window switch basically means that you have a certain band that you can spray or that it will be set to spray. WOT switch is a little different than a window switch. WOT will allow you to spray when you are at WOT, while a window will only let you spray at certain bands. the benefit to the window would be to tune for nitrous and keep the stress down by only spraying at certain times. basically, having a required RPM to activate.
the system that lordworm is talking about would have it's advantages in tuning for nitrous and for always having a power adder. it sounds rough, but it is probably the safest way to do it, since you could tune for it the same way you would tune for boost. the disadvantage is that i wouldn't let anyone drive my car again if i built it that way.
The tune doesn't really change though, since its a wet system. Both a microtech input, and output are used to operate the system..
The complete logic of the circuit is:
(IF) master arm switch (AND) wot switch (AND) microtech output RPM trigger switch are all on (THEN)
Provide power to microtech input so that the microtech can back out the required timing (AND) activate the fuel and nitrous solenoids.
That is to say, that if any of the arming switches in the circuit are still open - the nitrous will not activate - and the tune will be identical to his regular daily driven NA tune.
The "tuning" in this system is done via the nitrous and fuel jets - the nitrous is saturated with fuel in the fogger, at the correct A/F ratio - and squirted into the plenum, where it is drawn into the runners and mixed with the normal injected fuel. Twilight has his jetted marginally on the rich side for safety.
The one rather scary thing about this set up is that you don't really have a great deal of control over when/how the nitrous comes on...once the circuit is fully closed its on - and if you're not expecting it, it can be a handful. I remember driving it out at the roads behind the airport to help tune it...and wasn't expecting the kick in the guts at 4000rpm.... its nothing like a turbo set up - turbos you get a "ramp" of power - nitrous is just there, immediately...
The only part of the tune that ever really needs to change on a nitrous set up is the removal of 2 to 4 degrees of timing for ever 50hp shot of nitrous.
Back on the subject of window switches etc - a window switch is usually used in conjunction with a WOT switch, because its not overly safe to run nitrous at partial throttle - window switches, RPM activation switches (what Twilight uses) or push button switches generally just control the turning on of the gas, when the other switches in the system are active. The RPM activation method is probably best thought of as an "open ended window" switch - theres no upper deactivation threshold. The only advantage it has over pushing the button manually is the predictable, consistent activation of the nitrous which is CRITICAL for consistent ET's in dial-your-own handycap racing - nitrous activated by a manual push button is notoriously inconsistent...the set up Twilight is running has basically dropped his PB ET by half a second, with no impact what-so-ever on his consistency.
