Ƙarƙashin farantin gadi na injin, wanda kuma aka sani da farantin gadin inji, galibi na'urar kariya ce ta injin da aka keɓe a kusa da ainihin ramin girdar da ke kewayen samfurin da injin ɗin. Manufar tsara shi shine don hana lalacewar injin sakamakon tasirin dutsen da ke fitowa daga saman titi, sannan don hana mamaye ƙasa da najasa a cikin sashin injin yayin aikin tuƙi, wanda ke haifar da gazawar injin. Ta hanyar ainihin filin ajiye motoci 3D zane mai girma uku, don samar da mafi kyawun kariya ga injin, don guje wa tsarin tafiya, saboda abubuwan waje da ke haifar da lalacewar injin, wanda ke haifar da ɓoyayyen ɓoyayyen motar mota, tsawaita rayuwar sabis na engine, tuki babu damuwa!
Ƙananan farantin kariya na injin na'urar kariya ce ta injin da aka kera bisa nau'ikan motoci daban-daban. Zane na farko shine don hana ƙasa rufe injin, wanda ke haifar da ƙarancin zafi na injin. Abu na biyu kuma shi ne don hana injin lalacewa saboda tasirin rashin daidaituwar hanya a kan injin yayin tuki. Ka guje wa karya mota tare da lalacewar injin saboda abubuwan waje yayin tafiya.
