18 Sep 2016

The third and smallest subassembly was completed, connecting the inlet duct to the intercooler assembly proper. Several pictures show the overall flow – I’m pretty happy with how the three turned out, somewhat subtle yet all-business (granted, a lot of finish-up work remains on them).

The second-to-last picture shows how well imperfections show up with the good lighting. All of this was corrected by simply using my figures, more on that below.

I’m trying something that might work great – or might not. Instead of following advice from composite experts, I’m going to: smooth out the foam plug, coat with epoxy/micro, let it cure, sand smooth, coat with mold release, cover with fiberglass. The theory is that the epoxy/micro will fill the voids in the foam, resulting in a much smoother inner surface when the foam’s removed, which the mold release will theoretically allow to just magically happen. Guess we’ll all see how well this works.

I’m debating whether to: treat the foam/roof panel as a surface upon which to lay-up the fiberglass, then pop the finished parts off the roof for finish-up work, or lay it up permanently. I started with the smallest (and least visible!) subassembly and plan to pop it off for cleaning after it cures. The inlet section though is more challenging because of how I made the plug – perhaps incorrectly in hindsight. Some of the foam is (or was) intended to be become a permanent part of the final assembly, specifically the foam ahead of the inlet proper, along with the stiffening ribs. This type of foam isn’t structural – it’s very delicate, just running your finger across it visibly removes material. It’s great for forming and finishing, not great for bearing any weight; in fact it’s why the assembly can’t be vacuum-bagged because the 15 psi of air pressure will completely collapse the foam (pretty proud of myself for figuring that out before finding out the hard way)! Meh, a solution will present itself one way or another.

Oh, and I’m using slow-cure epoxy so I don’t rush. I’ve used fast-cure and they aren’t kidding, in a matter of minutes even small batches get warm and it must be quickly spread and the composite applied. The slow-cure allows plenty of time to make sure each layer is in place and any bubbles dealt with. The only downside is that once it’s applied, work on that part has to stop for the rest of the day.