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email Paul

Interesting Correction

I love the anonymous info I get!

After the Nazareth CART race I wrote a trip report (Eagle 997 Aero Details) with this photo and the following description of a funny-looking aero doo-dad.

It took me a while to figure this out and I might still be wrong. This is the right side of the sidepod below the engine cover. The front opening is a scoop for engine air. The turbocharger compressor is mounted there just inside the engine cover. Behind that scoop this device is concave leading to another inlet. I think this acts like a NACA duct spoiling air into an inlet for cooling air for the elevated exhaust system. The engine inlet scoop has some drag penalty but putting that other inlet behind it might increase cooling flow without any additional drag. Very clever!

Three months later I received and email message that corrected me

You got it backwards on the Eagle "turbo tongue" - the back opening is
the inlet to the turbo. the front opening is for shock cooling and
serves to extract the nasty air in the corner of the bodywork.

The next message had a more elaborate explanation of the device.

Anyway, the neat thing about the "turbo tongue" is how it draws air into
the turbo intake even more efficiently than the scoops you normally see.
Air from up to 2 feet away becomes "attached" to the tongue surface
thereby forcing it into the turbo inlet actually creating positive
pressure. This works much like the underside of the wings where most the
work is done. Any particles in the air stream cannot "make the turn"
because their velocities are too great. This allows the inlet particle
screen to be left off. These screens scrub about 30% off the inlet air
velocity, so simply removing a screen makes a big difference at least
until something is sucked into the inlet. The turbo inlet sees about
1000 CFM of airflow!

Interesting, eh? Does anyone have a further comment?