I'm not sure... but I think I just got motion sickness. Someone let me off this ride, LOL! :)

Okay Scott and Peter... it's on. ;)

Peter

I haven't, and don't think I ever will, in fact I am looking at ways to tame down my own car to be able to keep it going straight at the race track!

Scott,

Thanks for the info, makes for a very interesting and visual point of view, and the comparison using car lengths instead of feet is excellent.

I know how much time these analysis take and I do not want to waste more of your time being away from the family. I was in fact looking at distance vs. time rather than distance vs. speed. The results will not be very different but you can visualize better for example after 1 second where each car would be, after 2, 3 seconds, etc..

Feel free to email me an excel extract of speed, distance and time for these three cars and I can send you back some graphs if you wish that you could post.

Thanks

the driftbox plots with that insane Heffner GT are great! Thanks!

In the first post of this thread there is a very long explanation why ET and trap speed of a quarter mile run can differ with different runs and cars.
I would like to try to show you a shorter explained version which put some light from another side:

Why does ET and trap speed of a quarter mile run (or any other distance) differ?
Simple answer is: because the process/the distribution of acceleration (increase of speed per time) is changing over time and distance.

this is very similar to a turbo and a n/a engine which have the same (max) power, but completely different distribution of power over the revs (->torque).

If you consider cars that have a constant(!) acceleration, it would always have corresponding ET and Trap speed.
This is not true if you only take an average of your acceleration.

Here are two examples in terms of raw numbers, which are perfect to explain, because lower ET has also lower speed which seems strange at the first glance:

Car1 11,0@123 and
Car2 12,8@140.

Both cars have an average of 0,5g acceleration but VERY different times and speed. As you might know from experience, the 11,0 is a car that speeds up fast but has not enough power at the end, and the 12,8 has more power at the top end and probably a bad start.
This two examples were made within excel to demonstrate the influence of changing acceleration. It can be easily done with performance box software also, but here we eliminate errors at the start and during shifting.

Car1 starts well with 1g and is losing 0,09g every 0.1 sec and has no acceleration left at 404meter (=quarter mile).
Car2 is doing 0,5g all the time (has enough power to keep 0,5g at the end)

In easy words you can say: it’s more important to accelerate perfect at the beginning rather than at the end to reach good E/T. this is simply because “you do not need any further increase in speed to make you way, if you are already fast”. Look at the top fueler’s ET that blow their engine after some 60 feet ;)

I did not mention any shift point and pauses, but they are more important in the first half of the quarter mile.
It’s not a secret that great times result from very good grip (drag tires, AWD) and maybe skipping the first gear and use a lot of clutch.
And therefore it is very important to have a light car. There are light VW beetles with 700kg and only 230 rwhp that do times in mid to low 10’s, but they would have very poor standing mile times…

see attached both runs in a diagramm over distance!

Scott,

Really, really cool and interesting info!

Aaron, How the hell did you get ahold of that data? (I saw the cars run and the Ford
GT was/is awesome!)

RS38: thanks for finally adding to the discussion

Jean: get back to your Vacation and hopefully we can send you more info!!!

Great thread!

MK

I got the raw dbn file from Jason Heffner as well as from the owner of the car.

Aaron

Hi,

Are any of you boys using the higher end VBOX product? I started off with the VBOX Mini and now use the top line VBOX3 100Hz unit.

I test/tune quite a few cars, one of particular interest would go well, its pushing (500+rwhp as recorded on my equipment) and weight comes in at 1150kg... it out accelerates a Pagani Zonda hilarious

Here is a link to my gear on the VBOX tests.

Great thread BTW !

Peter

http://www.riceracing.com.au/

http://www.riceracing.com.au/fd3s-tuning.htm

vbox mini has the same hardware as drift- and performance box. But these 100hz devices are awesome. especially used together with differntial GPS it is freightening how accurate they are. there are a lot of nice video demonstrating this on the co.uk web site.

do you have a chance to compare vbox mini directly with vbox3??

Hi yes on my last tuning trip one of my customers used his own VBOX Mini and I had my VBOX3 hooked up in the same vehicle and it was within 1/10th of a second.

I have a bit of a thread along with links from Race Logic's site comparing the 10Hz low cost option to the reference std VBO3 100Hz unit. This was back before I owned either unit and I was looking into what type of data logger and performance measuring device I should go for... I liked race Logic since I had used their traction control equipment previously and got recommended them by another business.

Have a read if your interested.

http://www.ausrotary.com/viewtopic.p...143457&start=0

Race Logic factory test report

http://www.performancebox.co.uk/down...CHvPB_Test.pdf

^ As I stated above I can personally vouch for the lower spec VBOX to be within the same level of accuracy as in the above report. Not bad at all given my VBO3 is around $25000 worth of equipment :D I loved my basic unit so much I had to get the top spec version, my customers appreciate it almost as much as I do :p

Those test results are very informative. It's amazing how accurate a $500.00 Performance box really is. What an awesome piece of equipment.

Indeed ;) It is the best bits of gear I have in my tuning kit, it is 100% beyond reproach... many of my customers spend big dollars on dyno time only to see that I can make their cars go faster in the real world after tuning with my VBOX equipment (before and after tests, repeated in same way in same location). There is nothing like knowing how fast your car really is versus how fast it should be :D

p.s. keep up the great work, this was one of the threads that made me buy my own VBOX Mini !

Guys,

MBailey sent me a new run that he just ran that beat his last one by a good measure. He ran a 8.14 with 1-shift on a 0.1% decline (almost perfectly flat).

His car keeps getting faster. His last run was a 8.52 and the one before that was a 9.68. Congrats, Mike!

Nice run MBailey. Tell me about the car a little if you can?

Its a 2003 996TT AWD with EVO GT610, headers, Hitachi MAF, billet shift link, EVO DVs, Sachs stage 1 clutch, Fabspeed Gen3, Clubsport ICs, and Odyssey battery. I was running VP MS-103. The temp was 64F, 29.99 in hg, 86% humidity.

Iam hoping with a real cold front I can get below 8s.

Very nice run, MBailey!! If possible, you might look into shedding more weight and see what happens. I bet you get < 7.5 real soon.