I am getting ready to build two versions of the hotside out of PVC. One with the headers flipped up - routing the bulk of the pipes above the motor and the other with the headers sitting normal and the piping underneath.
I am sticking with 2.5" pipe off each collector but I have been wondering about one part of the system. I am going to use mandrel bent pipes but where the two 2.5" pipes meet the T4 flange what is my ultimate goal?
I have found flanges that are rounded to fit the pipe without heat stretching the pipes but I would like to just spend the $55 and buy a pre-made section of pipe where they merge to go into a single T4 flange. Do I want my two 2.5" pipes to merge into a single 2.5" pipe at the flange (will this bottleneck the system) or should I step up from two 2.5" inlets to a 2.75" or 3" outlet? It will literally be for 2-3" of the system but I don't want to do all this work to cripple it at the turbo flange.
Examples are given below of the pipe using dual 2.5" inlet to a single 2.5" outlet (outlet size can be changed from 2.5", 2.75" 3" or maybe even bigger with the proper T4 flange for the diameter chosen):
Parallel merge:
http://www.mandrel-bends.com/catalog...mild-1998.html
Splayed merge:
http://www.mandrel-bends.com/catalog...mild-1765.html
Although I can probably make a splayed merge without too much headache, the $55 is worth it to me. Will either of the two merges be a better choice other than a splayed merge giving me more room to weld?
EDIT:
This is for a 383 with a 1.15 AR TC78