<P> To blueprint an engine means to build it to exact design specs, limits and tolerances created by its oem engineers or other users, such as high performance racing or heavy duty industrial equipment . It is similar to how many other kinds of mechanical machinery are researched, designed and built, such as a submarine or a hydraulic press . </P> <P> Because few have the capability to actually blueprint, and because of the monetary incentive of claiming one has performed the work, many people have come to believe blueprinting only means that all the specifications are double - checked . Serious efforts at blueprinting result in better - than - factory tolerances, possibly with custom specifications appropriate for the application . Common goals include engine re-manufacturing to achieve the rated power for its manufacturer's design (because not all mass - production engines put out the rated power), and to rebuild the engine to make more power from a given design than otherwise intended (because custom engines can often be redesigned to different specifications). Blueprinted components allow for a more exact balancing of reciprocating parts and rotating assemblies so that less power is lost through excessive engine vibrations and other mechanical inefficiencies . </P> <P> Ideally, blueprinting is performed on components removed from the production line before normal balancing and finishing . If finished components are blueprinted, there is the risk that the further removal of material will weaken the component . While it has nothing to do with blueprinting per se, lightening components is generally an advantage provided balance and adequate strength are both maintained, and more precise machining will in general strengthen a part by removing stress points, so in many cases performance tuners are able to work with finished components . </P> <P> For example, an engine manufacturer may list a piston ring end - gap specification of 0.003 to 0.006 inches for general use in a consumer automobile application . For an endurance racing engine which runs at consistently high temperatures, a "blueprinted" specification of 0.0045" to 0.0050" may be desired . For a drag - racing engine which runs only in short bursts, a tighter tolerance of 0.0035 to 0.0040 inch is optimal . Thus "blueprint" can mean tighter or looser clearances, depending on the goal . </P>

How to tune the engine of a car