There are several valid reasons for the replacement JDM engines in the United States Domestic Market and other worldwide market engines. However, the major reason is that in Japan, all vehicles should pass a car inspection, known as Shaken. This inspection will only determine, whether the car is still appropriate to be driven on the Japanese roads. Shaken can be extremely costly and often it will drive the value of the vehicles to zero. The older a vehicle gets, meeting the Shaken standards may involve thousands of yen.

Traditionally, the Japanese vehicle owners do not like to get concerned with the auto repairs of their vehicles. This is because auto mechanics charge their customers with a hefty repair charge for simple repairs, particularly to meet the standards set by Shaken. If your car fails in the Shaken inspection, then it will be considered illegal to drive on the Japanese roads.

Another reason for replacement JDM engines for your original engine is that most of these engines are the low mileage motors, usually, less than 45,000 to 65,000 miles. Furthermore, they have an immense deal of operational life left in them. Although most JDM engines are internally identical to that of the United States versions, some motors, which can be used in the United States, are smaller in their displacement, so they may need some changes in their displacement to meet the Shaken standards.

Usually, the Japanese Domestic Market engines have low mileage when compared to those in the United States. Wide open areas of road to speed up and restricted traffic when compared to the island of Japan, not to mention the traditions of the vehicle in America, offering the Japanese motors a much less demanding situation. Alternatively, there can be JDM engines that have inhabited the heart of the Tokyo City and they have been inactive along the crowded roadways, adding low mileage, but accomplishing so in a very unfriendly environment of the city.