In terms of cars, I will say that I am not that familiar with IRL cars but that F1 cars certainly do create a lot of suction force through venturi effect. However, the principle is based on channeling air into a narrower surface area, like under a car, in order to accelerate its flow and create a suction effect. Thus, it depends a lot on how effective the reduction in area is under the car. For maximum effect, cars must have very deep side "skirts" which almost totally separate the area under the car from the rest of the track. F1 cars do have those "skirts" but they are very small and their dimensions are strictly regulated. If this is even more so with IRL cars, and I am not sure what the rules are, the venturi effect is greatly reduced. So Spectre30 may be right to say that the aero downforce has become more important due to rules but there is most definitely some venturi effect left. Even though I do not know the IRL regulations, one thing goes in favor of saying that the venturi effect on IRL cars is not so great as perhaps thought. A very important part of the effect is how the air exits the area under the car. This is why on F1 cars you see very elaborate "diffusers" which work as fixed mechanical air extractors. On IRL cars, this rear end is not that elaborate, you just see the gearbox which makes me think that maybe the venturi effect is not that important to them probably due to regulations which severely limits it anyway. Correct me if I'm wrong.
Catmando, that's a good point. I always believed that Skater, MTI... did not use the center pod because this makes the boat faster, a reasoning I explained in a previous post. They are winning because they are faster not because they can handle big water better. Racing does not happen in really big water nowadays anyway. A small center pod will improve rough water handling in my book. I'd rather see waves splash a V-hull shaped surface than a flat surface tunnel. It makes a softer ride. However, when we're talking about very large center pods, sometimes larger than side sponsons, I have the feeling that boats behave more like conventional V bottoms thereby producing an even better ride in the rough stuff. However, the volume of the tunnel is greatly reduced there and the cushion effect is smaller so the boats are quite a bit slower.
BTW SS930, which driver are you thinking of? Ayrton Senna or someone else?