I remarked recently at supper with crashbox and ho mathetes that auto mechanics seemed to partake both of art and of science. Art insofar as learned techniques exist, esp. in manipulating the dynamics of fuel and air through available adjustments on a motor; science insofar as the parts of the whole motor exist to each other in a planned order and that order can be grasped.

Now the art aspect of this has mostly to do with tuning, which is undeniably an art, the art of making an engine run well for a specific purpose. And as with all arts, in it one moves away from the theoretical and toward the practical. What works is paramount; not what is supposed to work. It seems to me appropriate to be constantly meditating on the function of this part in the whole while I have my fingers seating nuts and bolts. One views the motor teleologically, as an organism whose design is to, well, run properly. Like any organism, its parts (organs) act toward this end synergistically and any disturbance is rejected. It is better not to take apart a well running motor for this reason, and why part-specific performance upgrades must be approached with such caution. Disturb the part and you disturb the whole.

The science aspect is much easier to deal with, so much easier that most people substitute it for the art. Numbers, settings, volts, psi: it all adds up to a functioning machine. Or not, and when it doesn't clearly some number or setting is wrong. Black and white, find the missing term. Accessible to logic, easy to work out when you have all the data. The laws of physics are laws because they are constant, the variables act according to formulae. A machine acts in accordance with its assembly, its metallurgy, its structural design, all of which may be analyzed.

Science provides the background from which the art may be better understood, and art contributes real-world experience from which the science may be better known. They depend upon each other. Only a proper view of their mutual contribution to engine building will ensure the success of the builder. (A few expensive tools and some good tunes don't hurt, either)