Air Dam - Cosmetic or Functional?

Hmmm.  Part of my dream in bringing an MG up to modern standards was to add an air dam.  The ostensible purpose of an air dam is to prevent air from getting under the car.  Since air is certainly going to pass over the car, any lack of air under the car creates a vacuum which creates down force which creates more force on the tires which creates more tractive force which makes one go around corners faster.

The physics are clear but likely not so useful in autocross, where the top speed is maybe 50mph and less in all the corners.  But, I do think an MG looks better with an air dam.

The original MGB silhouette was somewhat inspired by the speed record setting works car, the EX181.

Driven originally by Sterling Moss and later by Phil Hill, the car reached 254.9mph.  Considering the engine only made 290hp, that was quite a speed!  It may not look much like an MGB but thought was to have at least a few lines from the record breaker.  In profile, one can see some resemblance in the nose and hood line:

But, you'll also notice the lower part of the nose is a big air duct, angled to push air under the car.  For a speed record, you only need enough downforce for stability, since turning, even the slightest bit, is a disaster!

The MGB didn't get anything like a production air dam until the rubber bumper cars of the late 70's.  But you can buy a retrofit at Moss Motors:

You have to drill your own bolt holes and make clearance for the bumper mounts but it is fiberglass and cuts pretty easily.  Of course you also have to paint it.

I think it makes a nice, aggressive look!  Probably no measurable performance impact but who knows?

All in all, a pretty easy upgrade with noticeable results.  If there's improvement at the autocross, I'll give it partial credit!  Happy motoring and keep on having #funwithcars !