08 July, 2009

Making cooling ducts for the FV

One of my planned mods for the FV is to replace the cooling fan and shroud with some duct work and scoops. At higher rpm, the fan belt tends to slip enough to where the fan essentially stalls out at say 4,00rpm, even when the engine is turning 6,000rpm. With the greater horsepower of the bigger engine, my oil temperatures were climbing up to about 250 degrees F at the last race, and it was only in the mid 80s temperature wise. Without better cooling, I would never be able to run in hotter temps, or for longer sessions.

I am attempting to kill two hot birds with one cold stone. First, I want to use some air scoops mounted on the outside of the rear bodywork to suck in air and push it through duct work down onto the cylinder heads. Second, I want to also direct some air to the oil cooler.

Previously, the oil cooler was located just in front of the fan shroud intake. Not the most ideal position, since the fan is pulling air through the oil cooler and then sending that warm/hot air onto the cylinder heads. But, with the 1200cc engine, I never saw high oil temps, so there was no real reason to "fix" it.

I'm hoping that the combo of ramming air onto the cylinder heads, and providing cool air directly to the oil cooler will solve my issues.

The first part of this job is to create the internal duct work. And by internal, I mean what fits inside the rear bodywork, which is mostly exposed. The duct work will fit between the opening in the body down to the cylinder head tin. After carving out the rough shape of the ducts, I quickly realized I could simply add on a bit of extra duct work to send air to the oil cooler. Instead of having to make individual ducts, or mess about with hoses etc.

The shaping and sanding of the foam was actually a lot of fun. It took a bunch of test fitting to get it right, and each side was slightly different in final shape and size. Here is a shot of them fitted inside the engine area, but before the final shaping took place:

The oil cooler will be moved to the right and up, so that those two curved parts of the ducts are centered on the cooler.

And here is a closeup of the "passenger" side after shaping and sanding:

The upper right part of the duct in the above photo is where the air enters. The air will be ducted down and out the bottom for the cylinder heads, and across and through the upper curved pieces for the oil cooler. I'll make a small dividing wall to separate the two flow paths.

These foam pieces are essentially the male plugs, and will get wrapped in fiberglass. I can either melt out the foam with chemicals, or simply hog it out with some screwdrivers and wire brushes. Basically, a perfect example of a "lost foam" process, like how I've made motorcycle seats and gas tank extenders before.

The next part of the project is to make the outer air scoops, which will attach to the stock engine cover. I'm trying to keep things both simple, and original looking. I'm hoping the air scoops won't be that noticeable, yet provide enough area for adequate cooling.



sean said...

Sweet! I was gonna say "cool!" but that would've been too punny.

Where are the pictures of you completely covered in little bits of blue foam staticly-clung to you from the shaving/forming process?

Chris said...

wait, you want pictures of me shaving? down there????