Between full-in and full-out there is a transition area in clutch engagement. In normal driving, this transition area is passed through rather quickly in a linier manner.
When you "feather" the clutch, effort is made to engage the clutch with extra effort and time in the transition area. Muscle memory from your thousands of normal launches must be set aside and a "feel" developed so as to not overcome available traction. All while the motor spinning higher than in a normal street launch.
Too quick of an engagement will bog the motor or spin the tires, too slow will burn clutch friction material and result in a slow launch.
With the SVT I've found about 2'-3' of wheel spin leads to my best launches.
04 SVT Focus
"lunch box" muffler delete
15.35 @89mph, 2.29 60', 9.90 1/8 (100% stock)
Last edited by FocusInAlaska; 01-30-2006 at 07:54 PM.