Bill S.

I think they got those from me. The 7.0 was taken from an early magazine test and is probably not right...

"The Enzo's major straight-line numbers—0 to 60 mph in a flabbergasting 3.3 seconds, a quarter-mile of 11.2 at 136 mph—aren't as ironclad as we'd like. The acceleration runs on Fiorano's straightaway were slightly downhill and too short to get a true quarter-mile, so our 1320-foot time is a mathematical plot from the last solid data point at 120 mph and 954 feet."

JBL930

I found an interesting link posted on Pelican, i know nothing can replicate doing the test on the road with a properly calibrated device like the VBox or AX22, but it has given me quite accurate figures and thought i'd share.

My dyno figures are of the chassis variety, so open to the obvious debate, but bare with me

Data i put into the tool, remember i have a 930 with a stock 4 speed box and a 993tt engine.

Weight 3000lbs
Drag Coefficient 0.4 (data from here http://www.getcarspecs.com/porsche/1...sche-930-turbo )
Frontal area 15ft (guess)

Torque taken from my dyno sheet

3000 - 327
3500 - 433
4000 - 490
4500 - 528
5000 - 520
5500 - 471
6000 - 431
6500 - 401
7000 - 360

Stock 4 speed gearing is:

2.25
1.304
.892
.625
4.22 final drive

245/45/16 tires

190lb driver
600ms shift time.

I get a 60-120mph of 6 seconds on the AX22 with stock wheels, and i hit a top speed of a little over 187mph at Bruntingthorpe






The tool gave me this info after i input the data above and plotted my torque curve into the tool, the torque numbers need to be flywheel.





And my chassis dyno sheet for reference





I now have bigger wheels with 285/40/17's and it gave me this, a theoretical 205mph. It has hurt the 60-120 though which is what i expected as it doesn't seam to pick up quite as quick. Will do some runs soon and see





It's just a bit of fun, thought it may entertain you guys if you're bored!? Obviously you need quite a bit of data from your cars, gearing, dyno graphs etc etc, would be interesting to see if it's acurate for anyone else?

JBL930

Sorry, the link is here http://vlsicad.ucsd.edu/~sharma/Potpourri/perf_est.html

Jean

Jon

Nice find

These models can work very well and simulate performance acceleration quite accurately as long as they are fine tuned for specific cars. I have developped a similar model that I have been using for a couple of years and been validating and fine tuning the formulas and other friction coefficients, aerodynamics, etc.. based on actual datalogger data and interpolation. I use factory stock cars for the testing to ensure that my numbers are not far off.

The other advantage is that once you have fine-tuned this tool, you can easily spot dyno optimism for any Porsche car, by plotting the Dyno numbers on the tool in 500rpm increments and see what the performance figures are, then compare to the datalogged run.. Cars like Toby's were extremely accurate, which tells you that RS Tuning really has spot on readings for their dyno.

Another use is a simulation of what would be your times once you change weight, coefficient of friction of tires (this model does not), air density, engine numbers, tire sizes , gear ratios etc..

An intersting finding was th eimpact of downforce on high speed acceleration.. You simulate a CGT run with the factory data, and up to 140-150mph or so the model is spot on, then the higher your speed goes, the more inaccurate the simulation becomes and the slower the real run CGT is vs. what it should be, all of this while using the correct drag numbers... Clearly the impact of downforce (not drag) on the CGT..

Not sure this is clear, but I would be happy to elaborate. My model is obviously not as nicely presented but it gives you by far more data, for example acceleration within gears from any speed to any speed in any gear etc.. Fun..when you have time!!

JBL930

I understand what you are saying i think. If this tool had an option to input downforce at a particular speed, say 50kgs of downforce at 120mph or whatever, it would calculate the effect, and adjust the result. How would you find out the data in the first place without a wind tunnel?
I suppose if it was clever enough you could have an option to input acceleration data from your AX22 and it would give you the drag and downforce of the car!

This model is quite crude i suppose, it's clever though! It would be great if it gave predictions for any speed, 0-300kph for instance. I will be doing this test soon, do you have a prediction for me Jean?
Do you have any plans of putting your model in a usable format for the masses?

Jean

Jon

If you have any acceleration data for your car on datalogger with the current configuration, send me the raw data and I can draw the acceleration graphs of what your car is supposed to do during a 0-300kph and any speeds in between including distance required, Gs, etc.. Predicitions for high speed runs are impacted greatly by several things such as wind during that day or engine heat soak for instance, but assuming the engine keeps its power as it should and wind is not important, you will get a pretty good picture yes. Also different tires, shift points and gears can be optimized.

Downforce only has an important impact on cars like the CGT or the 997GT2, for the rest, it will have an effect but not dramatic.

I use this model for my own fun, if I ever get some time to bring a consultant to make it nicer and easy to use I might upload it somewhere, it has saved data on several Porsche cars including many on this board.

JBL930

I only have runs with the stock wheels with 245/45/16's but will send it anyway, new rear tires are 285/40/17's. I also have a run up to 300kph with the old wheels but not from 0, and i wasn't pushing the car at all through the gears as the goal was just to see top speed, not acceleration data. The next time out i will start from 0, and take it to near the red line with every gear change I'll email you both files now, cheers Jean

Jean

Jon
Here is the data I got from my model. It seems that your engine is heat soaking, based on the V Max run that you sent me, initially you had more power and torque than later during the run, all of this adjusted for drag etc obviously. Good tunes show consistent HP and torque all the way to 300kph. Your dyno figures seem to be only a bit optimistic, the torque curve comes earlier in real life (based on the model), most likely because of lack of enough dyno load.

Your HP and torque numbers are shown on the coloured square bottom LHS, sub-500bhp. My calculated acceleration numbers here are as close to the datalogged runs that you sent me as possible, obviously they cannot be exactly the same due to shift points (model shifts at best rpm), as they are based on a theroretical engine dyno sheet that I created to match this acceleration to your car.

I am posting a picture of the data I got with 17" and another with your current setup. Not much difference on a 0-300kph run, about 4tenths faster with smaller tires. Max speed achievable with each is shown on the model, but you could only reach it if distance was not an issue.

Let me know here on on email if you have any questions. Cheers

With 17":


With 16", everything else the same.

JBL930

Wow Jean, you weren't joking when you said yours was a bit more involved!! I'm hoping to have the car up at Bruntingthorpe in the next few weeks, will do some runs then and log everything, i will also start from 0 and take it right up to near the red line on every gear change, unlike the 300kph run i sent you which was very lazy!
I need to think about creating a seal between the intercooler and the tail, and also a way of getting cold air into the airbox, i'm sure this will help with the heat soak.
Car will be totally different when i get the RS-K24's and the 520ps ECU, neither of my current ECU's are optimal so i don't doubt it's loosing performance, just have to wait until the new year. Thanks for crunching the numbers, i've printed them off

Jean

JBL there is much more info and graphs obtainable from the model (distance, Gs, traction levels, optimum shift levels,etc..) Just send me your questions or scenarios (gearing, weight, engine config...) by email and I will send you back the results.

Basal Skull

Jean I think your model is pretty spectacular. Now I understand what you do with/to look at the data that's been presented in these forums! I like models/equations/stats and have come up with some interesting things for predicting outcomes for the tumors I operate on and I know how much work is required to work out/refine even simple mathematical predictors. Great once it's done but lots of work.

All the variables/information are discrete numbers in your model but there must be some measurement error and some confidence interval/standard deviation that can come out of the numbers?

Ryojo

JBL930

Got my car back last week after the engine rebuild, drove 2 hours to a dyno i hadn't used before, within 15 minutes of arriving the car was misfiring badly, put it on the rollers anyway but it wasn't playing ball. Drove it back to Northways and it turns out the coil was shot! I picked it back up on Wednesday and as it was the first dry day today i thought would do a run.
I was expecting around 8 seconds, but i actually got my best time ever, chuffed to bits!! Car feels really good with the new stiffer rear springs too, it still puts my heart in my mouth

malcolmd

Having purchased a Performance Box, I can now post a 100-200 time for my UMW Stage 2 setup.
Currently the car weighs 1420kg plus driver and fuel 100kg = 1520kg
Setup is as detailed in the signature. Ambient was 24C.
Probably a little advantaged by the initial fall in altitude of 2m with net loss of 1m over the entire run. The road was rather bumpy in the 4th gear run, accounting for the minor fluctuations in the the long Gs as well as the speed plot. Its hard to find a road around here to do this as all the "good" roads would likely see you loose the licence! Time was 8.76s - being fairly similar to other posts for this setup. Achieved the 200 in 4th by virtue of slightly taller tyres P Zero Corsa 295/35/18s permitting a one gear change run.

TurboM3

very nice

something happened at over 160 kmh where the red graph's slope decreases.

Gibbo

Hi there

Thread revival!

Was wondering does anyone have times for stock 997 C2S and/or C4S?