I know that a turbo has different parts to it than a supercharger application, ie. BOV, wastegate, turbo timer, boost controller. I was wondering what each individual part does. How does the turbo know how much boost to build up? What does the BOV do, internal/external wastegates? What is a turbo timer? I want to gain a better understanding of how a turbo setup REALLY works.

Kevin

 

The wastegate controls how much boost the turbo builds. It is basically a gate in the exhaust stream before turbo that remains closed until a specified boost pressure is reached. When that pressure is reached it opens allowing exhaust gases to bypass the turbo therefore keeping the turbo from spinning faster and building more boost.

A BOV is placed between the compressor outlet and the throttle plates. When the plates are open the motor is reving (duh) but if the plates shut quickly (letting off throttle to shift etc) the turbo is still spinning because exhaust exiting the motor is still driving it. This extra air being blown towards the closed throttle plates has no where to go, other than back out the turbo, which is not good for the turbo. Rather than allowing this air to exit back out the turbo the BOV opens from the pressure and releases the air.

A turbo timer keeps the engine running after you have removed the keys from the ignition to allow cool oil to circulate through the turbo. Turbos get very hot and the heat breaks down the oil if it is left in the turbo which leaves nasty grime on the bearings in the turbo. This is called "coking".

This is a really basic explanation, I'm sure some of the turbo experts on here can elaborate much more.

 

turbo info
here is the basics, let me see if i can find something better

 

another
turbo info

 

do some looking around here:

http://www.gnttype.org/techarea/techpage.html

probably the biggest repository of turbo based knowledge anywhere.

 

Its been said before and I'll say it again...
Maximum Boost by Corky Bell
Its a great tech book and can be understood by the average person.

 

This man speaks the truth. I love that book.

Turbos=Torque
Torque=Fun

 

in my opinion, turbo timers are useless unless you like boosting into parking spots or your driveway or your at the track hotlapping like no ones business. just change the oil every 2500 miles and you'll be fine...no point in spending 100 dollars on something thats going to keep the engine running, and still pumping that hot exhaust gas through the hot turbo, and only get hotter cause no air is flowing through the radiator and that oil is still gunna sit in there once the turbo timer goes off, and its going to be just as hot..

i boost controller is somewhat like a wastegate, basically if you have an internal non adjustable wastegate, you would use a boost controller...you have a manual (MBC) or electronic (EBC) a manual can be made for about 5 dollars at home depot (What i do)

and internal wastegate is a wastegate that is built into the turbo itself...and external wastegate, such as a TiAL, is put on the exhaust piping, before the turbocharger, and does what is stated above, regulates pressure.

another thing with turbos, from experience, they tend not to like synthetic oil, ive lost a turbo cause the oil seals went bad, for some reason synthetic just chews them up.

misconceptions...people say they want to run 15psi...this does nothing information wise...15psi on a T25 and 15psi on a T76 are two totally different airflow ranges.

turbos love heat(exhaust wise) hot expanded gas will spool it quicker.

different types of turbos aswell, examples are, air/oil/water cooler, air/oil cooled etc etc.

turbos have an exhaust and intake wheel...each have an independant A/R...the smaller the exhaust AR is, the quicker it will spool..the smaller the intake A/R is, the less air it will suck/push

those are some of the basics, some may not like my views of the turbo timer and turbos liking heat, but thats just my honest opinion.