I agree Jim, about 2 or 3 weeks ago, we had .2-.3 TENTHS of a second change from morning time trials to evening racing.....and thats not a mis print....everything in the weathe rhas to be considered....its usually a hundreth ( or so) for each 200-330 of density change, but if you are working from just density altitude alone, it wont get you the right dial.....its very critical on the blown top outlaw car, where we have tons of variables that can change.