The Intake Manifold

The runner halves, all TIG'd up, ready to be cut

The runner halves, all TIG’d up, ready to be cut

The runners all trimmed up, complete with taper

The runners all trimmed up, complete with taper

Mark HNC'ing up the manifold flange

Mark HNC’ing up the manifold flange

The manifold tacked together

The manifold, tacked together

4g63 Intake Manifold Flange, Completed.

4g63 Intake Manifold Flange, Completed.

The completed RWD intake manifold.

The completed RWD intake manifold.

Mark and I spent the weekend of the fourth of July 2004 making the sheetmetal intake manifold on the rear drive. What’d we start out with? A four foot by eight foot sheet of 4043 (.090″) and a chunk of 6061 for the flanges. I think the 6061 was 1/2″ thick, but I could be wrong. Well, that stuff, and a lot of Mountain Dew Livewire. We’re addicted. That stuff is way too sweet – we call it “nectar”.

The plan went something like this: I was to do all the sheetmetal work and welding, and Mark was to Hessler Numerically Control up the flanges for the manifold. For those of you who don’t know, Mark is a geek – sometimes it’s a little scary. The flange he HNC’d was accurate to a few thousandths. It fit the head perfectly.

So, Mark plotted out the flange, and I got to work
While he was doing that, I started shearing up the sheet aluminum. Then I made up eight runner halves to weld up to make the runners. After breaking the runner halves, I sheared them to length, and welded them up.

So, I did all that, and Mark was about halfway done with the flange.

Next was the plenum. I’ve got a roll, but it sucks ass, so after struggling with it for about an hour, I resorted to using a heavy duty set of gloves, some muscle, and cursing. A vice helped me out a little bit too. The problem was that the plenum is .090″ and the roll I was using is only designed for like 20 gauge steel – (.036″) so it really wasn’t meant for the job. Lesson learned. After finishing that up, I laid out the rest of the pieces for the plenum, trimmed up the runners, the main part of the plenum, and started getting anxious, so I laid out the oil pan on paper.

When Mark completed the flange, it was time to get welding. I welded the runners to the flange first, and then tacked everything else together.

After that, I welded it up

Mark started the throttle body flange while I was doing all that stuff. When I was done welding the plenum to the runners, I cut up some 6061 to tap for bungs on the underside of the manifold, and welded it onto the plenum.

Mark completed the Throttle body flange, and then worked the throttle body over a little with the mill to clean it up while I welded the throttle body flange to the plenum.