Ok....i'm not THE turbo expert, but if anyone here has heard of Corky Bell raise your hand!
Seems like the 20bucks i spent on Maximum Boost down at Books-A-Billion brought me up to speed pretty well on turbos and superchargers. I'd suggest reading it three times before attempting any remotely related to turbos or forced induction!
Do i have a custom one-off forced induction machine? Yup, its a 1980 motorcycle. It'll knock your socks off. I think i spent like 50bucks on it too. Just goes to show what a decent amount of understanding does, versus drooling over the import mags and their shiny kits for a few grand or so.
Also, not raggin on anyone here, but turbos arent free! All of those who want to think of superchargers as power-sapping devices listen up! NOTHING is free in life, energy cannot be created or destroyed, its one of the most basic principles of physics. It only changes form. Example: clap your hands and you hear a sound and your hands are hot. The force of slapping skin together and stopping it is transferred into sound and heat energy. Ok, that was an oddball example, i'll give ya that one! Now lets talk cars:
The exhaust gas is pushed out of the cylinders by the piston on it's upstroke. There is some help of the hot gasses expanding and seeing an open path to the tailpipe. It screams out, like a baby being born. But, it still pushes against the piston, and the piston has to push it back out, and the other pistons are turning the crank trying the push that piston 'up' so it's exhaust stroke can be finished. Action and reaction, yet another physics law. Hmm...perhaps that stuff was important back in grade school, highschool, and perhaps college. Just like someone on rollerskates pushing on someone with regular shoes, the shoes are the piston and the skates represents the spent gasses trying to exit the cylinder. The 'shoes' have to be rigid or push somewhat, or else theyd simply roll-away like another pair of skates!
We all know that less-restrictive exhaust systems are best, right? Well, a turbo is a HUGE restriction. Try blowing on a toy windmill really hard or trying to turn a house fan by blowing on it. Thats not even close to what the exhaust has to do! It takes on average about 15hp to do forced induction on a small honda motor BLOWN OR TURBO'D. The larger 'big-boy' street rods and muscle cars can use a few hundred depending on boost. Horsepower is horsepower, its either going through a belt or the piston.
Another 'downside' of turbos is the inherent detonation problem. Why? The cylinders have exhaust gasses in them longer and the manifold supplying the turbo is quite hot, which transfers heat back to the cylinder, which can create 'hot-spots' and a generally hotter chamber, the two enemies of a non-detonating motor. The blown motors usually can blow some intake charge out the exhaust valves and wash any old, hot gasses out with it. This cools the chamber and allows a denser charge with less chance of detonation. All of this is dependant of cam timing, overlap, etc. True, some of the charge is 'lost' out the non-restrictive tail pipe, but is that really of consequence? A denser, more stable charge is what we are after, right? Intercoolers, water-injection, and engine management systems are all trying to get a decent amount of charge in there and ignite it with confidence.
So, get a copy of Maximum Boost, Street Supercharging, and Turbochargers from any bookstore or shop online for them. Happy forced induction reading!