The Full Bolt on SR20 Engine, Part One, The Basics

The Greddy FV blowoff valve is a new innovative design. With FV blowoff valves the valve itself can float from the diaphragm and its spring on its own separate spring. This eliminates the problem of the blowoff valve opening at idle or on overrun recovery.  If the valve opens under these conditions, it can affect idle quality and stability and cause stalling on revving or overrun recovery.  Traditionally, to stop the valve from opening like this the valve spring preload had to be adjusted stiffly.  This made the valve unresponsive to vacuum operation when the throttle was shut under boost. If the spring was preloaded lightly to make it more responsive, there was also a chance it could blow open under boost pressure and become a huge boost leak.

With the FV valve, under high vacuum conditions, the diaphragm floats away from the valve, and the valve is held closed by its independent low-tension spring.  This gives idle and rev overrun stability. The valve’s spring tension is enough to ensure that boost pressure cannot blow the valve open.  When the valve’s diaphragm sees boost pressure, the boost pressure works through the diaphragm to help hold the valve shut.

The Greddy FV valve is always closed when it should be closed, fully open when it should be open, and still very sensitive even though it doesn’t flutter, cause driveability issues, or leak boost.  It’s a simple yet perfect solution to make the ultimate BOV

Although we will end up not using it due to our large 3″ inlet on our turbo, if you were to use a stock-size turbo inlet the Greddy air intake with its smooth bends will be a really good choice. We are not fans of the air filter but we love the rest of the intake’s construction.   We will have to fabricate our own intake and will use a cone-type filter with a velocity stack-type entrance such as the Jim Wolf Technology POP Charger.

When going for more power, bigger injectors are a must. We will be running a set of DeatschWerks 1200cc min injectors so we can have enough headspace to run E85.  The injectors use tried and true Bosch Motorsports EV14 internals as the core .

The DeatschWerks injectors are characterized and come with a flow chart showing the flow data at 450 points. This is a great help for tuning. The injectors come in flow-matched sets that are dynamically flowed and matched and a low pulse width range, a transitional range, a linear range, and wide open static flow.  This is stuff that was previously only done by a few companies on expensive injectors.  Typically if injectors are sold as flow-matched sets they are only matched at wide open static flow, not the other flow states that make up a large part ofand injectors driveability and response.

The DeatschWerks injectors come with these plug-and-play pigtails so adding them to the OEM Nissan harness will be a piece of cake!  If you are going to be running the OEM fuel rail DeatschWerks also has big capacity OEM-style side feed injectors for those applications.


    1. What we wanted was inexpensive, simple and the ability to combine with any lash up of OEM and aftermarket parts to make this a pure bolt on with no fabrication needed. We know about Artec stuff, it just doesnt meet any of those criteria.

  1. Hey Mike!

    Great information!

    Question. If you were to choose between the GEN 2 GTX, 2860r or 2867r for this build, what is your pic?

    Thanks! D

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