Reinforced inlet valves TOYOTA GT86 FA20D 4U-GSE

TOYOTA engines covered

The 4U-GSE, known at Subaru as the FA20D, is a 1,998 cc 16-valve petrol flat-four with an 86 mm bore and stroke. It powers the Toyota GT86 (ZN6) from 2012, with 200 to 207 hp depending on version.

The engine has 8 inlet valves, two per cylinder. A sharper camshaft, a raised rev limit or forced induction push them well beyond their stock duty.

SUPERTECH and FERREA reinforced inlet valves

The inlet valve lets the fresh air in, drops back onto its seat at every closing and slides constantly in its guide, dozens of times per second at high revs. It runs between 400 and 550 °C: in this range, the original chrome-silicon steel falls from 500 MPa at 500 °C to 250 MPa at 600 °C, 50 % less strength.

SUPERTECH makes them from EV8 racing stainless steel, which keeps 650 MPa at 500 °C and 550 MPa at 600 °C, 30 % and then 120 % more than the original steel. Their black nitriding hardens and smooths the surface: the stem rubs and wears less in the guide. FERREA adds two series: Competition Plus, 20 % stronger when hot and under fatigue, with a seat that wears 25 % more slowly, and the 6000 Series. For the 2015 version, both series are offered in a special alloy.

The range includes a 35.0 mm head in standard size, 103.3 mm or 105.0 mm long, and a 36.0 mm head in +1 mm oversize at 105.0 mm, all with a 5.46 mm stem. On the +1 mm size, the wider head opens a larger passage at the seat: the cylinder fills better and the engine gains power, with the inlet seats cut to the new size. FERREA offers the same 35 and 36 mm heads, 103.45 mm or 105 mm long.

Inlet valve technical specification

SIVN-1050-2-8 and SIVN-1052-2-8: longer valves, intended for the GT86 from 2014.

SIVN-1050-8, SIVN-1050-2-8 and SIVN-1052-2-8: undercut stem under the head and back cut.

FERREA flat-head valves: 103.45 mm long for the GT86 from 2012 to 2014, 105 mm for the 2015 cars.

Fitting details

The +1 mm size requires the inlet seats to be cut to 36.0 mm, workshop work to plan with the cylinder head rebuild.

Technical guide

Our brands

	SUPERTECH works out of San Jose, California, and has supplied valvetrain parts for racing engines for more than 30 years: valves, springs, retainers and guides. Each part number starts from a specific cylinder head, goes through ultrasound, X-ray and laser checks, then is proven with engine builders, from drag strip to circuit.
	FERREA Racing Components was born in 1978 in Fort Lauderdale, Florida, from two Argentinian engine builders. The brand forges its valves in one piece from steel bar, then machines them completely on CNC, and supplies NASCAR as well as drag racing engines.

How to choose

The size is chosen according to the condition of the inlet seats and the filling wanted; the length depends on the year of the GT86.

When reinforced valves become necessary

• Higher-lift camshafts or stiffer springs
• Raised rev limit
• Turbo or supercharger fitted
• Cylinder head rebuilt for circuit, hill climb or rally
• Original valves marked, worn or already reground

Compatible vehicles