MSD Activator Window Switch - Experiences?

[Howieau]

Hey guys Im looking at getting an MSD Activator Window Switch for my ST185 GT4 to use in controlling the TVIS (2nd set of intake runners closed at low rpm to promote torque, then open around 4500rpm to allow more flow/power). Heres a pic and caption;

http://www.capa.com.au/pics/shm_ignition_8950.jpg

RPM Activated Switches will perform a variety of functions including turning on a bulb or solenoid or triggering secondary intake runners. The 8950 switch activates a circuit when the engine rpm reaches the value of the rpm module (sold separately below). The 8956 window switch uses two rpm modules, one to activate a circuit, and the second to deactivate the circuit. This is a great feature to deactivate nitrous before the engine's rev limit is reached.

The idea of using an MSD AWS and home-made rpm module is described on the following website;
http://www.corral.net/tech/powerplant/arm/

The idea is to do 2 dyno runs, one with the TVIS connected and one without and the RPM at which the torque curve intersects is the RPM you choose for the 2nd set of intake runners to open.

Has anybody tried this or something similar? Any experiences with the MSD activator switch or effectiveness of the home-made module?

Thanks in advance.

[AlunJ]

Sounds like the same theory as smoothing out the civic type r's, their cam change rpm is deliberately set too high (in order to make the power difference more noticeable and is altered by the method you've mentioned above (two dyno runs, one on std cam and one on high-rpm) with the best point being the crossover point of the two.

Not sure about the MSD unit though, the "turn off" upper limit wouldn't be needed, that's more for nitrous use than something like TVIS, and there's no point paying for something you don't need. Have you thought about using the wiring from an el-cheapo shift light and using it to switch a relay for the TVIS?