slow4dr
02-03-2005, 12:37 PM
I get this question quite often. "Are your wastegates adjustable?"
The answer is yes, not with the supplied parts though. First you must understand what a wastegate does. It bypasses a certain amount of exhaust around the turbine wheel to control the speed in which the turbo spins. On a typical external wastegate you will have two vacuum/boost ports one above and one below the diaphragm on the head of the wastegate. When you can control the vacuum/boost signal to the diaphragm you can control the boost above what the base spring pressure is.
http://bankspower.com/Twin-Turbo-images/TT-Wastegates-lg.jpg
In this picture you can see on the wastegate on the right there is a port at the top of the wastegate. This port can be used to hold the diaphragm shut longer when pressure is applied which in turn will raise the boost level by not allowing the valve to open. This is for the extreme side of boost running 20 + psi.
However, not pictured is the port on the lower side of the diaphragm. This is the one we want. If you run a vacuum/boost line to the intake manifold the wastegate will open and control boost at the exact spring pressure in the gate(6 or 12 psi included in kit). When the manifold line sees 6 psi it has enough force to push open the 6 psi spring in the gate. The Banks kit includes these lines.
Boost controllers(electronic or manual) are a function of this line from the manifold to the gate. If you bleed off some of the boost in this line you can keep the gate closed longer and raise the boost level. These controllers can be found in many different configurations. I have been using Hallman manual controllers for many years. http://hallmanboostcontroller.com/ These are great bang for buck controllers. For the guys/gals that want the best you want an electronic controller. These are a little more expensive but are still very easy to hook up. I really like the greddy Profec series. http://greddy.com/ These can be mounted inside the vehicle and can be configured to control boost in a hi-lo button switch or even as advanced as controlled by speed or RPM.
The Blow Off Valve(BOV) seems to be very misunderstood. People often think the BOV and the wastegate hold a similar function. The BOV releases pressure from the intake when the throttle is abruptly closed. The reason for this is the turbo is spinning at a high rate of speed when boost is being made. When you suddenly close the throttle plate the pressure has nowhere to go but backwards and into the turbo forcing it to stall. The BOV works off a vacuum line under the throttle plate. As soon as it sees vacuum the signal goes to the BOV opening it and releasing the pressure. This is the PSSSSH sound you hear when turbo cars shift. The air released can be routed back into the intake tract before entering the turbo or vented to atmosphere. On a MAF sensor engine management you want to route the BOV outlet back into the intake tract before the turbo as the air has already been accounted for. Some people refer to this as a bypass valve. In a MAP(speed density) you can just vent it to atmosphere.
Sorry for the rant! :_paranoid
The answer is yes, not with the supplied parts though. First you must understand what a wastegate does. It bypasses a certain amount of exhaust around the turbine wheel to control the speed in which the turbo spins. On a typical external wastegate you will have two vacuum/boost ports one above and one below the diaphragm on the head of the wastegate. When you can control the vacuum/boost signal to the diaphragm you can control the boost above what the base spring pressure is.
http://bankspower.com/Twin-Turbo-images/TT-Wastegates-lg.jpg
In this picture you can see on the wastegate on the right there is a port at the top of the wastegate. This port can be used to hold the diaphragm shut longer when pressure is applied which in turn will raise the boost level by not allowing the valve to open. This is for the extreme side of boost running 20 + psi.
However, not pictured is the port on the lower side of the diaphragm. This is the one we want. If you run a vacuum/boost line to the intake manifold the wastegate will open and control boost at the exact spring pressure in the gate(6 or 12 psi included in kit). When the manifold line sees 6 psi it has enough force to push open the 6 psi spring in the gate. The Banks kit includes these lines.
Boost controllers(electronic or manual) are a function of this line from the manifold to the gate. If you bleed off some of the boost in this line you can keep the gate closed longer and raise the boost level. These controllers can be found in many different configurations. I have been using Hallman manual controllers for many years. http://hallmanboostcontroller.com/ These are great bang for buck controllers. For the guys/gals that want the best you want an electronic controller. These are a little more expensive but are still very easy to hook up. I really like the greddy Profec series. http://greddy.com/ These can be mounted inside the vehicle and can be configured to control boost in a hi-lo button switch or even as advanced as controlled by speed or RPM.
The Blow Off Valve(BOV) seems to be very misunderstood. People often think the BOV and the wastegate hold a similar function. The BOV releases pressure from the intake when the throttle is abruptly closed. The reason for this is the turbo is spinning at a high rate of speed when boost is being made. When you suddenly close the throttle plate the pressure has nowhere to go but backwards and into the turbo forcing it to stall. The BOV works off a vacuum line under the throttle plate. As soon as it sees vacuum the signal goes to the BOV opening it and releasing the pressure. This is the PSSSSH sound you hear when turbo cars shift. The air released can be routed back into the intake tract before entering the turbo or vented to atmosphere. On a MAF sensor engine management you want to route the BOV outlet back into the intake tract before the turbo as the air has already been accounted for. Some people refer to this as a bypass valve. In a MAP(speed density) you can just vent it to atmosphere.
Sorry for the rant! :_paranoid