Editing Engine tuning (section)

==Definitions==

===Overhaul===
An overhauled engine is one that has been removed, disassembled, cleaned, inspected, repaired as necessary and tested using [[factory service manual]] approved procedures. The procedure generally involves [[Honing (metalworking)|honing]], new [[piston ring]]s, [[Bearing (mechanical)|bearings]], [[gasket]]s and oil seals. The engine may be overhauled to 'new limits' or 'service limits', or a combination of the two using used parts, new [[original equipment manufacturer]] (OEM) parts, or new [[Aftermarket (automotive)|aftermarket]] parts. The engine's previous operating history is maintained and it is returned with zero hours since major overhaul.

Aftermarket part manufacturers are often the OEM part-suppliers to major engine manufacturers.<ref name="mattituck1">{{cite web|last=MR|first=MR|title=Engine Overhaul Terminology and Standards|url=http://www.mattituck.com/articles/ohterms.htm|publisher=Mattituck Services, Inc|access-date=20 August 2011}}</ref>

A "top overhaul" is composed of the replacement of components inside the cylinder head without removing the engine from the vehicle, such as valve and rocker arm replacement. It may include a "[[valve job]]". A "major overhaul" is composed of the whole engine assembly, which requires the engine to be removed from the vehicle and transferred to an engine stand. A major overhaul costs more than a top overhaul.

"New limits" are the factory service manual's approved fits and tolerances to which a new engine is manufactured. This may be accomplished by using "standard" or approved "undersized" and "oversized" tolerances. "Service limits" are the factory service manual's allowable wear fits and tolerances that a new-limits part may deteriorate to and still be a usable component. This may also be accomplished using "standard" and approved "undersized" and "oversized" tolerances.<ref name="mattituck1"/>

===Remanufactured===
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[[Remanufacturing|Remanufactured]] engines are used engines that have been rebuilt to something approximating their manufacturers’ specifications.<ref>{{Cite web|url=https://www.jasperengines.com/remanufactured-engines-faq|title=Remanufactured Gas Engine FAQs {{!}} Jasper Engines|website=www.jasperengines.com|access-date=2019-04-29}}</ref>

A combination of new and used parts are used, with st least the [[cylinder block]] being recycled, typically after having been degreased and steam-cleaned, its coolant passages and oil galleries and passages cleaned, and inspected for cracks and other flaws. High-quality rebuilds will include cylinder honing and typically adjust for standard wear by installing as necessary marginally larger bearings, rings, and other similar wear-prone components, new valve springs and guides, lapping valve seats, and otherwise bringing an engine reasonably close to manufacturer specifications. Better yet remanufacturing may see new pistons and the line-boring of worn crankshaft and camshaft bores to permit larger bushings to be installed.

===Blueprinting===
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[[Blueprint]]ing an engine means to build it to exact design specifications, limits and tolerances created by its OEM engineers.

In spite of that definition, the term is often colloquially used for pursuing better-than-factory tolerances and performance, possibly with custom specifications (as for racing). 

Common goals include engine re-manufacturing to achieve the rated power for its manufacturer's design, and rebuilding an engine to optimize its performance by adhering to or exceeding exacting manufacturer specifications. Blueprinted components allow for a more exact [[Engine balance|balancing of reciprocating parts]] and rotating assemblies so less power is lost through excessive engine vibrations and other mechanical inefficiencies.

When feasible, as with a factory-sponsored race team, blueprinting is performed on components removed from the production line before normal balancing and finishing. Over-machined, under-cast, and deficiently manufactured parts are rejected, and only those either exactly meeting specifications or allowing removal of excess material are selected.  Aftermarket and private parties must work with  what they have or seek suitable replacements that can be brought to spec, following the same guidelines.