The Corvair engine has a very convenient means of connecting an intake plenum to the case and heads. Two flat surfaces on either side make it a simple matter to fasten two aluminum angles. I cut out two cardboard templates and trimmed them until the cowling fit snugly, and then cut some Home Depot Styrofoam to rough shape and installed it between the cardboard. This photo was taken after sanding to shape.

I covered the whole thing with duct tape as a mold release and to smooth out the rough spots.

I used the time-honored plastic sheet method to layout the exact shape that I'd need the fiberglass cut to...

... and laid up two pieces of 9 ounce cloth, wet out with AeroPoxy.

This makes it easy to put the glass where you want it, and ensures that the layup doesn't turn into a long skinny mess between the table and the target.

A little smoothing and it looks great.

A little coaxing and the plenum was removed and cleaned up. There's still a little more to do, but this is essentially done. It took me about three hours total to do the first one, and I'd expect the second one to take about two hours.

Here's the view the air will get just before it's forced down between those hot fins!

I think the plenum concept will work very nicely with my NACA duct setup evacuating the underside of the engine. I'll pull the oil cooler air off the backside of the passenger plenum, since it will gather more air due to the shape of the inlets. Intuition would tell you that the epoxy will soften that this plenum scheme won't work, but it's becoming common practice on many homebuilts.

More later...

Return to Mark Langford's KR2S