Another 1/4mi track drag racing event. New record for the XKR!
 

Was a good day at a track in Bakersfield California, traction was good
https://cimg1.ibsrv.net/gimg/www.jag...40ff1910c8.jpg
! Had around 12 runs. My 08 4.2 XKR stayed very consistent with half of the runs around 12.6 and 4 runs at 12.59, finally at the very end I managed to pull 12.58 and a 12.55 at 112mph ,and this is with the day heating up and temperatures over 80 degrees , so a very good sign of the capability of the car. Keep in mind my XKR is a convertible so it's 100lb heavier and I'm running stock open differential and on street tires.

I was surprised my car was neck to neck with a 2012 Cts-v rated at 550hp his best run of the day was 12.66

Alex THAT is mightily impressive, much appreciated especially as a 2009 owner of a CTS-V on the forum told me his car would run rings around mine :D :)

Mine is 4.2 �� , 5.0 XkR tuned would easily run away from the Cts-v,
Stock 5.0 would be close

Mine not tuned apparently as standard map, but running smaller upper pulley, K&N's, a larger intercooler and a paramount performance exhaust (rear box deleted).

Tune on these cars has the biggest gain potential. I gained nearly 100hp to the crank , majority of the gains are in the tune programming

Alex what was your dead bone stock time .

At a legit 12.5 this beats a whole load of newer performance vehicles impressive stuff

It would be interesting to see what the RWH is on the 5.0 R motors. Has anyone dyno one and what did you get for numbers.

Steve I don't have bone stock but I have numbers with pulley only. On the same Mustang Dynometer Dyno it was at 369 to the rear wheels. Assuming around 7-10 rwh gain for the pulley , maybe around 359 or so should of been bone stock.


After I installed high flow cats and I developed a tune for our cars using a Dyno. I got 434 rwh in 3rd gear and 426 rwh in 4th gear. This is with safe and modest settings , no crazy timing advance and tuning on crappy CA 91 gas. I know I can still squize out a good amount tuning for race gas.

As far as race tracks. At slower Las Vegas track with pulley only mod I ran best of 13.35 and 105mph trap speed. After aditional mods and tune ran 12.61 and 111mph on the same track and similar conditions. Pretty nice gain!
Both times at Las Vegas track I raced friends Cadillac xlr-v , when I was near stock he ran 13.7 best and we were close,. Time when I was moded he ran 13.8 and we were not really close at all any more

Slight correction to the post above: stock with pulley only Dyno was at 359 not 369

Very impressive Alex!!
I have an 07 XKR -
What do you find is the most effective way to launch the beast to give you the best sprint times?
You probably experiment with different ways to launch the cat?

Thank you Pete ! Yes going from nearly stock 13.3 to 12.5 is a big difference on how the car feels.
As to your question on better take off: for me personally at the track I had best identical 60ft times of 1.88 if I just floored it off the line or if I preloaded by holding the brakes, so can't say one has advantage over the other. Now on the street I think I will give the advantage to holding the brakes to take off. I believe this mode to have less wheel spin and slightly better take off on the street , but can't say it's better at the track yet, more testing on the way.. I don't go much higher than 1100rpm when I preload the brakes, going further gives me wheels spin , but this is with tuned car , lots more torque of the line
I must say ecu Tune has made a big difference compared to stock ,from average of 2.01 to avrg of around 1.92 60ft now