Good to see this being popular. Over at the 993TT board on RL we have been doing this for a while.
One learning is that the margin of error between stopwatch + video and the use of an AX22 is tremendous. The advantage of the AX in this case is that it lets you compare apples to apples in terms of number of shifts performed, wheelspin, etc..It also shows the gearing. For instance a 996 will have an advantage vs the 993 because it goes through the 130mph in 4th instead of 5th. etc..
Looking forward to some data and hoping that guys will post their good and not so good times as well. This is a portable dyno

 

I'll be purchasing one to use with my car once I return to the US (next year).

 

I too love this test.
The only time I did this test in my M5..it did it in 7 seconds flat. 85 degrees outside, and 90 % humidity.

Craig...please, tell us your time. I can't wait to hear your time or BuddyG's time........yeah Buddy, I haven't forgot about my Gtech.........maybe this year I can get it back!

 

Im still dying to see a speedo video from your car.

 

By then we'll all be running 8s Anyways great way to sign off!

 

Acceleration times using BMW's speedometers can't be directly compared to AX22 times.

BMW states that the speedometer on all BMW cars reads high a max of 10% of actual speed + 2.4 mph to compensate for negative tolerances in tire diameters, electronic controls, other factors (Service Bulletin SIB 620296).
So it's 8% fast at best...a little more than 10% at worst. The odometer is correct because it is recorded digitally.

Coming from someone that has owned two M3's, a M5 and a 330...I can assure you this is true.

So...if you are measuring a 60-130 time using a BMW speedometer...you should probably take the car to close to 140 on the speedo to actually ensure you hit 130. But really, the only way to get a truly accurate time is to use a AX22 instead of a speedometer period.

 

Alex, my friend...you'd be sorely mistaken if you think I'm through modifying my car.

 

So then should I start timing at 70 too? Because if what you say is right, then Im not "really" going 60 either.

 

If you start at 60, then you're probably going 56 or so. But since the error increases exponentially... (i.e., 8% at 60 is 4.8 mph...and 8% at 130 is 104. mph)..you have to take that account as you increase your speed.

 

Its funny....You said a while back ago that it took my car 11 seconds to get from 60-130.


It is in that video it takes 7.1. Wierd how you would say 11. I was looking for the video, but I couldn't find it anymore. I think the majority of the people doing these little "self" times really don't care about the GPS'd speed. If my speedo says 60...than Im going to believe im going 60, even if I;m really only going 56. Maybe they should equipt cars with GPS speedo's. So, to you... no speed is legit, or no timed speed is legit...unless its GPS?? Thats quit boring.

 

Nobody here ever claimed any AX22 recorded data. The R&T data isn't even accurate as you can see the Murcielago's times.

Phillym5 no offense but i remember that video and i also timed it. I think it was 40-130 in 11 seconds.

I always time my runs alittle more then the speed im looking for, i dont know about 130 being 140 mph though. I had a pioneer GPS unit on my car and i remember 120 on the speedo was actually showing 123 on the pioneer unit.

Also i dont think the Porsche speedo will be right on the mark either. It is said that Porsche has adopted the European standard which allows the speed to be wrong in a range up to 10% plus 4 kph just like BMW.

 

That would put you on a par with an Enzo. I'm sure your D/A Area 51 M5 is plenty fast, but it would take some serious forced induction to overcome the weight differential and get an M5 even with an Enzo 60-130 mph. Your must have a supercharger??? Do you have one of the 1000 hp M5s doing 9 second 1/4miles? What mods do you have?

Using a speedo to measure 60-130 acceleration is difficult and imprecise. There is simply no denying that an AX22 is FAR more accurate.

Craig

 

As much as i think his car is fast, i sorta doubt the 7 flat number he said for his 60 -130 mph. I dont know what video he is using to base his number. Ive seen one video and it seemed as fast as Scotts Ex M3, i remember the thread about it. In that video his 60-130 would have shown in the upper 8's.I know his car is fully built and its supposed to run plenty psi but ive never heard any real power/numbers on it. In fact that one speedo video was dissapointing to me.

Indeed using a device such as the AX22 will be more accurate, but i doubt seeing a huge difference.

 

From personal experience, it will most likely, *at least* 1-2 second difference, about 200-300ft at those speeds?

 

1-2 second difference is too much. Your talking about 20+mph speedo errors there, and you said at least. I doubt it would that bad.