SUPERTECH inlet and exhaust valve stem seals Subaru Toyota FA20 4U-GSE set of 16

Subaru and Toyota engines concerned

This full set of 16 seals targets the 16-valve 2.0 boxer with 5.5 mm stems shared by Subaru and Toyota: FA20D and FA20C of the BRZ (ZC6) and GT 86 (ZN6, 4U-GSE), plus FA20, FA20E and FA20F of the Forester SJ XT, Impreza GJ, Legacy BM / BR / BN, Levorg, Outback BS and WRX, 200 to 301 hp, since 2012.

Each FA20 carries 8 inlet and 8 exhaust valves, all fitted by SUPERTECH with the VS-SU5.5-EI: the 16 pieces of this set redo the FA20 head in one go. Sitting on the 4U-GSE guide, each VS-SU5.5-EI lets only the needed oil down to the stem.

SUPERTECH inlet and exhaust valve stem seals

In a GT 86's FA20 as in a Levorg's FA20F, the seal holds a minimal veil of oil on the 5.5 mm stem and keeps the surplus head-side. After years of thermal cycles its lip loses suppleness and lets oil by: the BRZ needs a top-up before the oil change, a blue cloud follows the FA20's cold start or a 4U-GSE pulling off idle, and 16 valves and 4 plugs carbon up.

SUPERTECH makes the VS-SU5.5-EI in Viton (FKM) for the FA20's 9.9 mm guide and 5.5 mm stem, with a 12.2 mm outside diameter. As this VS-SU5.5-EI serves both sides, the 16 pieces of this set handle the 4U-GSE's inlet and exhaust at once.

Stem seal technical specifications

Stem seal installation

Technical guide

The brand offered

Settled in San Jose, California, for 30-plus years, SUPERTECH, home of the VS-SU5.5-EI, designs race valves plus springs, guides, seals. The VS-SU5.5-EI, like every part, goes through ultrasound, laser and X-rays, then onto recognised tuners' dynos.

Inlet or exhaust?

For the FA20, FA20D, FA20F and 4U-GSE, SUPERTECH has one part number: the VS-SU5.5-EI in Viton (FKM) dresses the 4U-GSE's 8 inlet valves just like its 8 exhaust valves, 5.5 mm stem and 9.9 mm guide on each FA20 side. SUPERTECH quotes 204 °C (400 °F) continuous for the VS-SU5.5-EI's Viton, reassuring on the FA20F exhaust. One set of 16 does the FA20.

When valve stem seals must be replaced

• GT 86 needing top-ups, FA20 blue smoke when cold
• 4U-GSE head stripped for an overhaul
• FA20F valve guides changed
• Race springs or valves going onto the 4U-GSE

Vehicle compatibility

SUBARU

TOYOTA

Remember the 4U-GSE and FA20 uprated valves

FA20 open: take the chance to inspect its 16 valves. For the FA20D and 4U-GSE inlet, SUPERTECH offers uprated valves: