Over the last couple weeks I've been screwing around with the machining on the IR (Individual Runner) intake manifold for my new cylinder heads. As of the last post on this topic I had cut down the sides of the runners to give some clearance between them, so that they would actually bolt on to the special FE Intake Adapter that I am making for these heads. However, as usual things did not exactly go according to plan. When I tried to bolt the runners onto the intake adapter, I ran into interference between the runners. Looking back at the Solidworks model, it became painfully clear that the interference was not just in the vertical plane; that some clearancing of the runners had to be done on the top side and bottom side of each runner, in order for them to fit together on the intake adapter.
This became a huge programming challenge, for a variety of reasons but primarily because of the way the runners were fixtured on the CNC machine, and the complex curves required to machine the clearances. I worked on this for nearly a full week, and along the way came to the conclusion that it would be a lot easier to modify the casting design in certain ways, rather than to try to machine these things with the existing casting design. Here, the 3D printed sand really showed it's worth. It would have been prohibitively expensive to modify, or perhaps scrap, what could have been $20K in tooling to tweak the runner design, but since the first two castings were done with 3D printed sand, I can simply make the changes on the computer and get another batch of 3D printed sand to test the new design. The 3D printed sand isn't cheap, but its a whole lot less expensive than permanent tooling; its a great way to prove out the design before making the tooling investment.
After a week of machining and test fitting, I finally got the runners to bolt up correctly to the intake adapter. There are some mistakes in the machining that make this setup unusable, but at least now I know exactly what needs to be done on the next version of the castings. And the IR intake setup looks really good; here's a couple of pictures:
I think this induction system will make gobs of torque, and I'm looking forward to having it installed on one of my cars.
In the meantime I've been trying to get the 4V intake manifold casting ready to go. Today, after some accelerated work at the foundry and the heat treat plant, I got the first two castings:
Machining on this one starts tomorrow, and with luck I'll get it done in time to bring to the FE Reunion.
