I know basically how a turbo works but I'm unclear on some areas. How do turbos build up boost? What does the BOV do? Wastegate? How can you control the amount a boost being made? What makes them better than superchargers?

 

How do turbos build boost - by the exhaust flowing out of the headers into the turbine housing. The exhaust passes over the turbine wheel and turn it, connects to a shaft and turns the compressor wheel to build boost.

The BOV mounts somewhere in between the turbo/supercharger and has two lines, one on the back side of the throttle body and one in front of the TB closer to the turbo. So your under boost and the throttle is open..then your at the end of the run and lift...the pressure on the front side of the throttle body spikes, and you have a vacuum in the intake, so the BOV opens to keep the pressure from spiking to high and hammering the turbo or supercharger

The wastegate allows some exhaust gas to bypass the turbine of the supercharger and go directly into the downpipe. The exhaust gas that bypasses the turbine does not turn the wheel and you do not spin the turbo with the bypassed gas. That will answer the next question.

I like a turbo better because for one you are not side loading the crank to turn the blower, which will take from probably 60HP all the way to 250+ on one of the big prochargers. I think a turbo will make more power at less RPM's than a supercharger and isn't as tough on parts.

Hope this makes sense and has helped some.

 

I still don't understand how you control the boost. With a S/C you swap pullies for different boost. How does a turbo control the amount of boost being made? When I look at turbos, on the exhaust side there is a vavle that opens, is that the wastegate?

 

yes...if there is a valve on the turbine house that is an integral wastegate and uses an acuator. You adjust that to make whatever boost you want. Another type of wastegate which most race setups have and a little neater to package is the external wastegate that is fabricated into the exhaust system.

 

To make it a little clearer, the wastegate contols the boost by allowing some of the exhaust gas to bypass the turbine. Also not all BOVs have two lines some operate off vacuum only.

 

http://auto.howstuffworks.com/turbo.htm