Opposed Bead Stopper Type Metal Gasket for the FA20 engine of 86/BRZ provides higher bore sealing durability than a stock gasket.
2 types of the gasket are available. One is t0.5 increased compression ratio type for an NA engine (ε12.6←12.5, Supercharger installable, Endurable approximately 300ps)and another type is t0.7 high engine output type for a supercharged engine (ε12.4←ε12.5, Endurable approximately 600ps with supercharger)

■Feature

＜POINT-1＞ t=0.7mm for Supercharged Engine
The t=0.7mm type utilizes a stopper taller than the t=0.5mm type to provide higher bore seal durability. With a stock pistons, the compression ratio is reduced only by 0.1; it allows to maintain high heat efficiency.
Compression Ratio
Stock Thickness: t=0.6mm (ε12.5) HKS Thickness: t=0.7mm (ε12.4)

＜POINT-2＞ Maintain a high seal with high pressure!
Both types are endurable against high engine output. Stopper structure of the bore seal is separated type so it prevents leakage even under high gas-pressure at high engine output.

＜POINT-3＞ Contact surface pressure is improved!
Special coating was applied on the head side and cylinder side to improve sealing performance when tightening the bolts.

＜POINT-4＞ Bore seal pressure was confirmed in figures. (See the diagram below.)
 

(Contact Surface Pressure Measurement)

(Structure Comparison)

　　NA　t=0.5
　　* Comperd to stcok, bore seal is independent and has higher seal surface pressure,  therefore same amount of stopper, bore seal is stronger.
　　* Thinner than stock and compression ratio is 0.1 highe

　　Supercharger　t=0.7
　　* Comperd to stcok, bore seal is independent and has higher seal surface pressure, therefore bore seal power is much stronger.
　　* Thicker than stock and compression ratio is 0.1 less than stock

　　Stock　t=0.6
　　* Bore stopper is similar to the other seal and ther surface pressure polymerize, it has lower seal ability than the independent type