SUPERTECH inlet and exhaust valve stem seals Mitsubishi Hyundai 4B11 4B11T G4KF set of 16

Mitsubishi and Hyundai engines concerned

This full set of 16 seals is for the Mitsubishi 4B11 16-valve 2.0 with 5.5 mm stems and its derivatives: the 4B11-T of the Lancer Evolution X and Ralliart, the naturally aspirated 4B11 of the Lancer, ASX, Outlander, Delica D5 and Eclipse Cross, and the G4KF of the Hyundai Genesis Coupé, 143 to 446 hp depending on version, since 2006.

The 4B11 has 8 inlet and 8 exhaust valves, all fitted by Mitsubishi with the same seal MN183952; SUPERTECH follows that principle with a single integral seal. The 16 pieces of the set therefore cover the complete head; each seal fits over the guide and lets through only the oil needed.

SUPERTECH inlet and exhaust valve stem seals

On a tuned 4B11-T as on a stock 4B11, the seal lubricates the 5.5 mm stem and keeps excess oil above the guide. Over the years, heat cycles end up tiring its lip, which leaks: the 4B11 uses oil between changes, the Evo X leaves a blue cloud as the 4B11-T starts or as the G4KF picks up after idling for a long while, and carbon gradually spreads over its 16 valves and its 4 spark plugs.

SUPERTECH's VSI-M5.5V, the 4B11's integral Viton (FKM) part, matches the 11 mm guide and 5.5 mm stem of the 4B11 and the G4KF alike. With 16 pieces, this set replaces the 4B11-T's MN183952 inlet and exhaust seals in a single order, no sorting.

Stem seal technical specifications

Stem seal installation

Technical guide

The brand offered

Set up in San Jose, California, 30+ years ago, SUPERTECH, maker of the VSI-M5.5V, designs race valves plus their springs, guides and seals. X-ray, laser and ultrasound screen every batch before renowned engine builders validate it on test benches and in racing.

Inlet or exhaust?

For the 4B11, 4B11-T and G4KF, SUPERTECH keeps to one item: the integral VSI-M5.5V in Viton (FKM) dresses the 4B11's 8 inlet valves as well as its 8 exhaust ones, with a 5.5 mm stem and 11 mm guide throughout. Per SUPERTECH, the VSI-M5.5V's Viton holds 204 °C (400 °F) continuously, a clear plus on a pushed 4B11-T exhaust. A set of 16 does the engine.

When valve stem seals must be replaced

• The 4B11 uses oil, the Evo X smokes blue at start-up
• 4B11 head rebuild, valves out
• 4B11-T guides replaced
• Stiffer springs or new 4B11-T valves fitted

Vehicle compatibility

MITSUBISHI

HYUNDAI

OEM part number (Mitsubishi stem seals): MN183952

Remember the 4B11-T and G4KF uprated valves

4B11 head removed? Check the state of its 16 valves too. SUPERTECH produces uprated valves for the 4B11-T and G4KF inlet: