TB993tt

Had a bit of a relevation today - the stock speedo is wayyyy out to the point of the 60-130mph speedo runs being pretty meaningless.
The AX22 GPS based device which I got (thanks to Guy R and LAT) highlights how innacurate the speedo is.

Since I went 2WD and got the weight down, the car has felt ballistic and I've really being looking forward to verifying the feeling with numbers:

I measured using a stopwatch and the speedo 60-130mph it came out at 6.8s

Using the AX22 it is 7.85s

For the run, the actual weight was ~1450kg/3198lbs and ambient was 11degC/~52degF

The run is below, sorry for the size, I had to scan it. I need Guy to tell me how to do the copy paste thing with the original graph.
BTW how cr@p are my ~0.5s gear changes



My 100-200kph time came out at around 6.7s

These numbers, unlike the speedo ones I believe are comparable with the magazine tests.
Here are some 100-200kph's
CGT 6.9s
Enzo 6.7s
Zonda (550hp) 7.4s
SLR 7.5s
McLaren F1 6s
Veyron 4.8s

These devices are about $1K and for me soooo more valid than chassis dynos. Any takers

K24madness

Find me a local NorCal guy that has one I can borrow and I would be happy to give you some times. Words can't describe how strong my car is running at the moment. Look forward to compairing it to others.

Jean

Very interesting findings TB. I could be driving a Beetle and thinking I am fast with my video timing
What is even more surprising is that these numbers put you faster than Guy's GT2 beast with 600+HP and similar weight!?

I am in for buying one, I like its simplicity. I have been trying to figure out the installation of My MXL datalogger for 2 weeks now, after installing most of the sensors with great pain, and ditching about $3,000 in parts and shipping, my laptop does not communicate with it

I will put it for sale very soon with all the sensors I bought, someone will make a hell of a bargain.

A couple of years back there was a thread on the 964 forum (I think) where the guys were lending and shipping to each other the same G-Tech device, interesting idea, provided everyone keeps track of it. K24 Madness, I was thinking you guys in California might be able to do sth like this. I just read that rmrmrd (sp) has one.

TB993tt

The weight of GT2s usually comes out around 1460kg, so with 2 people in the car (that is how Guy did that run I believe) and the fact that Guy claims to be well endowed in that department the GT2 could easily be running at 1635kg/3604lbs
To compare the power to weight ratios:
620hp 1635kg GT2 = 385 bhp/tonne
541hp 1450kg 993tt = 380bhp/tonne
So things look about right

Jean

I see.

So how does the AX22 run compare to your AP22 TB? Will you be doing a test with your old device with the exact same calibration as before? That would be interesting as you will find out the weight factor and its impact, and also the variance between both units.

K24madness

Jean,

Thanks for the AX22 lead. Given we are a small community I can't see why we could not share with local guys. I will PM him now.

TB993tt

AP22 was traded in - they give you £100 for it
You can see the difference immediately, when you stick it on continuos it reads the GPS speed very accurately (hence why you can see how cr@p the speedo is) - so it is obvious how it can be leagues ahead of the AP22 which relied only on accelerometer.

Woodster

It looks like the only way to do this is AX22. next summer I will borrow
LAT's (He may leave his RUF in Germany for the summer anyway)AX22
and run my 996TT with PSI 480 kit and my "little old worn out" k-16's.
This will be my "baseline" for future mods. Hopefully I can get my
buddy with the 993TT and Kevin's turbos ect. to do it with me.
Now, someone please get one of these units to K-24 before he goes
MAD with his new mods...

K24madness

Woodster

Why don't you vouch for me and ask LAT to loan me his. I can get several local 993tt's running the garrett ball bearing turbos. There are also some local 996 + GT2's running them as well. They will be going in my car once I drop the motor and do internals.

K24madness

TB,

I can't pass up on the cheap shot. For all of the **** you have given people about chassis dynos being inaccurate and how the 60-130 runs are the only way to judge performance. We now find that the past 60-130 runs have had several flaws rendering all of the past data useless.

Hopefully you english sense of humor can see the irony of this.

TB993tt

Bill S did a particularly fast run by not having to change into 5th gear and using 7200rpm limit in 4th
On my run, I ran it pretty close to 7000rpm, say 6800rpm to be conservative and the AX22 GPS said the speed at the gearchange was 116.8mph.

This means that to hit 130mph in 4th one would have to rev to 7600rpm - the 7200rpm would be about 124mph.

speedos eh.....

TB993tt

I get the irony of the 60-130mph runs we have been attemting being flawed. They were far from "useless". The methodolgy Bill S suggested which we were using ie videoing the speedo and then timing it is repeatable amongst 993tts and WOULD give a good basis for comparison.
We never saw anything from you, just hyperbole, so you could not partake in the comparison, just the chassis dyno stuff which IS "useless"

It is when one wants to compare to magazine or manufacturer numbers which tend to be done very accurately that the speedo method falls down.

K24madness

I have used the dyno as a tuning tool. It has shown its value in evaluating the changes made have resulted in improved power. You consider that useless??

My system is simple. I started here at XXX HP and now I have achived XXX HP

Never intended it to be used to compair to others. But since you insist on using that way then we may as well admit that your "60-130" standard was no better for that purpose due to the many variables of measurement.

You have not seen your 60-130 times yet because I have not quite finished my project. Guess even then the results won't mean much since all of the other "60-130" data is skewed by your own admission.

TB993tt

I'll try and make it simple for you - video your speedo doing 60-130mph on a FLAT road then time the sweep of the needle between these speeds and you CAN use it to compare with the other 993tts who have done this - it is a GOOD comparison OK ?

Yes your chassis dyno numbers mean very little unless they replicate proper road load like conditions - but they make you happy so enjoy

You say you are not finished yet "words can't describe how its running" so share your acceleration numbers, time it yourself show yourself the power is real - it'll tell you more than your chassis dyno

Some of us like to get definitive answers to these questions and the AX22 is a way forward - its only been available for 12 months or so.

K24madness

Yes the 60-130 compairision is somewhat valid when compaired to the same car measured in the same way. There is still speedo accuracy that comes into question. We also know that not all measurements were taken this way. You also want to compair these 60-130 times to other manufactures published times. This is NOT a valid compairsion.

Your original post states the inaccuracy of the tests.

Stop watch and speedo measurements are a joke.

You are on the rite track with the AX22. Now concentrate on getting them in the hands of others and you will have a accurate data base to work from.

If I can get my hands on the AX22 I would be happy to compair my car in its current form.

PS I don't to show myself the power is real. I know it is.