR ground down the hairpin at turn 8 for work. You can see it is a mess in the vid.
Just sharing my personal experience.
#1052
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So in essence 5 1/2 month between tests. Mile high race track weather would affect performance of the vehicle as well. I think there are several of you that go out there for open track days as well. That brings up the question with all those additional runs between those dates have you become more comfortable in the car and could that be a contributing factor?
#1053
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is here a ride height difference between this and stock? I don't want to drop ride height and want to see if this will affect rake.
#1054
#1055
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Originally Posted by Eric5280
Hey Joe.
I hear ya, but I did 2:01.7 PB (.5 faster than no DSC) with DSC on Dunlops.
Swapped on RE71R's and could not break 2:03 for the life of me. Installed TPC rear links and front springs; 2 min dead in my very session out. Alignment was out a little which is why I credit the mods with approx 2 sec on RE71's.
Just my personal experience on RE71. Car much more stable, higher entry/exit speeds of turns. Very happy.
I hear ya, but I did 2:01.7 PB (.5 faster than no DSC) with DSC on Dunlops.
Swapped on RE71R's and could not break 2:03 for the life of me. Installed TPC rear links and front springs; 2 min dead in my very session out. Alignment was out a little which is why I credit the mods with approx 2 sec on RE71's.
Just my personal experience on RE71. Car much more stable, higher entry/exit speeds of turns. Very happy.
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#1056
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Lap time improvements due to modifications are difficult to quantify. I have a feeling springs or the DSC module make little difference on the absolute best possible lap time. However, I would guess that they help with predictability and consistency.
Personally, I'm interested in whether wider front wheels and tires lower lap times. I'd guess that this modification would enable later braking and more trail braking, increasing the speeds in the first half of the corner, if it helps at all. Here's video of an S2000 that had a min speed of 75 mph in turn 2 at thunderhill, which is comparable to GT4 min speeds in that corner, however, in turn 1 the S2000 is going 100 mph at the third brake marker and only slows to 89 just before the apex of the turn. I haven't seen GT4s entering 1 that quick, but that may just be because the S2000 driver is superhuman. Still I wonder if there's something to be gained with front grip.
On another note, I think dive planes and a gurney flap would net 0.5 mph in turn 8. A different S2000 than the car mentioned above rolled through 8 with a min speed of 105.5 mph(!) with about 2-2.5x the downforce of the GT4. By my calculations the downforce on this S2000 (again not the one above) is worth about 3-3.5 mph over the GT4, so the GT4 should be able to do 102 mph or 102.5 with dive planes and a gurney flap through 8.
Personally, I'm interested in whether wider front wheels and tires lower lap times. I'd guess that this modification would enable later braking and more trail braking, increasing the speeds in the first half of the corner, if it helps at all. Here's video of an S2000 that had a min speed of 75 mph in turn 2 at thunderhill, which is comparable to GT4 min speeds in that corner, however, in turn 1 the S2000 is going 100 mph at the third brake marker and only slows to 89 just before the apex of the turn. I haven't seen GT4s entering 1 that quick, but that may just be because the S2000 driver is superhuman. Still I wonder if there's something to be gained with front grip.
On another note, I think dive planes and a gurney flap would net 0.5 mph in turn 8. A different S2000 than the car mentioned above rolled through 8 with a min speed of 105.5 mph(!) with about 2-2.5x the downforce of the GT4. By my calculations the downforce on this S2000 (again not the one above) is worth about 3-3.5 mph over the GT4, so the GT4 should be able to do 102 mph or 102.5 with dive planes and a gurney flap through 8.
Last edited by Yargk; 02-21-2017 at 08:49 PM.
#1057
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FWIW, I'm not convinced that 265 up front does anything and might actually be slower. Here is why:
1) Potter's first day at thill he ran 1:58 on oem tires. After he switched to 265, he was no faster.
2) Potter's best time at Sonoma is 1:48.2 on 265, which matches my best time there of 1:48.2 on 245s. Potter is a better driver than me.
3) A pro driver (hartanto) bought a GT4 with 265s and is planning on downsizing because he thinks the tires are too wide for 9" wheels and didn't like the way they performed.
1) Potter's first day at thill he ran 1:58 on oem tires. After he switched to 265, he was no faster.
2) Potter's best time at Sonoma is 1:48.2 on 265, which matches my best time there of 1:48.2 on 245s. Potter is a better driver than me.
3) A pro driver (hartanto) bought a GT4 with 265s and is planning on downsizing because he thinks the tires are too wide for 9" wheels and didn't like the way they performed.
#1058
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So we can say that 265s "might be" slower, but
we really don't know. It's more of a feeling.
It'd be nice to test, same driver, same day.
we really don't know. It's more of a feeling.
It'd be nice to test, same driver, same day.
#1059
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FWIW, I'm not convinced that 265 up front does anything and might actually be slower. Here is why:
1) Potter's first day at thill he ran 1:58 on oem tires. After he switched to 265, he was no faster.
2) Potter's best time at Sonoma is 1:48.2 on 265, which matches my best time there of 1:48.2 on 245s. Potter is a better driver than me.
3) A pro driver (hartanto) bought a GT4 with 265s and is planning on downsizing because he thinks the tires are too wide for 9" wheels and didn't like the way they performed.
1) Potter's first day at thill he ran 1:58 on oem tires. After he switched to 265, he was no faster.
2) Potter's best time at Sonoma is 1:48.2 on 265, which matches my best time there of 1:48.2 on 245s. Potter is a better driver than me.
3) A pro driver (hartanto) bought a GT4 with 265s and is planning on downsizing because he thinks the tires are too wide for 9" wheels and didn't like the way they performed.
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245 is a tad wide for 8.5s too actually. Probably wouldn't change much against the stopwatch, but stock tires with 9X20 in the front might feel a bit better...
#1061
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Originally Posted by RDCR
Joe, for some reason I thought you went with the 265s because they were lasting longer? (or you thought they would).
#1062
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Originally Posted by Yargk
Thanks for the data points, I was aware of 1 and 2, but 3 is new to me. Makes sense though, 265 is a bit wide for 9s. 9s were fitted by many people without camber plates (that actually bring the tire in.) I always thought that 9.5s could fit with the perfect offset, trimming of the brake duct, and camber plates, and perhaps 265s on 9.5s would be optimal, but this is just a guess and doesn't follow from point 1 and 2 above. (heck maybe they won't fit and if they do 9.5s wouldn't be faster either
)
245 is a tad wide for 8.5s too actually. Probably wouldn't change much against the stopwatch, but stock tires with 9X20 in the front might feel a bit better...
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245 is a tad wide for 8.5s too actually. Probably wouldn't change much against the stopwatch, but stock tires with 9X20 in the front might feel a bit better...
991RS runs 265 with 9.5", fwiw
#1063
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#1065
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Originally Posted by Shockwave
Andrie bought a GT4! Thats amazing. He is well known in the S2000 community. Very fast!