Maths lesson - same concept, different results Firstly, its not my equation - lets get that clear! The website below works on a similar principle to the one I used earlier, but gave a different (yet similar!) result. ET calculator website variable 1: I know my car weighs 1560kg in racing trim (weighbridge result); I weigh 80kg. Total 1640kg = 3608lb. variable 2: I know from last Friday that my car consistently has a trap speed of 103mph. Using the ET calculator, we now estimate the cars rwhp by inputting the above figures, and get 307.7rwhp. Going to step 2, and inputting the weight and rwhp figures, it tells me I should run approx 13.233. If I quickly put on 20kg, the car + driver now weighs 3652lb; change the weight to that and recalculate, and I should now run 13.287 - so I've lost 0.054sec. Staying with the "I'm bored at work theme", I know that at my last dyno run the car was putting out 207rwkw, which = 277rwhp. So if I now input the actual weight and known rwhp figure, the calculator tells me I should run 13.705 @ 99.45mph. My best time on Friday was 13.62 @ 103.1mph. So the question I now ask is has the Kakimoto chip upped the rwkw slightly as I am consistently running faster mph? I reckon I can find a few tenths by improving launch technique to get the 60' time down - just a damn shame I broke the gearbox on Friday! Whatever - the results show that if you know weight and rwkw, you should be able to get a reasonable approximation of the car's capability using this calculator.