Well it ain't an F1 race car, and their ports/trumpets are polished, then again, they're crackin over 18,000rpm.

F1's aren't very efficent engines. They have a lower effective BMP (Brake mean Pressure) than a V8 supercar.

IIRC the variables in the boundary layer equation are:

Fluid viscosity
Fluid density
And
Length of the surface.

I'll dig up the whole equation and stick it up in a few days so you can have a bit of a play with it yourself and see what I'm trying to get at.