Hittar ingen bättre bild just nu än denna från Vialle LPI (LPG insprutning) manualen.
The intermediate adapter When there is sufficient space available, we can make use of an intermediate adapter. In this event, an adapter is mounted at the location of the petrol injector. This injector is then replaced in the adapter, as well as the LPG injector. In principle, with this method there is no need to adapt the manifold. The injector discharge pipe is integrated in the adapter.
Där finns förutom dessa även andra försla på hur man kan få in en extra uppsättning injektorer.