Installed the finished intercooler and fitment ended up being spot on to what was intended. There is a lot of wisdom in the age old saying, “measure twice, cut once,” or in the case of this build…measure a few dozen times, redesign, measure another dozen or so times, realize the first idea was better, then cut.
One more shot of the finished intercooler. The clearances to the driver's side frame rail and body are fairly tight, but it is what's going to allow us to get fresh air to the turbo.
Originally there did not seem like there was going to be a good way to get the hot air from the turbo to the intercooler. There were several design iterations where the tubing would shoot out of the turbo away from the intercooler, go through a ridiculous series of bends, wrap its way under the intake tube, and finally make its way back to the intercooler. Fortunately cutting a couple of inches off the end of the turbo's compressor housing outlet and welding on a tight radius Vibrant elbow fixed this issue. This probably isn't the shortest intercooler piping done on an RX-7, but it's likely pretty damn close.
Here we have the final test fit and tacking of the intercooler cold side tube. It may not be completely noticeable at first glance, but there are 3″ to 2.75″ reducing couplers on both ends of the tube. Because there will probably be comments and questions about why someone would do this once it is seen in person, let's clear the air. Since both the elbow on the intercooler and the throttle body are cast components and much thicker than the 16ga tubing, the inside diameter of each component is nearly identical even though the outside is not.
Finish welded the cold side intercooler tube. This is 2.75″ OD, 0.065″ wall 6061 aluminum tubing.
Because who doesn't love getting new tools, here's the new tubing bead roller for better hose retention under boost. Welding a bead around the tube is a good alternative way to accomplish the same thing, but we opted to do it the easy way this time and couldn't be any happier with the results. On a side note, the WD-40 in the background is an unlikely, but great lubricant for working with aluminum. Whether forming with the bead roller, bending with the sheet metal brake, or doing general cutting and machining it does wonders.