i have a e250 van with a 351w e4od built 11-96.obd2 system with EECV
F6UF-12A650-KB computer in it. has 3 o2 sensors 2 before and 1 after converter. the engine has the air tubes in the exaust manifolds (not in the heads) i would like to put headers on it and then run true duel exaust.
i understand it is a pain to run true duels on these trucks because of the inboard midship fuel tank. so i will run 2.5 inch on the outside of the frame rails till after the tank and then run the rest of the pipe between the frame rails and over the rear axel and exit strait out under the bumper. this van will also be converted to 4x4 so i have lots of things to work around. i would like to dump the converter and install a very large H pipe (large enough to accept 2 2.5 inch pipes in and out. in the middle of the h pipe i will install the bung for the after the converter o2 sensor witch i`am sure will have to be a sim.
i`am not sure what headers to use on this truck equal length shortys or long tubes. but i would like them to be stainless just like the rest of the exaust.
i do not have to pass emissions here. and the van came from the factory without a smog pump. has a idler pulley in place of it. truck has factory maf system and sticker on radiator support says federal. (7100 gvw) does this system require back pressure? if so how much? i will do what ever it takes to make this a problem free system. if it requires back pressure i can adjust it with the pipes. i will install a bung in the exaust and install a back pressure guage to tune it. i would like all 8 cyls to run equal. what kind of problems am i going to have in doing this? what can be done to fix the problems? what brand of headers? i want everything heavy duty so i only have to do it once.
what temp is required to make the 3rd o2 sensor sim work correctly. where should the first 2 o2 sensors be installed? i read somewere they should be like 8 or 9 inches from the last cyl on each bank. some ideas would be sweet. it would help me in figuring out what problems i can expect and how to fix them.
i will have access to an exaust shop with all tools and materials to make it happen. this might even get done with the body off the frame (4x4 conversaion) i have 2 of these vans to complete one with 351 and one with 460 both have maf systems but the 351 will get done first. thanks for reading.