JDM refers to “Japanese domestic market” which is Japan’s home market for vehicles. For importer, it refers to vehicles and parts which are designed with Japanese regulations and to be convenient with Japanese buyers.
Lets focus on why there is a large demand of JDM Engines to swap into cars here . There are several reasons for choosing JDM engines across the world. Though the primary reason is that in Japan , there is a car inspection method known as “Sha-ken” which evaluates whether a car is still suitable for driving on Japanese roads. This inspection is costly and often make the vehicles value to null . So the older a car becomes, fulfilling the standards set by “Sha-ken” gets more expensive .
So Japanese people do not like to do mechanical repairs of their cars. Mechanics can be expensive for usual repairs , mostly to meet the standards set by “Sha-ken” . Failing “Sha-ken” means your car is illegal to drive on Japanese roads .
This issue has created a large industry of recycling related to car parts . The motors have usually low mileage, less than 30-60,000 miles. And they have great deal of operational life left in them. All the JDM engines are internally same almost but there are some engines that have a slightly lesser engine displacement.The changes are to meet the requirements set by Japan for extra taxes. Though it has little affect for typical applications and it may increase the miles per gallon , because of engine sizes.
Many companies will demand that they have the complete control still attached to the motor. However, this demand does not ensure that it is better . During swapping a JDM engine into car, it’s recommended to use the cars original EMS or engine management system and accessories to ensure you stay acquiescent with all emissions requirements. This ensures part availability at your local part store or local repairing shop .