I have been wanting to build a top mount manifold for quite some time now for my KA. I finally decided to bet the supplies needed to build one at minimal cost. I chose mild steel over stainless steel because of the price of the materials and I dont have a welder that will weld stainless. Im using a mig wire feed welder to weld this thing up and it should do the job in 2 passes. I made some test welds with 2 passes and took them to work and let our Certified welding inspector ultrasonically test the welds and the welds had great penetration.

Materials Im using:
12 1 1/2" 90 degree but weld els
2 1 1/2" 45 dergree but weld els
5 feet of 1 1/2" schedule 40 mild steel pipe
1 1 1/2" schedule 40 mild steel 4 to 1 merge collector purchased from BMCrace.com for $40. It was cut precisely and the pipes fit together perfectly
1 T3 mild steel flange from BMCrace
1 KA 1/2"thick mild steel flange


Total cost for materials was approx $150. Pipe and elbows were purchased from easter plumbing distributors in Buford GA and the elbows run about $5 each.

Tools used:
Abrasive chop saw
4 1/2" angle grinder
6" bench grinder
tape measure
dial caliper
120 volt mig welder with shielding gas




First thing I tackled was the head flange. It wasnt one the fancy laser cut units so I had to de-bur the ports and had remove some material on the head side to get the flange to line up with the ports in the head. I would recommend getting the flange from BMCrace that is ported to accept the schedule 40 pipe. It makes things much easier.




Next was the collector. It came from BMC race perfectly cut and was an easy fit. I tacked it together and then cut the top where the turbo flange would be mounted




Here is a jug I made to cut the top flat




Then I tacked on the turbo flange. I was told to put bolts in the flange when welding it so the holes dont warp.




Next I started on the runners. The first runner is a PITA and I had several cut and re-tack trial and error fittings but I was patient and got it going. It helps to have someone else to help hold stuff.




And this is as far as I have gotten. I will keep this thing updated as I progress. I will be happy to answer any questions