Drivetrain Screw the Dyno!
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OVERDRIVE
Joined: May 2003
Posts: 7,926
Likes: 40
From: Greensboro, NC
Were you going in the same direction? You noted an incline. Running both ways to average out your time may help. What year is your Mini?
Originally Posted by rajron
So I got new tires, the OEM run-flats were bald on the front, the backs were OK but I got rid of them.
Anyway the new tires are 205/50/16’s as opposed to the 195/55/16 OEM.
My 3500 RPM to 6000 RPM times have changed.
Conditions were very similar to the first time I did the run see below:
• No wind
• 38°F
• 5829 ft above sea level
• <0.5° incline
• 3500 RPM = 47 mph
• 6000 RPM = 77 mph
• 3 passes
o 7.49 seconds
o 7.25 seconds
o 7.62 seconds
Today on the same stretch of road near Double Eagle Airport above Albuquerque:
• Again no wind, or very light winds
• 39°F
• 3500 RPM = about 46 mph (GPS) – did not check 6000 RPM
• 3 passes
• 7.08
• 6.95
• 7.05
Nearly half a second difference?
Must be the tires or the gas (winter gas?), I know my stop watch didn’t change.
Anyway the new tires are 205/50/16’s as opposed to the 195/55/16 OEM.
My 3500 RPM to 6000 RPM times have changed.
Conditions were very similar to the first time I did the run see below:
• No wind
• 38°F
• 5829 ft above sea level
• <0.5° incline
• 3500 RPM = 47 mph
• 6000 RPM = 77 mph
• 3 passes
o 7.49 seconds
o 7.25 seconds
o 7.62 seconds
Today on the same stretch of road near Double Eagle Airport above Albuquerque:
• Again no wind, or very light winds
• 39°F
• 3500 RPM = about 46 mph (GPS) – did not check 6000 RPM
• 3 passes
• 7.08
• 6.95
• 7.05
Nearly half a second difference?
Must be the tires or the gas (winter gas?), I know my stop watch didn’t change.
3rd Gear
Joined: Oct 2003
Posts: 183
Likes: 0
From: PHX area
So when I realized my times were slow I decided to go back to the same stretch of road to double check my times. Sure enough it didn’t matter what direction I traveled my times were about the same.
As a matter of fact I went to a location south of this area where altitude was about 5000 feet, at that location my times dropped nearly .5 seconds as well. But for comparison between tires I chose the stretch of road near Double Eagle Airport which is near by.
Oh I have an early 2004.
As a matter of fact I went to a location south of this area where altitude was about 5000 feet, at that location my times dropped nearly .5 seconds as well. But for comparison between tires I chose the stretch of road near Double Eagle Airport which is near by.
Oh I have an early 2004.
6th Gear
Joined: Oct 2002
Posts: 3,652
Likes: 6
From: Lansdale, PA
FWIW, here's some guys doing a kind-of similar thing with Audi S4's, although they are datalogging instead of using stopwatches and hand-eye coordination:
http://fats.audi-quattro.org/info.php
http://fats.audi-quattro.org/info.php
6th Gear
Joined: Sep 2004
Posts: 5,149
Likes: 0
Originally Posted by andy@ross-tech.com
I did a pair of 3500-6000 runs in 3rd gear during lunch. It was a level surface, and I did one run in each direction. I datalogged RPM and got:
Run 1: 5.467 s
Run 2: 5.410 s
Run 1: 5.467 s
Run 2: 5.410 s
6th Gear
Joined: Oct 2002
Posts: 3,652
Likes: 6
From: Lansdale, PA
Originally Posted by SpiderX
What is he corretion factor for the old gearbox vs the new when testing from 3500 - 6000
So my car would be about 1/2 second faster with the new gearing.
BTW, my ambient temp was 32 * F and altitude was 400 ft.
Thread Starter
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OVERDRIVE
Joined: May 2003
Posts: 7,926
Likes: 40
From: Greensboro, NC
Originally Posted by andy@ross-tech.com
I did a pair of 3500-6000 runs in 3rd gear during lunch. It was a level surface, and I did one run in each direction. I datalogged RPM and got:
Run 1: 5.467 s
Run 2: 5.410 s
Run 1: 5.467 s
Run 2: 5.410 s
6th Gear
Joined: Oct 2002
Posts: 3,652
Likes: 6
From: Lansdale, PA
Originally Posted by MSFITOY
Did you start from a steady 3500rpm or accelerated past it from lower rpm? If you held at 3500rpm, how did you get the rpm to steady before the run? Steady foot or cruise control?
Thread Starter
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OVERDRIVE
Joined: May 2003
Posts: 7,926
Likes: 40
From: Greensboro, NC
Originally Posted by andy@ross-tech.com
I accelerated past it from a lower RPM. It's not possible to maintain exactly 3500 rpm no matter how sensitive your foot or cruise control is.
6th Gear
Joined: Oct 2002
Posts: 3,652
Likes: 6
From: Lansdale, PA
Originally Posted by MSFITOY
That's what I gathered from your quick numbers...you've added momentum
Using actual RPM as opposed to perceived RPM as illustrated on the not-too-accurate tach.
Using actual timestamps as opposed to using a stopwatch operated by none-too-accurate fingers.
Yep
Originally Posted by MSFITOY
I'll have look and see if my Gtech can do timing between speeds...
Matt
Thread Starter
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OVERDRIVE
Joined: May 2003
Posts: 7,926
Likes: 40
From: Greensboro, NC
Originally Posted by Dr Obnxs
Do a run from lower to higher. Import it into the sW, use the cursors and set them at 3500 and 6k, et voila, time from speed to speed (or RPM to RPM).
Matt
Matt
Sure...
Originally Posted by MSFITOY
Could you stretch that explanation out a little Matt? I haven't seen my instruction book in a while but this sounds interesting
If that doesn't cover it, read up, my man!
Hope that helps...
Matt
Thread Starter
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OVERDRIVE
Joined: May 2003
Posts: 7,926
Likes: 40
From: Greensboro, NC
Originally Posted by Dr Obnxs
When you make a run, keep in in thirg gear or whatever is being tested here when you do a HP run (stage, go in first shift early, second, shift early, third and rev all the way to the top). When you load the run into the desktop/laptop computer, you can go to the speed vs RPM display (or speed vs time, I'm working from memory) and use the cursors to mark two places on the curve. On the tables over on the left of the SW, it will show the time between the cursors. You may be able to do this on the unit as well, but I'm not too sure.
If that doesn't cover it, read up, my man!
Hope that helps...
Matt
If that doesn't cover it, read up, my man!
Hope that helps...
Matt
Now if the snow would go away
5th Gear
Joined: Oct 2004
Posts: 1,005
Likes: 157
From: Northern Jersey
ok so i was out cruising this evening and i had my friend use a stop watch to work out the 3500-6000 times.
It was about 30 degrees F on a flat patch of 287N near Morristown. My friend was 200 pounds I do not know the altitude or pressure
But on three runs i averaged 6.3 seconds. I used cruise control on what was the center between 3 and 4, but it certainly isnt exact.
It was about 30 degrees F on a flat patch of 287N near Morristown. My friend was 200 pounds I do not know the altitude or pressure
But on three runs i averaged 6.3 seconds. I used cruise control on what was the center between 3 and 4, but it certainly isnt exact.
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