Q: What does an external wastegate (EWG) do?
A: It allows exhaust gases that would otherwise spin the turbine wheel causing additional boost be bled away in a more efficient and controllable manner than an internal wastegate is capable of. They also reduce back pressure in the exhaust stream by offer a less turbulent method for the exhaust gas to escape as compared to an internal wastegate. For many setups, an external wastegate provides an elegant solution to the common "boost creep" issue experienced on internally gated stock location turbos.
Q: When do I need an external wastegate?
A: One of the common times for switching to an external wastegate setup is when attempting to alleviating mechanical boost creep. Some vehicles, such as the 2009-2013 WRX, are extremely prone to uncontrolled boost creep with any modifications that free up the intake or exhaust tract, such as upgraded intake and downpipe. Combining Stage 2 mods with an EWG provides the boost control necessary to fully leverage each modification's potential!
Q: Do I need any other hardware to install this?
A: We would recommend new uppipe gaskets, but they are not necessary if they are still in good shape. At our retail shops we always recommend replacement during installation as it is a laborious process to replace them later.
Q: What size is the wastegate and why did COBB choose that size?
A: 44mm. This size was chosen as it provides capacity for the broadest range of turbocharger options. Smaller gates can be overrun by some setups.
Q: What springs does it come with and how do I know which one to use?
A: The wastegate is pre-sprung to 0.9 bar. All of the available Tial springs for for the MVR setup will be included: spring pressures from 4.35-21.75 psi. The included .9 bar spring is a good fit for most common setups. Please consult your tuner for their preference and recommendation if you have a unique or elaborate turbo configuration.
Q: Are off the shelf (OTS) maps available?
A: As of this time, there are no OTS maps available. Due to the typical vehicle set up when using an EWG, a custom tune is usually the best option.