4cyl plenum base
This is our new LPS formed 4cyl plenum base to match our formed runners. They have a formed in velocity stack/radius, are made from 1/8" 5052, the outside dimensions are 5" x 15.75", a 2.5" bore inside diameter, and they have 91mm bore centers. Most popular 4cyl engines bore centers fal between 88mm and 94mm so a slight angle on the runners of whatever you are building should get you mated up to this plenum base smoothly.
Happy Building, send us pictures!