This artical is for those of you that are not familar with how Turbos work. Basically they are a high volume air compressor that uses the exhaust gas heat to spin the compressor. Therefore the Motor needs to see a load in order to produce enough heat and exhaust flow to spin the Turbine. Typically 1st gear does not produce enough load unless it is a very narrow Ratio or climbing a hill and at a much higher RPM. 2nd gear is were I found a Turbo shines. The more air and fuel that can be pumped thru the Motor the more power it makes. There are two seperate systems in a Turbo. The Exhaust side Turbine and the Intake air side compressor. The Boost pressure is controlled by a Blastgate. The Blast gate is a valve that has a Pneumatic diaphram Actuator that monitors the air pressure going to the motor and opens up to release the exhaust at a specific setpoint (IE; 5psi) before it gets to the turbine to slow it down. The BOV is an air pressure relief valve. When the compressor is spinning at around 80,000 RPM the last thing you want to do is stall it. Two things happen, you lose Boost and its hard on the Turbo. When you let off the gas between shifts the throttle plate closess abrutly causing a pressure spike and with out the BOV it stalls the Turbo. The BOV monitors the Intake manifold Vacumme pressure and releases the Air Intake pressure allowing the compressor to continue to spin fast enough to maintain boost. When air is compressed it becomes very hot and that is were an Intercooler comes into play. It is merely an air cooling radiator. Although an Intercooler is not nessasary for a low boost motor, by cooling the Incoming air to the motor it allows you to run higher boost pressures and lowering detanation. One thing to keep in mind with a Turbo system is that under Boost the motor requires much more fuel to mix with the much higher air flow rate (CFM) being pumped thru the Engine. Also the timing usally needs retarded above a few PSI of Boost. This is were EFI engine management plays a major roll in a Turbo Motor. It allows you to fine tune the Air/Fuel Ratio and Timing so that you can achieve the most Horsepower and Torque with out sacrificing the motor. Also for the record Its done with carburation everyday and seems to work just fine.
Water cooled Dry Sumped Subaru Powered Turbo Charged Fuel Injected 2500CC Tank. Oh Rah! He who dies with the most Toys not only wins, He also wears them out!