Wheel speed

[hemidakota]

Hi rooman, I saw a couple of your builds at the march meet. Very nice builds in the top fuel class. The question I have is air pressure vs wheel speed and wheelie bar height. There is quite a  controversial conversation about wheel speed vs wheelie bar topic between quite a few people at the track. I have been told the lower the tire pressure the faster the wheel speed and this weekend I was told I was wrong, I am interested In your input on this topic. maybe I am way out of line but I am talking about a 7.0 to 7.6 fed deal. What is your input on this topic? I have always found lower pressure gets you up on the slick faster but am I wrong? I am by all means not a pro and I would like to be schooled on this topic. Thanks

[rooman]

There is no hard and fast rule regarding how tire pressure relates to wheel speed as every car is different. A lot of the 7.0 guys tend to overtire the car to make sure that it will go down the track in any conditions and adjust from there. We run 6.5 lbs in the Goodyears on Mark Vaught's 7.0 car no matter what and tune the launch with the wheelie bar. If the track is exceptionally tight I will lower the bar a little to keep the car from dead hooking and shaking. With a small block for power we tend to run the car more like a Comp elim deal with just enough tire to get the job done.
 Derek McCustion's current 7.50 car (that he purchased to replace the one that burned to the ground) is not ideal as the motor is too far back and it is a little over tired but we got it to work and stop shaking and wheelstanding by lowering the bar until the tires slipped enough. It went from carrying the front end and shaking violently to running a 7.48 with nothing more than a wheelie bar height adjustment.
 If you pump the tire up until they crown you will get wheel speed but the car is more likely to skate and if you get the pressure too low there is a chance that the tire will wad up and shake.

Roo
ps  Thanks for the comments on Brendan and Dan's cars

[hemidakota]

Thank you for the info Roo. Yes I am not sure which car is the yellow TF car but we were next to it in staging and the attention to detail on that FED is amazing. It is a work of art. Too bad the weather was so crazy but they always seem to get it done. And as always it was a great time.