Originally posted by DansEdgli
Can anyone give me an explanation of using an EF/EL manifold on straight gas and how it works. This would be better than an ED manifold yes?? Ive been told it isnt controlled by the ECU. What is the dual runner design for? Is it a better chioce for a conversion than the ED manifold?
Dan, I don't know much about gas conversions but the split manifold is there to take advantage of the momentum of the incoming air to give a slight "ram" effect and achieve better cylinder filling & thus more low down torque. At lower revs the air is forced to take the long path and in doing so it builds up a bit of speed and momentum. At higher revs/load there is plenty of torque anyway and what you really want to achieve is getting the most air you can into the cylinders as quickly as possible, so the internal butterfly's open the short, more direct path to the valves.
My understanding is that it is controlled by the ECU which also alters ignition timing at the same time.
You could always use the manifold if it better suits a gas conversion and fix it into either the long or short runner position and still use an XF dizzy with manual advance. I think the BA XR6T motor has the manifold in a fixed position as the boost from the turbo far exceeds any gains that might have been made by the momentum of the air alone.
If you use XG engine/gbox mounts it should position it OK in the engine bay but XG had altered radiator/airbox support panels to use EB gear so you will need to sort something out there - shouldn't be too great a headache.