60-130 MPH: New performance measurement!
#47
Originally posted by Bill S
I agree, but under the most common conditions (e.g., not obese or going downhill or at 7000 ft), these variables are usually negligible. For example, I timed several runs with my 130 lb wife in and out of the car. There was virtually no difference in the 60 to 130 times.
I agree, but under the most common conditions (e.g., not obese or going downhill or at 7000 ft), these variables are usually negligible. For example, I timed several runs with my 130 lb wife in and out of the car. There was virtually no difference in the 60 to 130 times.
Density altitude is computed using pressure altitude and temperature. On a cold day here in Atlanta the density altitude can be over a thousand feet lower. On a hot day it can be 2000' higher, a swing of over 3000', which would make a difference in times.
As for weight, every ~200 lbs makes ~ 0.1 sec. difference in quarter mile times, so that much might also be expected in a 60-130 run.
Combine these (one car on a 2% upslope on a hot day at 1000' MSL with a full tank of gas, versus another car on a 2% downslope on a cold day at sea level with an eighth of a tank of gas) and the the results could not be compared with any real results gained.
#48
AX22
I have the AX22 GPS/accelerometer based performance meter and here's a recent graph I did while testing it in my Ruf'd GT2.
Sadly my hard-disk on my PC failed so I've lost the data, so cannot extract any performance times.
I will say that GPS or accelerometer is the only way to do it accurately, as I've seen Porsche speedos vary wildly in error.
Guy
Sadly my hard-disk on my PC failed so I've lost the data, so cannot extract any performance times.
I will say that GPS or accelerometer is the only way to do it accurately, as I've seen Porsche speedos vary wildly in error.
Guy
#49
Originally posted by Dock (Atlanta)
Combine these (one car on a 2% upslope on a hot day at 1000' MSL with a full tank of gas, versus another car on a 2% downslope on a cold day at sea level with an eighth of a tank of gas) and the the results could not be compared with any real results gained.
Combine these (one car on a 2% upslope on a hot day at 1000' MSL with a full tank of gas, versus another car on a 2% downslope on a cold day at sea level with an eighth of a tank of gas) and the the results could not be compared with any real results gained.
If your time is slower than you expect, just try again under better conditions and report the change. In any case, you're not going to get a time under 7 seconds unless you have a very fast car.
#50
Re: AX22
Originally posted by Guy
I will say that GPS or accelerometer is the only way to do it accurately, as I've seen Porsche speedos vary wildly in error.
Guy
I will say that GPS or accelerometer is the only way to do it accurately, as I've seen Porsche speedos vary wildly in error.
Guy
#51
Originally posted by MBailey
Bill S,
Maybe I missed this earlier in the thread, but how do you measure your 60-130 runs?
Bill S,
Maybe I missed this earlier in the thread, but how do you measure your 60-130 runs?
#52
If you read the Race Technology Website it explains all (the 5 Hz GPS, the doppler effect interpolation and also the g-meter accelerometer overlay). The short answer is it gets down to 0.01 seconds.
Its accurate enough to be used by a few car manufacturers and some car magazines.
It also produces a full acceleration matrix ie from every 10mph increment to every other 10mph increment both accelerating and decelerating.
When I get a chance I'll use it again and post some more results.
Rgds
Guy
Its accurate enough to be used by a few car manufacturers and some car magazines.
It also produces a full acceleration matrix ie from every 10mph increment to every other 10mph increment both accelerating and decelerating.
When I get a chance I'll use it again and post some more results.
Rgds
Guy
#56
Great to see this old thread!
I only had an ECU job in those days. On a real cold night I got ~around a 9.2s measuring with an old G-Tech accelerometer. The G-techs were not very accurate because when the nose came up during hard accelleration the unit sensed more gs than were really present. The GPS measurers are certainly a vast improvement.
I only had an ECU job in those days. On a real cold night I got ~around a 9.2s measuring with an old G-Tech accelerometer. The G-techs were not very accurate because when the nose came up during hard accelleration the unit sensed more gs than were really present. The GPS measurers are certainly a vast improvement.