Projects #3 for DEC3_MAR3 from Jason: 2.9L clone manifold.
VW has a 2.8L 12v VR6 motor and in germany they had a 2.9L of the same motor but the manifolds on the 2.9 had a bigger plenum. Since I have done a port and polish on my head and installed cams with a higher lift and enlarged the size of the valves, I decided that I need to incorporate the larger plenum and the best way is to make something similar to the 2.9L manifold.
The manifold in 2.8L form looks like the following image.
The 2.9L encloses the entire bottom section and is hollowed out as the plenum.
I began cutting out the manifold to hollow this section
Almost done
Once I cut the majority out, I then switched to using a flapper disk to smooth the ribs out of the manifold where I cut the supports out.
The material I am using to fill the bottom in is 1/4" 6061 Aluminum plate
I cut out a piece to fit
If you notice, I ground down the sides to make the plate sit flush with the bottom of the manifold. This pretty much placed it as if it was a piece built into the casting.
When welding, I had an issue where the weld kept cracking in only this spot. This was after welding it 3 times...
I solved it by welding the rest of the of the plate and then doing this.
This is the other half of the seam that was cracking.. For some reason this section of it welded fine.
and done. The bottom of this pic where the neck is located wanted to eat up the heat and blow away the plate. I had to sit on the manifold to form a puddle and pull it into the plate so not to burn a hole in the plate.
This was a rushed project and I used a 4 1/2" grinder and PP256 in TIG for this project. This was done with 3/32 tungsten and filler at ~180A
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