I ran even 15 once.... whatever you do make sure no more then 20 psi.
I experimented with just about every parameter there is.
I do a dry burn out just b4- that helps as well. turn off PSM

 

Mark, I just got my new wastegate springs today and hopefully they will be on in short order. I still cannot believe there is more mid range torque to be had with these springs, but we shall see. Any hints or tips , drop me a note

 

did u get the springs preset? did kevin lock up the inner nut so u cant mess up the adjustment? this is very important since both turbos have to works exactly the same.

 

I left at 4750 RPM with stock tyre pressure after a good 1-2 second burnout. I got a 1.7x short time after a few tries using that method. I wasn't skillfull enough to leave at 5000 RPM without getting excess wheelspin.

 

Well, whatever works for you. I personally do not think a 1-2 sec burnout will do much beyond stress the driveline. You cannot heat tires in 1-2 seconds and certainly not stock tires. I believe that a launch that high in the rev range is just eating the clutch because to get a 1.7 60 ft you have to be slipping the clutch otherwise you get wheel hop or wheel spin. At any rate a 1.7 is a great 60 with these cars. Kevin

 

Kevin, a 1-2 second burnout will remove water and debris without reducing grip on street radials. You can't "get heat into" street radials for the purposes of a good launch at a drag strip.

You *want* some wheelspin for an optimal launch. And yes, to get a hard launch on street tyres you need to slip the clutch. That's how drag racing is done!

 

Kenny, have you tried lowering the tire pressures? Stock radials are rock hard at spec inflation.BTW, over the last 20 years I have 200+ passes at the track with various vehicles, I have a good grasp of " how drag racing is done" take care, Kevin

 

Kevin, yeah we experimented with 20 psi to 45 psi on the tyres and 2000 RPM to 5500 RPM on the launch in 250- RPM increments. When I found the sweet spot I covered 4000 to 5000 RM launches in 100 RPM increments (best granularity I could get without a two step!).

I've also tried street radials, drag radial and drag slicks with short, quick and hard burnouts.

I've tried clutch modulation all the way from sidestepping to never letting the clutch all the way out in any gear!

We also video the car on the start line and then examine the runs on slomo playback to see how the car reacts with the different parameters. This gave some very interesting results.

I take the well documented approach to try to get the best performance from each car I've taken to the drag strip over the years. Change one parameter at a time and record the setup and the resulting short time.

With my Porka it was consistently 4750 RPM that got the best short time. My tyre pressure was 40-44 psi. I got worse results when I reduced the tyre pressure below 40 psi.

Obviously every car is different and I know that most posters here don't have stock 996 TTs, but that's what worked for me.

One thing I'm glad to see is more interest in this group about what our cars can do on the drag strip, good to see :-)

 

Not trying to flame or hijack,...I know you know your cars, but one factor at a time experimentation is definately not the best way to optimize the process. You must use factorials to identify significant interactions (e.g., in the equation F=ma, ma is an interaction of mass and acceleration). I'd be happy to set-up some designs for you if you give me the parameters you want to test. Statistics is what I do.

 

I'm always happy to learn something!

For a street car (ie no slipper clutch, no tweaking the tune between passes) the parameters to be altered are:

+ Rear tyre pressure (increments say 0.5 psi)
+ Front tyre pressure (much less important)
+ Raceweight (things like how much fuel is on baord)
+ Launch RPM
+ Rear rubber
+ Burnout
+ Clutch action on launch


The ambient conditions play a big part in the result (but can't be adjusted the other parameters have to be adjusted to suit changes in ambient conditions):

+ Track altitude
+ Track temperature
+ Air temp
+ Barometric pressure
+ Humidity

+ Track performance (available traction on the day)

 

Kenny, Give me 2 levels for each of the parameters in the first list. I'll suggest we just record values for the parameters in the second list(for now).

 

Kenny, what on Earth did you do to your M Coupe to get it in the tens? That time is phenomenal. Can you say "Sleeper" . Kevin

 

+ Rear tyre pressure - Say 0.5 psi increments on a range 10 psi to 18 psi
+ Front tyre pressure - Say fixed at 55 psi
+ Raceweight (things like how much fuel is on board) - Say fixed
+ Launch RPM - Say increments of 250 RPM in range 7000 - 8500 RPM
+ Rear rubber - Say fixed as slicks
+ Burnout - Say fixed as Initial hard burnout on first pass followed by short burnouts each pass thereafter
+ Clutch action on launch - Say fixed at popping clutch on twostep

So for the purposes of a workable system at trackside you'd manipulate tyre pressure and launch RPMs and keep all other factors fixed for that session.

 

Kevin, thanks for the kind words. It's not as much of a sleeper as it used to be now!

I ran 10.7 @ 136 in the previous trim. Currently making some final touches before going out again to reset my best ET!

For anyone interested you can see some of my movies here.

 

Holly Crap Kenny that car looks like it gets a little squirley going down the track! Great Videos!