SUPERTECH inlet and exhaust valve stem seals MINI / PSA Prince EP6 set of 8

MINI, Peugeot and Citroën engines concerned

This set of 8 seals is for the 16-valve 1.6 "Prince" developed jointly by BMW and PSA, 5 mm stem: MINI N12B16A, N14B16A, N14B16AB, N14B16C, N16B16A, N18B16A and N18B16C (R55 to R61), Peugeot and Citroën EP6, EP6C, EP6DT, EP6DTS, EP6CDT and EP6CDTX (207, 308, 3008, 408, 5008, C4, DS3), from 2006.

Each Prince head carries 8 inlet and 8 exhaust valves, all capped by the same SUPERTECH integral seal. A set of 8 therefore fills one complete row; two sets dress all 16 valves. The seal rests on the guide and filters the oil lubricating the stem.

SUPERTECH inlet and exhaust valve stem seals

From the 120 hp VTi to the 211 hp THP, the Prince asks its seals to leave a thin oil film on the 5 mm stem and send the rest back up into the head. Heat after heat, the rubber loses its suppleness and weeps: consumption climbs, bluish smoke appears after a night outdoors or on the throttle after a long stop, and both valves and plugs gather deposits.

SUPERTECH's VSI-MIN-R56 is an integral seal moulded in Viton (FKM), sized to the original guide and a 5 mm stem. The 8 pieces of this set serve one row, inlet or exhaust as you choose: one and the same seal for both sides of the head.

Stem seal technical specifications

Stem seal installation

Technical guide

The brand offered

For over 30 years, SUPERTECH has engineered competition valves together with springs, guides and seals in San Jose, California. Output is checked series by series with ultrasound, radiography and laser, then proven by top engine builders on the dyno and in racing.

Inlet or exhaust?

For the MINI N12 to N18 and the PSA EP6, SUPERTECH chose a single seal: the integral VSI-MIN-R56, in Viton (FKM), suits the 8 inlet valves and equally the 8 exhaust ones, with a 5 mm stem everywhere. By SUPERTECH's figures, this Viton takes 204 °C (400 °F) continuously, leaving headroom on the exhaust side. Count 2 sets of 8 per engine.

When valve stem seals must be replaced

• Rising oil use, blue smoke on a cold start-up
• All 16 Prince valves out for a rebuild
• Worn valve guides replaced
• Uprated springs or valves about to be installed

Vehicle compatibility

MINI

PEUGEOT

CITROËN

OEM part number (MINI stem seals): 11 34 0 033 950 (complete set, N12, N14, N16, N18)

Remember the 1.6 Prince uprated valves

With the head bare, look at the 16 valves too. For the inlet, uprated SUPERTECH valves exist for the 1.6 Prince engine: