Must clear this up!

I am almost sure of all these answers but my stupid friend needs to argue about EVERYthing, so please enlighten us.

What exactly does VTEC do?
Whats the diff between 4WD and AWD
What is it that the stealth and Mitsu GTO have in common?
How long (commonly) can a car redline untill it overheats/blows up?
how does a turbo timer work?
Can N2O really blow up?
is their a diff. procedure for adding N2O to a Turbo/supercharged car?

Thanks.

I'll answer the ones I know...

What exactly does VTEC do?

VTEC basically is an adjustable cam, so while doing normal daily driving it's a nice and smooth, but under higher RPMs it switches to a more aggressive cam for more power while racing.

Whats the diff between 4WD and AWD

There are a few signifigant design differences between 4WD and AWD, but I'm not competant enough to explain them. However, the gist of it is that AWD is "always on", while 4WD is used more in trucks and SUVs with the choice of putting all power to the front, all power to the rear, or using all four wheels.

What is it that the stealth and Mitsu GTO have in common?

As far as I know, the GTO is the European 3000GT. But I may be wrong, I'm not sure. However, if that is the case, then the Stealth and 3000GT were, for all intents and purposes, twins. Slightly different body styling, and that's about it.

How long (commonly) can a car redline untill it overheats/blows up?

I don't know really, never tried it myself. But I would imagine it depends on how far you are over the redline. I would definitely advise against any further testing on this subject.

how does a turbo timer work?
Can N2O really blow up?
is their a diff. procedure for adding N2O to a Turbo/supercharged car?

I'll pass.

Redlining vs. Blowing up all depends on how strengthened your internals and cooling systems are.
redlining a crappy car is going to do more damage than redlining a racing engine. too broad a question to really answer.

VTEC is a variable valve timing, which is electronically controlled. it is basically infinitely variable, tot he extent that depending on a variety of factors (air temp, RPM, engine temp, fuel, etc) the VTEC system tries to find the best valve timing for efficiency at low RPM's and Power at high RPM's.

N20 itself is not combustable, but it adds a cool, dense aircharge to the engine which, when coupled with more fuel, adds power to the engine.
It is possible to "blow up" an engine, however, by using too much nitrous.

Using nitrous on a car with forced induction is different in that you cannot (generally) use as much, because the incoming air is already partially compressed, and adding too much can damage the engine. usually the timing must be specially controlled which is to say SEVERLY RETARTED, usually in the neigborhood of 15-20 degrees when using nitrous with a turbo/supercahrger.

A turbo timer is designed to keep the engine idling after the ignition key is removed. This prevents hot oil from "coking" and clogging up the oil lines of the turbocharger, which could cause failure.

the other questions were already adequately answered.

N2O is 2 parts oxygen 1 part nitro gen. Not flamable at all. But it does provide the combustion chamber wits a dense carge of air due to the fact that it has 2 parts oxygen and 1 nitrogen.

If there were a fire, and the bottle burst a leak then it woul act like an explosion. Because the extra oxygen would help accelerate the flames. As well as if you leave your bottle heater on to long the bottle temp will rise and will eventualy rupture causing an explosion.