We Test Synapse Engineering’s Synchronic Blow Off Valve and DV Diverter Valve

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The stepped piston was a great innovation for these devices for several reasons.  The first is that most devices of this nature are operated by intake manifold vacuum or boost pressure pushing or sucking on a flexible rubber diaphragm backed by a spring.  This is a decent and cheap way to provide operation of pneumatic controls. 

You can see the steps in the Synapse piston here.  The valve is good quality, all metal and good seals, no cheesy breaking and leaking plastic bits.  A piston means fast working and high lift of the valve.

Good quality wastegates and BOV’s use a high temperature silicone rubber diaphragm reinforced with nomex, a heat resistant fabric.  Cheap fake Chinese stuff uses recycled toilet plungers for the diaphragm. The limitations of the diaphragm are that it is prone to wear and tear; it is elastic and flexible so it adds lag and hysteresis to the system and that it has limited travel and control of valve lift.

A conventional BOV uses a rubber diaphragm to move the valve.  There is nothing wrong with this but the rubber’s travel is limited, restricting valve lift and the elasticity slows valve response very slightly.  A lot of high quality valves are made like this.  This valve has a diaphragm made of good high temp silicone reinforced with nomex.

Going to a piston to control the valve eliminated these problems associated with diaphragms. When a normal fast shift can occur in 250 milliseconds and turbo boost response can also be measured in milliseconds, having fast BOV and wastegate response time can be an advantage.

Peter was always telling us of the virtues of his Synchronic Blow Off Valves and wanted us to test one but we were somewhat skeptical that just a simple BOV could make that much difference in performance, especially on a car that had a reasonably good set up engineered by the factory so the valve sat on our desk for a while.  We were planning to install the valve on our Project Evo IX but the IX had a much improved valve from the crappy leaking plastic valve found on the older XIII model that already worked quite well.

HKS BOV’s are good parts, this fake Chinese HKS part uses rubber of unknown origin, probably melted down old toilet plungers for the diaphragm.  Death to the makers of fakes!

Crappy, leaking fake Chinese HKS part’s internals are low quality and will quickly fail.