I just found this today, looks like it applies to this thread.
Splitter or Air Dam – Which Design is Best? - Mazda Miata
cfd | Hancha Blog
Quote:
CFD Models
1. Stock 1990-1997 Mazda Miata
2. Stock 1990-1997 Mazda Miata at a 4in Ride Height
3. Small Front Air Dam at 4in Ride Height
4. Small Air Dam with Splitter at 4 in Ride Height
5. Large Air Dam at 4in Ride Height
6. Large Air Dam with Splitter at 4in Ride Height
Note: The air dam and/or splitter is 2 inches off the ground in study 3-6
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I think the stock ground clearance for the Mazda Miata is 4.6-inches.
From what I can tell, just lowering the car about 1/2" increases the drag from Models 1 to 2.
However, going down via air dam/splitter to 2-inches gives better numbers than stock (Model-1).
Quote:
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Lowering a vehicle will increase the downforce by increasing the velocity below the vehicle. This does however increase drag.
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