| Lots of good info. So much that you could spend a lot of time there. I know it's been around for a while but just wanted to reiterate that it was there. Main page.
[ http://www.turbobygarrett.com ] Good read on this page.
[ http://www.turbobygarrett.com/turbobygarrett/tech_center/turbo_optimization.html ] Some hi-lites regarding charge tubing, intercoolers, intercooler mounting, BOVs and turbo oil leakage. ==============================================
Charge Tubing
The duct diameter should be sized with the capability to flow approximately 200 - 300
ft/sec. Selecting a flow diameter less than the calculated value results in the flow
pressure dropping due to the restricted flow area. If the diameter is instead increased
above the calculated value, the cooling flow expands to fill the larger diameter, which
slows the transient response.
For bends in the tubing, a good design standard is to size the bend radius such that it is
1.5 times greater than the tubing diameter.
The flow area must be free of restrictive elements such as sharp transitions in size or
configuration. For our example: ¦Tubing Diameter: velocity of 200 - 300 ft/sec is desirable. Too small a diameter will increase pressure drop, too large can slow transient response.
¦Velocity (ft/min) = Volumetric Flow rate (CFM) / Area (ft2)
 Again, for twin turbo setups, divide the flow rate by (2). Charge tubing design affects the overall performance, so there are a few points to keep in
mind to get the best performance from your system. ¦Duct bend radius:
- Radius/diameter > 1.5
¦Flow area:
- Avoid area changes, sharp transitions, shape changes
¦Available packaging space in the vehicle usually dictates certain designs Selecting a Charge Air Cooler (aka intercooler) has been made simple with
[ [ www.TurboByGarrett.com ] ]'s intercooler core page. Each core is rated for horsepower,
making it as easy as matching your desired power target to the core.
In general, use the largest core that will fit within the packaging constraints of the application. For our example:
 Another important factor in selecting the correct intercooler is the end tank design. Proper
manifold shape is critical in both minimizing charge air pressure drop and providing
uniform flow distribution. Good manifold shapes minimize losses and provide fairly even
flow distribution. The over-the-top design can starve the top tubes however. The side
entry is ideal for both pressure drop and flow distribution, but it is usually not possible
due to vehicle space limitations.
 Proper mounting of the intercooler increases the durability of the system. Air to air
charge air coolers are typically "soft-mounted", meaning they use rubber isolation
grommets. This type of mounting is also used for the entire cooling module. The design
guards against vibration failure by providing dampening of vibration loads. It also
reduces thermal loads by providing for thermal expansion.
 Benefits of Isolation:
¦Guards against vibration by damping loads
¦Reduces thermal loading by providing for thermal expansion
Blow Off Valves (BOV)
Using the proper blow off valve (BOV) affects the system performance. There are
two main types to consider.
•MAP (Manifold Absolute Pressure) sensor uses either a vent-to
atmosphere valve or a recirculation valve. ?Connect signal line to manifold source
?Surge can occur if spring rate is too stiff •MAF (Mass Air Flow) sensor uses a recirculation (bypass) valve for best drivability. ?Connect signal line to manifold source
?Position valve close to the turbo outlet for best performance (if valve can handle high temp).
?Surge can occur if valve and/or outlet plumbing are restrictive.
5. Common Causes of Oil Leakage
A properly installed turbo should NOT leak oil. There are, however, instances where oil leaks occur. The most common causes,
depending on the location of the leak, are:
Leakage from compressor and turbine seals •Excessively high oil pressure
•Inadequate drain drain is too small, does not go continuously downhill,
or the location of the drain inside the oil pan is located in a section that has
oil slung from the crank causing oil to back up in drain tube. Always
place oil drain into oil pan in a location that oil from crank is blocked by windage tray.
•Improper venting of crankcase pressure.
•Excessive crankcase pressure.
•Oil drain rotated past the recommended 35°.
Leakage from compressor seal
Excessive pressure across the compressor housing inlet caused by:
•Air filter is too small.
•Charge air tubing too small or has too many bends between the air filter
and compressor housing.
•Clogged air filter.
Leakage from Turbine seal
•Collapsed turbine piston ring from excessive EGT’s.
•Turbo tilted back on its axis past recommended 15°. And a nice turbo troubleshooting guide.
 (Total Mouse Over Hits: a Lot) www.mytwinturbo.com Watch an ECZA meet caravan! Download my Nissan 300ZX Vin/Model Lookup |
Looking at some of the info on Garrett's website. - 
