SC max speed
05-12-18, 09:05 AM
#16
Harold you should go to the Texas mile in Victoria( used to be in beeville). It's an awesome time , if you participate or are just a spectator. I had only been to it when it was in beeville.
05-12-18, 11:15 AM
#17
Lead Lap
Sounds interesting but a bit far unless I'm down in the Houston area.
05-14-18, 02:54 AM
#19
I've hit the governor limit of 155MPH once when a Corvette kept taunting me on the freeway. We were both doing about 95 and he was attempting to overtake me again, when I just let it open and left him behind trying to catch up.
Drove at 155 for about 5 minutes before the tires overheated and I lost about 10lbs of pressure in the front passenger tire and had to pull off an exit to let them cool down and refill. The corvette was not able to catch up to me during that 5 minutes. More likely due to the driver's mettle than the corvettes capabilities - he should have been able to smoke me since my SC is still stock.
I've noticed that right around 90-110, the SC feels likes it is in the 'zone' and handling feels very smooth and road grip seems to be at max. Above 120 it felt like it was lifting a bit.
I was on a long trip, and the engine was already heated up, so it had a lot of power. We were the only two cars, except for a semi we had just passed, for as far as I could see or else I would have never attempted it. Not something I would do again.
155 is really not that impressive, honestly. I had my 1988 6-cyl Toyota Corolla up to 140mph way back when (upstate NY on the thruway). Of course, it was shaking like crazy and felt far more unstable than the SC430. Just about any decent car should be able to reach those speeds.
The acceleration power is the real measurement, IMHO. At least on my SC430, this seems so inconsistent. Sometimes, I can get up to 50mph from a light change before hitting the other side of the intersection and other times, it feels like it is working its butt off just trying to get up to 45. I never participate when people try to challenge because of that. I never know what I am going to get. It's a bit embarrassing when trying to pass on the highway and it decides it wants to be a sloth. Yet, other times, I press the pedal and off it goes. Very inconsistent. And very frustrating.
I've read somewhere that the top speed of the stock SC430 is 210MPH (not sure if that applies to the -2005 model years). That would be impressive (if the car -and tires- could actually handle it)
Drove at 155 for about 5 minutes before the tires overheated and I lost about 10lbs of pressure in the front passenger tire and had to pull off an exit to let them cool down and refill. The corvette was not able to catch up to me during that 5 minutes. More likely due to the driver's mettle than the corvettes capabilities - he should have been able to smoke me since my SC is still stock.
I've noticed that right around 90-110, the SC feels likes it is in the 'zone' and handling feels very smooth and road grip seems to be at max. Above 120 it felt like it was lifting a bit.
I was on a long trip, and the engine was already heated up, so it had a lot of power. We were the only two cars, except for a semi we had just passed, for as far as I could see or else I would have never attempted it. Not something I would do again.
155 is really not that impressive, honestly. I had my 1988 6-cyl Toyota Corolla up to 140mph way back when (upstate NY on the thruway). Of course, it was shaking like crazy and felt far more unstable than the SC430. Just about any decent car should be able to reach those speeds.
The acceleration power is the real measurement, IMHO. At least on my SC430, this seems so inconsistent. Sometimes, I can get up to 50mph from a light change before hitting the other side of the intersection and other times, it feels like it is working its butt off just trying to get up to 45. I never participate when people try to challenge because of that. I never know what I am going to get. It's a bit embarrassing when trying to pass on the highway and it decides it wants to be a sloth. Yet, other times, I press the pedal and off it goes. Very inconsistent. And very frustrating.
I've read somewhere that the top speed of the stock SC430 is 210MPH (not sure if that applies to the -2005 model years). That would be impressive (if the car -and tires- could actually handle it)
Last edited by Retroplay; 05-14-18 at 02:59 AM.
05-14-18, 05:28 AM
#20
I've hit the governor limit of 155MPH once when a Corvette kept taunting me on the freeway. We were both doing about 95 and he was attempting to overtake me again, when I just let it open and left him behind trying to catch up.
Drove at 155 for about 5 minutes before the tires overheated and I lost about 10lbs of pressure in the front passenger tire and had to pull off an exit to let them cool down and refill. The corvette was not able to catch up to me during that 5 minutes. More likely due to the driver's mettle than the corvettes capabilities - he should have been able to smoke me since my SC is still stock.
I've noticed that right around 90-110, the SC feels likes it is in the 'zone' and handling feels very smooth and road grip seems to be at max. Above 120 it felt like it was lifting a bit.
I was on a long trip, and the engine was already heated up, so it had a lot of power. We were the only two cars, except for a semi we had just passed, for as far as I could see or else I would have never attempted it. Not something I would do again.
155 is really not that impressive, honestly. I had my 1988 6-cyl Toyota Corolla up to 140mph way back when (upstate NY on the thruway). Of course, it was shaking like crazy and felt far more unstable than the SC430. Just about any decent car should be able to reach those speeds.
The acceleration power is the real measurement, IMHO. At least on my SC430, this seems so inconsistent. Sometimes, I can get up to 50mph from a light change before hitting the other side of the intersection and other times, it feels like it is working its butt off just trying to get up to 45. I never participate when people try to challenge because of that. I never know what I am going to get. It's a bit embarrassing when trying to pass on the highway and it decides it wants to be a sloth. Yet, other times, I press the pedal and off it goes. Very inconsistent. And very frustrating.
I've read somewhere that the top speed of the stock SC430 is 210MPH (not sure if that applies to the -2005 model years). That would be impressive (if the car -and tires- could actually handle it)
Drove at 155 for about 5 minutes before the tires overheated and I lost about 10lbs of pressure in the front passenger tire and had to pull off an exit to let them cool down and refill. The corvette was not able to catch up to me during that 5 minutes. More likely due to the driver's mettle than the corvettes capabilities - he should have been able to smoke me since my SC is still stock.
I've noticed that right around 90-110, the SC feels likes it is in the 'zone' and handling feels very smooth and road grip seems to be at max. Above 120 it felt like it was lifting a bit.
I was on a long trip, and the engine was already heated up, so it had a lot of power. We were the only two cars, except for a semi we had just passed, for as far as I could see or else I would have never attempted it. Not something I would do again.
155 is really not that impressive, honestly. I had my 1988 6-cyl Toyota Corolla up to 140mph way back when (upstate NY on the thruway). Of course, it was shaking like crazy and felt far more unstable than the SC430. Just about any decent car should be able to reach those speeds.
The acceleration power is the real measurement, IMHO. At least on my SC430, this seems so inconsistent. Sometimes, I can get up to 50mph from a light change before hitting the other side of the intersection and other times, it feels like it is working its butt off just trying to get up to 45. I never participate when people try to challenge because of that. I never know what I am going to get. It's a bit embarrassing when trying to pass on the highway and it decides it wants to be a sloth. Yet, other times, I press the pedal and off it goes. Very inconsistent. And very frustrating.
I've read somewhere that the top speed of the stock SC430 is 210MPH (not sure if that applies to the -2005 model years). That would be impressive (if the car -and tires- could actually handle it)
05-14-18, 02:17 PM
#21
And how do you expect me to "explain that"? The information I gave you is all that I have. I was driving, not doing a science experiment. Maybe I am wrong and it wasn't due to overheating, but the sequence of events were: Drove 155 mph for 5 minutes, TPMS warning went off. I pulled off the highway. Tires were extremely hot. Pressure was 10lbs. (12lbs actually) less in front passenger tire than all other tires. I know I lost 12lbs of pressure because I had just checked them to make sure they were balanced before the trip. I had them all at 40lbs and the front passenger tire was at 28lbs when the warning sensor went off and I had to get off the highway. It happened while I was travelling 155 mph despite having driven nearly 80 miles prior to that. And it didn't happen again after refilling them despite driving another 100+ miles on that trip. Maybe the seals around the sensor opened under the increased pressure. I couldn't tell you. I forgot to bring my scientific instruments with me. I had a hand to sense temperature and a tire pressure gauge with me and the sequence of events lead me to deduce what had just happened.
That's the information I have to give you. I'm afraid that's all there is.
Wait... What? You don't think driving down a highway straight at high speeds causes friction which generates heat? How do you obtain traction without friction? You are correct, of course, that higher temperatures would increase air pressure. Perhaps the pressure exceeded the max pressure and something momentarily gave out? Maybe the seals around the sensors? Maybe the grip to the hub? Maybe uneven wear on the tire caused more friction than the others? Perhaps there is a defect in that tire, but it only came out during high speeds? No idea. I drove 155mph. TPMS warning tripped. I pulled off the highway. Touched tires and they were hot enough to burn my hand if I kept it on them. Measured tire pressure. FR tire was 12lbs less than it was when I started out on the trip. Other tires were still 40lbs.
That's the full extent of my measurements.
Huh? Because we have a tire pressure warning system in the SC430 which is triggered by a significant differential in tire pressure among the tires or a sudden loss of pressure or increase in temperature. The dash light comes on when a tire pressure is below a certain point gradually and the light as well as a warning buzzer comes on when the drop is sudden or temps exceed some amount. The buzzer went off, indicating that the loss of pressure (or rise in temp) was sudden. No magic or psychic powers were involved.
It doesn't make sense? Well, it happened, so I don't know what to tell you. It was nearly two years ago now and it has not happened since despite doing nothing else to the tires or sensors since. Are you doubting it happened or just unsatisfied with my lack of scientific measurements in my anecdote? I'm afraid that either way, you are going to be left unsatisfied or doubtful. *shrug*
That's the information I have to give you. I'm afraid that's all there is.
That's the full extent of my measurements.
It doesn't make sense? Well, it happened, so I don't know what to tell you. It was nearly two years ago now and it has not happened since despite doing nothing else to the tires or sensors since. Are you doubting it happened or just unsatisfied with my lack of scientific measurements in my anecdote? I'm afraid that either way, you are going to be left unsatisfied or doubtful. *shrug*
05-14-18, 05:00 PM
#22
Lexus Test Driver
Retro, I am so glad you didn’t have a blowout at that speed! According to this article, you were on the verge of a blowout!
https://www.aceable.com/blog/this-is...s-get-too-hot/
Tires can fail during periods of excessive heat. Due to increased friction, high-speed driving, excessive cornering and frequent braking during periods of very high temperatures can cause the tire to heat up beyond their design ratings. Once this happens, a blowout can occur.
http://www.startribune.com/extreme-h...outs/49347922/
A 225/45/ZR17 tire could be considered a standard front tire in a Boxster, Cayman or Carrera. This particular tire has a 25 inch overall diameter and after doing the math we know that this tire will turn approximately 807 times every mile. At 25 miles per hour this tire will roll 5.6 times per second, at 70 mph (speed limit on the Interstate) it will roll15.7 times per second and at 140 mph (speed right before braking for turn 17 at Sebring) the tire will roll a daunting 31.4 times every second. This means that the tire is changing its shape from its unloaded to its loaded state and back every 3/100th of a second.
This constant tire deflection plus the friction of the tire against the road (track) generates tremendous heat build-up in the tires. Since the tires are filled with air (or nitrogen) which is a gas, Boyles Law demonstrates that if the volume of gas is maintained constant, its pressure is directly proportional to its temperature, therefore your tire pressure will go up as the tire gets used, and the faster the tires spin, the faster the temperature and therefore the pressure will build up.
http://www.pedrosgarage.com/Site_5/T...igh_Speed.html
https://www.aceable.com/blog/this-is...s-get-too-hot/
Tires can fail during periods of excessive heat. Due to increased friction, high-speed driving, excessive cornering and frequent braking during periods of very high temperatures can cause the tire to heat up beyond their design ratings. Once this happens, a blowout can occur.
http://www.startribune.com/extreme-h...outs/49347922/
A 225/45/ZR17 tire could be considered a standard front tire in a Boxster, Cayman or Carrera. This particular tire has a 25 inch overall diameter and after doing the math we know that this tire will turn approximately 807 times every mile. At 25 miles per hour this tire will roll 5.6 times per second, at 70 mph (speed limit on the Interstate) it will roll15.7 times per second and at 140 mph (speed right before braking for turn 17 at Sebring) the tire will roll a daunting 31.4 times every second. This means that the tire is changing its shape from its unloaded to its loaded state and back every 3/100th of a second.
This constant tire deflection plus the friction of the tire against the road (track) generates tremendous heat build-up in the tires. Since the tires are filled with air (or nitrogen) which is a gas, Boyles Law demonstrates that if the volume of gas is maintained constant, its pressure is directly proportional to its temperature, therefore your tire pressure will go up as the tire gets used, and the faster the tires spin, the faster the temperature and therefore the pressure will build up.
http://www.pedrosgarage.com/Site_5/T...igh_Speed.html
05-14-18, 05:09 PM
#23
Retro, I am so glad you didn’t have a blowout at that speed! According to this article, you were on the verge of a blowout!
https://www.aceable.com/blog/this-is...s-get-too-hot/
Tires can fail during periods of excessive heat. Due to increased friction, high-speed driving, excessive cornering and frequent braking during periods of very high temperatures can cause the tire to heat up beyond their design ratings. Once this happens, a blowout can occur.
http://www.startribune.com/extreme-h...outs/49347922/
A 225/45/ZR17 tire could be considered a standard front tire in a Boxster, Cayman or Carrera. This particular tire has a 25 inch overall diameter and after doing the math we know that this tire will turn approximately 807 times every mile. At 25 miles per hour this tire will roll 5.6 times per second, at 70 mph (speed limit on the Interstate) it will roll15.7 times per second and at 140 mph (speed right before braking for turn 17 at Sebring) the tire will roll a daunting 31.4 times every second. This means that the tire is changing its shape from its unloaded to its loaded state and back every 3/100th of a second.
This constant tire deflection plus the friction of the tire against the road (track) generates tremendous heat build-up in the tires. Since the tires are filled with air (or nitrogen) which is a gas, Boyles Law demonstrates that if the volume of gas is maintained constant, its pressure is directly proportional to its temperature, therefore your tire pressure will go up as the tire gets used, and the faster the tires spin, the faster the temperature and therefore the pressure will build up.
http://www.pedrosgarage.com/Site_5/T...igh_Speed.html
https://www.aceable.com/blog/this-is...s-get-too-hot/
Tires can fail during periods of excessive heat. Due to increased friction, high-speed driving, excessive cornering and frequent braking during periods of very high temperatures can cause the tire to heat up beyond their design ratings. Once this happens, a blowout can occur.
http://www.startribune.com/extreme-h...outs/49347922/
A 225/45/ZR17 tire could be considered a standard front tire in a Boxster, Cayman or Carrera. This particular tire has a 25 inch overall diameter and after doing the math we know that this tire will turn approximately 807 times every mile. At 25 miles per hour this tire will roll 5.6 times per second, at 70 mph (speed limit on the Interstate) it will roll15.7 times per second and at 140 mph (speed right before braking for turn 17 at Sebring) the tire will roll a daunting 31.4 times every second. This means that the tire is changing its shape from its unloaded to its loaded state and back every 3/100th of a second.
This constant tire deflection plus the friction of the tire against the road (track) generates tremendous heat build-up in the tires. Since the tires are filled with air (or nitrogen) which is a gas, Boyles Law demonstrates that if the volume of gas is maintained constant, its pressure is directly proportional to its temperature, therefore your tire pressure will go up as the tire gets used, and the faster the tires spin, the faster the temperature and therefore the pressure will build up.
http://www.pedrosgarage.com/Site_5/T...igh_Speed.html
Last edited by Retroplay; 05-14-18 at 05:13 PM.
05-15-18, 11:22 AM
#24
Pole Position
That would make sense. If the pressure built up in your tire, it could compress the valve stem/tpms gasket and let air out. Losing 12 pounds that fast would indicate it was a pretty big air release and the gasket would make sense.
04-22-21, 10:20 AM
#25
Pole Position
Thread Starter
I just did 95mph yesterday with open roof and all the windows down. Let me tell you, it's quite an experience which I have never felt before. Loved it. I have driven 100 mph, but with top up, all windows up, and it’s completely different feeling.
Anyone's done higher speed with top and windows down?
Anyone's done higher speed with top and windows down?
Last edited by GmanSC; 04-22-21 at 02:00 PM.
04-22-21, 11:04 AM
#26
I just did 95mph yesterday with open roof and all the windows down. Let me tell you, it's
quite an experience, I have never felt before. Love it.
I have driven 100 mph, but with top up, all windows up, and it’s completely feelings.. Anyone's done higher speed with top and windows down?
quite an experience, I have never felt before. Love it.
I have driven 100 mph, but with top up, all windows up, and it’s completely feelings.. Anyone's done higher speed with top and windows down?
Went 120 or so.
cars patented body lines did well for cabin airflow at speed.
Would not recommend high speeds without major suspension work.
04-22-21, 06:27 PM
#28
Pole Position
Thread Starter
