This is REALLY off-topic now, but I'm gonna send my reply to the list anyway, since the thread seems to be pretty popular. Note that I've added [OT] to the subject line. John Pearson wrote: > > > 1. Wheelspin on launch is NECESSARY for the fastest times > > > > > > 2. The deformation of the rear tires under heavy > > > acceleration changes their circumference (in the wrong > > > direction), so the traction-control system will > > > incorrectly see slippage when there is none > > > > > > 3. Maximum traction isn't developed with no wheelspin, > > > anyway; the most acceleration is developed when the tires > > > are slightly slipping > > This is so cool. I can't believe it, but I am learning more on the > piclist than I do on Car techboards. > > I am leary about the claim that tires offer more traction when > slipping, but have been in many circumstances when I get poor 60 foot > times when the track is sticky and my tires hook. And real good short > times when my tires "chirp, chirp, chirp"! So I am going to take this > seriously. John: What you're seeing is the effect of the FIRST thing I mentioned, not the third. While it's true that pneumatic rubber tires on asphalt reach peak traction when they're slipping a little, you're unlikely to see that effect (since your car has relatively-modest power) except for a brief moment right after launch or under hard braking/cornering (which isn't real applicable to drag racing). > The thing I wanted to say though, is that I am using street radials. > The reason they are so poor with acceleration is that they don't > deform. They are like accelerating with wooden wheels. They don't "wind up" like drag slicks (your car wouldn't wind drag slicks anyway), and they don't "squish" as much as a drag slick would, but they DO squish enough that any wheelspeed-based traction-control system would have to account for the change. It sounds as though you're relatively new to the whole racing thing. It's great to see that you're so enthusiastic about doing your own engine modifications -- that's rare these days, when so many people just want to buy mail-order "performance" parts -- but at this early stage of the game, the most cost-effective way to improve your times is probably through improving your own driving. Take a class if one's available at your local strip, talk to experienced racers, practice practice practice... That sort of thing. Computer-controlled spark timing is one of those things that adds just a TINY bit of performance to a car that's already running near-optimally; you're likely to see MUCH more dramatic gains by working on your technique. If it helps, ask yourself before buying any parts, "If John Force were driving my car as-is, could he get substantially better times than me?" As long as the answer's yes, you don't need those parts. Just a bit of unsolicited advice; feel free to ignore it. -Andy (whose last run in his dead-stock daily driver, on street tires, was 13.5xx at 108 MPH) === Andrew Warren - fastfwd@ix.netcom.com === Fast Forward Engineering - San Diego, California === http://www.geocities.com/SiliconValley/2499