944/951 Fast?
10-10-2004, 03:42 PM
#46
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Justin: That's a good link, but isn't accurate because.....
That may explain why sometimes the car reaches top speed during certain times so fast, while other times it seems 'slower' if you know what i mean 
Why isn't it perfectly accurate?
There are far too many factors that affect a car's velocity to be reasonably considered in this table. Barometric pressure and altitude all contribute to a variable air pressure that affects the external pressure on the tire, reducing its size and reducing the vehicle's velocity. The tire size is also affected by other factors like temperature, humidity, car weight, car weight distribution, weight shifting caused by acceleration, and rotational speed (centrifugal force). Gravitational forces from the earth, moon, and sun also affect the pressure on the tire and its size.
There are far too many factors that affect a car's velocity to be reasonably considered in this table. Barometric pressure and altitude all contribute to a variable air pressure that affects the external pressure on the tire, reducing its size and reducing the vehicle's velocity. The tire size is also affected by other factors like temperature, humidity, car weight, car weight distribution, weight shifting caused by acceleration, and rotational speed (centrifugal force). Gravitational forces from the earth, moon, and sun also affect the pressure on the tire and its size.
10-10-2004, 04:07 PM
#47
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10-10-2004, 04:09 PM
#48
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Oh MAn!!!!
Originally Posted by lart951
10-10-2004, 04:48 PM
#49
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Man, you guys oughta have something like the Texas Mile. I just rode shotgun/ navigator with Brian (Red1) yesterday, and it was a BLAST, even though Brian would argue my navigational skills (his "directions" were GHETTO-fabulous)! They do runs down an old airport runway with the traps set at 1 mile. It's a really SAFE, affordable way to see what she'll do without risking jail time or a vehicular manslaughter rap.
There were 2 other 951's there and the black chipped one was hitting the traps at 146+/-. The groovy green stocker was 141-ish. Brian only ran twice with some clutch slippage, so his times weren't really an accurate idea of what his red rocket will do. There was this one cat in a twin turbo 924 that was BOMBING down the track at something like 210, though...
Yes, speedo's are painfully optimistic in damn near every car ever made, let alone 15 year old sports cars.
There were 2 other 951's there and the black chipped one was hitting the traps at 146+/-. The groovy green stocker was 141-ish. Brian only ran twice with some clutch slippage, so his times weren't really an accurate idea of what his red rocket will do. There was this one cat in a twin turbo 924 that was BOMBING down the track at something like 210, though...
Yes, speedo's are painfully optimistic in damn near every car ever made, let alone 15 year old sports cars.
10-10-2004, 04:55 PM
#50
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Hosrom, yes calculating top speed from ratios isn't perfect, but it's a darn site better than reading it from the speedo.
951power's numbers are reasonable, because he was using GPS and at 6800 RPM he is going exactly as fast as he should. Every time a thread like this comes up, there are a few people who report their top speed from the gauge... there is a great example of a picture on an earlier page of a speedo at 170Mph and the RPM well below the redline.
Justin
951power's numbers are reasonable, because he was using GPS and at 6800 RPM he is going exactly as fast as he should. Every time a thread like this comes up, there are a few people who report their top speed from the gauge... there is a great example of a picture on an earlier page of a speedo at 170Mph and the RPM well below the redline.
Justin
10-10-2004, 05:44 PM
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If you refer to the transmission diagram on page 118 of your owner's manual, it indicates a theoretical 283km/hr at 6800 rpm on stock wheels, so 951power's GPS reading is bang on.
10-11-2004, 05:33 AM
#52
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OK...lemme get this clear: what is the bone-stock speedometer accuracy differential?
1986 944 Turbo - Factory stock, except for KKK/BB rebuild, ride lowered 1"
Wheels - F=215/55/ZR15; R=225/50/ZR16
1986 944 Turbo - Factory stock, except for KKK/BB rebuild, ride lowered 1"
Wheels - F=215/55/ZR15; R=225/50/ZR16
10-11-2004, 09:06 AM
#54
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Originally Posted by gilwong
If you refer to the transmission diagram on page 118 of your owner's manual, it indicates a theoretical 283km/hr at 6800 rpm on stock wheels, so 951power's GPS reading is bang on.
Also did a test of my 83-na some years back, it showed 239kph on the gps , speedo showing 255kph (stock). With "original" porsche cup 1 wheels fitted it only did a 235 at speddo and 223 on the gps. ( 225/45/17 in front and 255/40/17 in back)... and it took a much longer time to get there..
also the speedo is very accurate up to 100kph on both cars.. but from there on the differential gets bigger between gps and speedo, but its not a linear difference.
10-11-2004, 12:30 PM
#55
so, the speedo reads its speed by the rate at which the tires are spinning correct? there isnt some timming thing shooting at the ground or some gps that reads the time i assume. so, if the first is correct, think you could use that excuse as a way to get out of a ticket?
"well you see officer, i have larger wheels and the speedo has not been updated for them so... so, you see, if it says im running 130 on the speedo, it is most likely faster, so i could not tell my real speed."
"uhhh.... fix your speedo, next time you get the ticket"
"well you see officer, i have larger wheels and the speedo has not been updated for them so... so, you see, if it says im running 130 on the speedo, it is most likely faster, so i could not tell my real speed."
"uhhh.... fix your speedo, next time you get the ticket"
10-11-2004, 01:42 PM
#56
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Yes Kesepton you could use that excuse....but, not at a buck thirty.lol.
Maybe going 80 and your speedo might be off 10 so you tell the cop you thought you were going 70mph.....and your real sorry. You have a appointment with porsche on thursday to get the new tires and tranny calibrated so that this will not happen again.
Maybe going 80 and your speedo might be off 10 so you tell the cop you thought you were going 70mph.....and your real sorry. You have a appointment with porsche on thursday to get the new tires and tranny calibrated so that this will not happen again.
10-11-2004, 03:21 PM
#58
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lol......most of them don't know **** about porsche's. You could tell them whatever you wanted and if you sold it right they wouldn't have a problem believing you. I am very cordial and nice and respectful and they let me go. I have been let go plenty of times.
10-11-2004, 04:19 PM
#59
I get tickets when I get pulled over, whether I am nice or whether I'm a smartass (I've tried both).
Do you know why i pulled you over?
i have NO idea officer, none whatsoever, why DID you pull me over?
Do you know why i pulled you over?
i have NO idea officer, none whatsoever, why DID you pull me over?
10-11-2004, 04:27 PM
#60
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lol....nice one randy.
Sometimes I get written up but, most of the time I get left off(not that I get pulled over that often...cause I don't. hehe)
Maybe its the porsche the smile and the suit. Who knows.
Sometimes I get written up but, most of the time I get left off(not that I get pulled over that often...cause I don't. hehe)
Maybe its the porsche the smile and the suit. Who knows.