What do I need to do 200 mph SAFELY?
10-27-04, 03:15 AM
#76
Originally Posted by '98 Type RS
5th gear with stock power will not get to redline mostly because of wind resistance. Once you are at redline in a gear, having more hp will not get you any more speed.
10-27-04, 10:12 AM
#78
Super Snuggles
Originally Posted by patman
tire diameter(feet)* pi * rpm * gear ratio (tranny) * gear ratio(rear)*0.01136364 (ftm/mph)= speed
(24.8" tire = 2.066 feet diameter)
2.066 * 3.14159 * 8,000 * 0.72 * 4.10 * 0.01136364 = 1,742 mph
2.066 * 3.14159 * 8,000 / 0.72 / 4.10 * 0.01136364 = 200 mph
10-27-04, 10:52 AM
#80
Super Snuggles
Originally Posted by patman
sorry if i confused ya.
Most people would not know to use "1/0.72", because gear ratios are almost exclusively listed as decimals, not fractions.
10-27-04, 02:22 PM
#83
Super Snuggles
Originally Posted by patman
oh well my bad. guess i dont know what other people know. wrote that on my way out the door to class in about 30 seconds anyway.
Originally Posted by FDNewbie
So the stock gearing WILL take you to 200mph, huh?!
If you calculate the theoretical gear-limited top speed at redline for 3rd or 4th gear for your car, you can test this quickly and relatively safely. If you accelerate to redline in that gear and note your mph, you will not be traveling at the speed your calculations indicated, despite the fact that you have more than enough power to reach it. Why?
The reason is that traction is never really 100%, there are always inaccuracies in analog gauges, and you need to use the actual measured circumference of your mounted tires to increase the precision of your calculations. Bottom line, you'll always need more gear than you'll actually "use" to reach a given speed.
10-27-04, 02:39 PM
#84
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Actually, you have to think that the tire will expand at those speeds and will actually be larger...
Now Ill be running a .5 OD (t-56) and an auto rear (3.90s) so the gearing will not be a problem for me...
I just wateched the vid of the RX flipping at 210... Im a little scared....
Now Ill be running a .5 OD (t-56) and an auto rear (3.90s) so the gearing will not be a problem for me...
I just wateched the vid of the RX flipping at 210... Im a little scared....
10-27-04, 02:49 PM
#85
Super Snuggles
Originally Posted by payne
Actually, you have to think that the tire will expand at those speeds and will actually be larger...
10-27-04, 03:31 PM
#87
haha.
you said you have a T56 in your car? Borg-Warner? I have wanted to do that in my fc for a long time, waiting till i kill my driveshaft and need a custom one...how hard was it to get the rx7 bellhousing on there? did you have to change the shifter hole?
you said you have a T56 in your car? Borg-Warner? I have wanted to do that in my fc for a long time, waiting till i kill my driveshaft and need a custom one...how hard was it to get the rx7 bellhousing on there? did you have to change the shifter hole?
10-27-04, 03:52 PM
#88
Originally Posted by jimlab
Not necessarily. Even after you have enough power to overcome the losses due to air resistance, rolling resistance, and drivetrain friction at that speed, you'll still have some percentage of tire slip and other factors (including the fact that a mounted tire isn't perfectly round) that keep you from reaching your calculated maximum speed.
If you calculate the theoretical gear-limited top speed at redline for 3rd or 4th gear for your car, you can test this quickly and relatively safely. If you accelerate to redline in that gear and note your mph, you will not be traveling at the speed your calculations indicated, despite the fact that you have more than enough power to reach it. Why?
The reason is that traction is never really 100%, there are always inaccuracies in analog gauges, and you need to use the actual measured circumference of your mounted tires to increase the precision of your calculations. Bottom line, you'll always need more gear than you'll actually "use" to reach a given speed.
If you calculate the theoretical gear-limited top speed at redline for 3rd or 4th gear for your car, you can test this quickly and relatively safely. If you accelerate to redline in that gear and note your mph, you will not be traveling at the speed your calculations indicated, despite the fact that you have more than enough power to reach it. Why?
The reason is that traction is never really 100%, there are always inaccuracies in analog gauges, and you need to use the actual measured circumference of your mounted tires to increase the precision of your calculations. Bottom line, you'll always need more gear than you'll actually "use" to reach a given speed.
10-27-04, 05:10 PM
#89
Super Snuggles
Originally Posted by patman
how hard was it to get the rx7 bellhousing on there? did you have to change the shifter hole?
10-27-04, 05:16 PM
#90
oh. well..mine will be, eventually. i checked one out...looked like it would fit without too much problem.. the bellhousing was the only complicated-looking part....my plan was to weld the front half of a fc bellhousing to the back half of a camaro one.
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