for the non believers
03-19-2004, 09:37 PM
#31
Drifting
MPH per '000
Speed/Rev Table
I know it's for European cars, but it may help all the same.
It looks to me like 4,800 should equal 150 rather than 161mph assuming 31.25 per 1000 is correct on the 86.5 Auto.
On the 82 Manual 4,900 should equal 135, which is as shown.
Obviously tyre size will affect actual speed, but not indicated.
I know it's for European cars, but it may help all the same.
It looks to me like 4,800 should equal 150 rather than 161mph assuming 31.25 per 1000 is correct on the 86.5 Auto.
On the 82 Manual 4,900 should equal 135, which is as shown.
Obviously tyre size will affect actual speed, but not indicated.
03-19-2004, 10:51 PM
#33
Nordschleife Master
Well, I ran the numbers and actually things look OK. The A28.07 tranny is shown in the PET to have a 33:15 final drive or a scant 2.2 ratio. Working back from Paul's data 265 kph would be 4949 rpm. That's a bit more than is shown. I'd chalk it up to an over-eager speedo.
It only takes two straight miles to get these things going like that.
It only takes two straight miles to get these things going like that.
03-20-2004, 01:02 AM
#34
Racer
Join Date: Sep 2003
Location: Los Angeles, CA
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i have a video of me going 120 in the desert next to a Nissan Maxima, but I have no way of putting it on the internet. I also have footage of me being passed....twice by a Ferrari 575m Maranello, but i guess the 12 cylinder engine and like 500 horses justify that...
03-20-2004, 01:16 AM
#36
Burning Brakes
In reading that tech table, it says that my S4 can go 69.8mph in 2nd gear under maximum engine power. Now I've checked this before, and I've had the speedo hit 88 in 2nd gear. My car isn't stock, and the rear tires were 255/45/16s at the time. Now having that in mind and knowing that the speedo isn't 100% accurate, is there a way to determine my engine power to get top out 2nd at 88mph? '87 automatic.
03-20-2004, 10:43 AM
#37
Addict
Rennlist Member
Rennlist Member
Second-gear top speed shouldn't be limited by engine power, but by revs. That is, your S4 should have more than ample power to blow right past redline in second. So no.
If your car does 88 at redline in second, it's geared differently than the 5-speed cars referenced in the table. (Which, being a 4-speed auto, it is!)
[EDIT] I just found the auto trans chart. The discrepancy between your top speed in 2nd and the chart's "MPH at max engine power" in second is accounted for in part by what Dave points out in the following post: max engine power is developed (according to the chart) at 6000 while redline is 6600. Still, the auto S4 referenced in the chart should (by my math) do 77 mph in second (~70 / 6000 X 6600), instead of your 88. So your auto S4 appears to be geared differently than S4s in the UK.
Do Euro S4s have different rear end ratios than US cars?
If your car does 88 at redline in second, it's geared differently than the 5-speed cars referenced in the table. (Which, being a 4-speed auto, it is!)
[EDIT] I just found the auto trans chart. The discrepancy between your top speed in 2nd and the chart's "MPH at max engine power" in second is accounted for in part by what Dave points out in the following post: max engine power is developed (according to the chart) at 6000 while redline is 6600. Still, the auto S4 referenced in the chart should (by my math) do 77 mph in second (~70 / 6000 X 6600), instead of your 88. So your auto S4 appears to be geared differently than S4s in the UK.
Do Euro S4s have different rear end ratios than US cars?
Last edited by MBMB; 03-20-2004 at 02:10 PM.
03-20-2004, 03:10 PM
#39
Rennlist Member
Porsche Speedos are OVERLY optismistic at the higher speeds. Always go off the tach signal, gear ratio and tire size.
To get much better resolution on this topic, get the actual rolling distance of the tire by paint dotting the tir5e, roll it, andmeasure the distance between dots.....taht is the true rolling diameter, then use the math to go from there.
Regards,
Marc
DEVEK
To get much better resolution on this topic, get the actual rolling distance of the tire by paint dotting the tir5e, roll it, andmeasure the distance between dots.....taht is the true rolling diameter, then use the math to go from there.
Regards,
Marc
DEVEK
03-20-2004, 04:09 PM
#40
Andrew,
My 82', Weissach, auto -stock- runs the same temperature reading at 137-138 mph (indicated), 5300-5400rpm (indicated) after a 25 mile warm up and using kick-down from about a 15mph roll.
This is more of a question than a ding - Guru's?
About driven gears:
1. Would I be wrong in assuming that in both the 5 spd and the auto's that the 'top' gear is usually underdriven i.e., not enough HP/Torque to overcome wind/road resistance at a certain point, thus preventing the car from attaining the max mph that the top gear ratio is mathematically capeable of?
2. Would I be wrong in assuming that the lower gears -1,2,3,4 -, generally, CAN be driven to the maximum mph for that gear set's ratio, and that pushing the engine beyond the max mph possible results in little if anything and will generally over-rev the engine?
3. Assuming the gear sets in the 5spd's are close at final ratio (1:1).
And I know that the 81 thru 84 5 spds, are as follows:
G28.05 G28.07 G28.08
1st > 3.6010 >3.7645 >4.2705
2nd > 2.4646 >2.5122 >2.8498
3rd > 1.8194 >1.7900 >2.0306
4th > 1.3433 >1.3541 >1.5361
The 81 - 82 models were rated by Porsche to swim up to 230 km/h or 143mph
The 81 - 82 - 83 S models were rated at 250km/h or 155mph, with U.S. versions paddling along at 235km/h or 146mph.
The 84 S models pushed 255km/h or 158mph with the U.S. version was 235km/h or 146mph.
These are max speed(rpm) runs at 1/2 DIN weights.
So can any of these sHARKs pull 230 km/h in third without scattering expensive engine components?
Are any of the 86 thru 95 5spds capeable of pulling 230 km/h, 143 mph in third, even mathematically?
I know that the indicated rpm/mph readings I did off of Pattycakes don't jibe with the Porsche data and gradient charts either.
So while this looks like I'm hackin' on Lizard my data is off -not as much- what I'm after is this:
1. Can any of the sHARKs pull 143/145 mph in 3rd?
2. While it is obvious that getting a SC system installed is going to change the 0 - 60 and 1/4 mile times significantly will any of the gears with the exception of 5th actually go faster?
And in the case of 5th will there be a 1,3 5, 10 15 mph difference top end?
My 82', Weissach, auto -stock- runs the same temperature reading at 137-138 mph (indicated), 5300-5400rpm (indicated) after a 25 mile warm up and using kick-down from about a 15mph roll.
This is more of a question than a ding - Guru's?
About driven gears:
1. Would I be wrong in assuming that in both the 5 spd and the auto's that the 'top' gear is usually underdriven i.e., not enough HP/Torque to overcome wind/road resistance at a certain point, thus preventing the car from attaining the max mph that the top gear ratio is mathematically capeable of?
2. Would I be wrong in assuming that the lower gears -1,2,3,4 -, generally, CAN be driven to the maximum mph for that gear set's ratio, and that pushing the engine beyond the max mph possible results in little if anything and will generally over-rev the engine?
3. Assuming the gear sets in the 5spd's are close at final ratio (1:1).
And I know that the 81 thru 84 5 spds, are as follows:
G28.05 G28.07 G28.08
1st > 3.6010 >3.7645 >4.2705
2nd > 2.4646 >2.5122 >2.8498
3rd > 1.8194 >1.7900 >2.0306
4th > 1.3433 >1.3541 >1.5361
The 81 - 82 models were rated by Porsche to swim up to 230 km/h or 143mph
The 81 - 82 - 83 S models were rated at 250km/h or 155mph, with U.S. versions paddling along at 235km/h or 146mph.
The 84 S models pushed 255km/h or 158mph with the U.S. version was 235km/h or 146mph.
These are max speed(rpm) runs at 1/2 DIN weights.
So can any of these sHARKs pull 230 km/h in third without scattering expensive engine components?
Are any of the 86 thru 95 5spds capeable of pulling 230 km/h, 143 mph in third, even mathematically?
I know that the indicated rpm/mph readings I did off of Pattycakes don't jibe with the Porsche data and gradient charts either.
So while this looks like I'm hackin' on Lizard my data is off -not as much- what I'm after is this:
1. Can any of the sHARKs pull 143/145 mph in 3rd?
2. While it is obvious that getting a SC system installed is going to change the 0 - 60 and 1/4 mile times significantly will any of the gears with the exception of 5th actually go faster?
And in the case of 5th will there be a 1,3 5, 10 15 mph difference top end?
03-21-2004, 01:19 AM
#41
Nordschleife Master
Thread Starter
Marc, I have checked the speedo as stated in a rural area and it reads slow at lower speeds, it is very possible for it to read optimisticly, however I am going to be getting a GPS to confirm it, just didnt have 1 on that trip, and I will get a pic of the GPS, and then moving over to the speedo to see how acurrate it really is, also as stated I have 245/50ZR16 on it which are abit bigger than the factory and are causing about a 3.2% increase in actual speed
but yah glen it only took me about 2 miles to do that entering at 120kmph, pretty impressive eh,
but yah glen it only took me about 2 miles to do that entering at 120kmph, pretty impressive eh,
03-21-2004, 12:49 PM
#42
928 Collector
Rennlist Member
Rennlist Member
Lizard I do 120 almost daily in my S4, it takes no more than a romp on the gas and under a 1/4-mile from a running start. So, I have no problems believing my eyes on your video. Also, from Euro experience, cars like ours when given open road, will just continue accelerating. I have little doubt that my car, given open road and a firm gas foot, would exceed 160mph any day and likely far more. All it takes is time and lack of blue lights.
03-21-2004, 12:55 PM
#43
Hey Beej,
Your 87 should easily do more than 70 in 2nd. My old 87..at the track..with slightly larger rear tires almost did the quarter in two gears....I think I got about 95mph or so..before the revlimiter hit..(modified with chips..at 6800rpm I think).
I was trying to see if I could pull of a two shift 1/4...but didn't quite make it..and shifted to 3rd...just before the end....my time was still 14.2 or so...and that was just sort of coasting through....
Bet I would have had mid 13s if the tires were just a bit taller.. ;-) ;-)
Later,
Tom
Your 87 should easily do more than 70 in 2nd. My old 87..at the track..with slightly larger rear tires almost did the quarter in two gears....I think I got about 95mph or so..before the revlimiter hit..(modified with chips..at 6800rpm I think).
I was trying to see if I could pull of a two shift 1/4...but didn't quite make it..and shifted to 3rd...just before the end....my time was still 14.2 or so...and that was just sort of coasting through....
Bet I would have had mid 13s if the tires were just a bit taller.. ;-) ;-)
Later,
Tom