Since I'm on a holding pattern for the transmission I've decided to play around with making a sheet metal intake for the car. Playing with PipeMax, it looks like a 3rd harmonic runner should be about 10", depending on how many rpm the engine is going to be spinning, but 12" seemed like a good middle of the road number. Doing some math, from the throat behind the valve to the where the intake flange bolts to had a taper of 6º, so I just propagated that out 10" out from the flange, calculated out the area using the same height to width ratio of .875 so the ports at the end should be about the same dimension, just bigger.
So I started by making a wooden form of the port from a chunk of 4x4. I drew out the area on either end, lined across the sides for the taper then took progressively closer cuts with a sawzall. I was going to get it close and use my belt sander, but after wasting at least 2 hours looking for the damn sander I gave up and continued making closer cuts with the sawzall and then got the idea to stick a paint stripper disc on my 4.5" grinder and that did a pretty good job of removing material slowly and smoothing out the sawzall cuts. I made it a bit smaller than needed for wiggle room to account for the size of the metal.
I used a blue shop towel wrapped around the piece of wood and trimming it to size to make a pattern to cut the metal by since the taper wouldn't be a perfect rectangle.
Then using a series of C-Clamps and vice grips to hold the metal in place on block of wood while I used my work bench to wrap the metal around the block of wood. Some light massaging with a rubber hammer was involved and I managed to even get the seam to be on the bottom of the runner with a light overlap. I then gave it a quick tack weld to hold it together and knocked the wood out the end.
Some tapping and it slide right into the port.
Not overly fancy.
From the flange side.
And will it fit on the engine?? It's about an inch or so long here as the plenum end still needs to be cut and squared up. I'm contemplating ways to get a rounder bell shape on that end, but not 100% sure it's going to happen.
It's pretty thin gauge metal, so I intend to use small lengths of angle iron along the bottom of the runners to support the weight of the eventual plenum. I am going to get steel injector bungs and they will be tacked to the flange to hold them solidly in place.
