Originally Posted by SP33DRCR
If you were getting, say, net 100hp more with the supercharger at the track, your speed down the two straights would be higher--a lot higher. That's just simple math. But it isn't. (I agree that track surface conditions and ambient temperature/humidity may play a role, but it would be small and thus inconsequential.)
I know nothing about the particular supercharger you used, or what other mods were done to accomodate the supercharger. But I think the conclusion here is that the supercharger, as installed, wasn't designed/setup for track use. Sounds like the basic issue is heat. Running with it on your car at a track when it is not performing optimally could slow you down. It is adding a 40lb lump at pretty bad location (up high, and in front of the front wheels), it will drag on the engine just like running the A/C, and it could affect the stock throttle responsiveness (which is one of the great attributes of the car), & etc. That may actually explain why your lowest low speed is actually with the supercharger on the car.
So I guess I don't find the results to be all that shocking--I'd sort of expect it.
This is why the VT2 (intercooled kit) would be much more beneficial because no matter if it's lap 1 or lap 40, you are running cool and timing is not being pulled (at least with my experience in analyzing my VBox data for 2 different track days).
I understand what radiantm3 is saying regarding the FMIC (component of the air to water system) in the VT2 that partially blocks the oil cooler but I'm actually seeing cooler oil temps on the track compared to the street given the constant airflow in a track situation...but I haven't tracked in the summer yet.