And of course, 'tuning' of a cars' engine, to improve efficiency, economy and power output is a VERY big subject, and far more than I can go into here, other than stating that the four-stroke internal-combustion engine is quite simply a pump, which works on the principles of Suck, Squash, Bang and Blow - any improvement you make to these areas is considered 'tuning'.In the most general terms, Suck is the induction part of the cycle, where you can duct more cold air into the engine, increase the size and/or number of inlet valves, lift those valves higher with a more aggressive camshaft, port the head for a clearer path through it, mix that air with more atomised fuel from the injectors, perhaps being forced in by a turbo or supercharger... Squash relates to the compression of the fuel&air mixture, and if you increase the Compression-Ratio you will get a bigger Bang - as you will if you use a better TIMED, more energetic SPARK, which you may use two spark-plugs to provide. BLOW relates to the expulsion of burnt gases from the engine, via the exhaust valves - make the valves larger, lift them higher with a modified camshaft, port the head for a faster path out, and use a non-restrictive exhaust system, and you have done all you can.
One would tune a string for a musical instrument by winding it tighter to raise the pitch, or looser to lower the pitch.
One would tune a frequency for a radio by varying the L-C network in the detecting stage. Usually a variable capacitor was used.
If it is PID tuning that you are referring to, then study the methods given by Johnson in his book on process control instrumentation
What are you wanting to tune?
