Supertech Valve Spring Kit

DESCRIPTION

Supertech valve spring kits for 94-05 1.8L (BP) Miata engines.
Includes springs, retainers, and locators.
Price is for a full set of 16, enough for the full engine.

Spring Options:
Supertech offers three options for the springs: Single spring, "Light" dual spring, and "Heavy" dual spring. The difference is in the pressure exerted by the spring. The primary factors that affect which spring you want are RPM and boost. The single spring is suitable for naturally aspirated engines and low boost applications (up to about 10 psi) where the redline remains near stock. Engines with an increased redline and/or running moderate to high boost should go with the dual spring options. As a general rule of thumb, the "light" dual spring is good for up to 8,000 RPM and/or moderate boost (up to 20 psi), and the "heavy" dual spring is good for 9,000 rpm and/or over 20 psi boost.
While the heavier springs are required for more extreme builds, Supertech notes that their valves are designed to be able to handle the extra force of all of their valve spring options, so longevity of the valve is not a concern with the strong springs. Therefore, if you're pairing these springs with Supertech valves then there is effectively no downside to running a spring that may be "overkill" for your build, and the stronger spring will just give you extra safety factor in case you mis-shift or similar and accidentally over rev the engine.

Greg here runs Supertech's heavy dual springs along with their valves in his Mazdaspeed Miata and is going on 60,000 miles on that motor!

SPECS:

SINGLE SPRING
Seat Pressure: 63 @ 33.6
Open Pressure: 157 @ 10
Max Lift: 12.90mm
Coil Bind: 20.70mm
Rate: 9.4

LIGHT DOUBLE SPRING
Seat Pressure: 75 @ 33.6
Open Pressure: 170 @ 10
Max Lift: 12.90mm
Coil Bind: 20.0mm
Rate: 9.6

HEAVY DOUBLE SPRING
Seat Pressure: 85 @ 33.6
Open Pressure: 205 @ 10
Max Lift: 12.90mm
Coil Bind: 20.7mm
Rate: 12.1

(OE Springs are 50 lbs seat pressure)