Reinforced exhaust valves Mazda MZR 2.3 DISI turbo L3-VDT

Mazda engines covered

The L3-VDT is the 2.3 litre direct injection turbo of the MZR family: a 2,261 cc four-cylinder with twin camshafts and 16 valves, built from 2005 to 2013 for the Mazda 3 MPS, Mazda 6 MPS and CX-7.

It has 8 exhaust valves, two per cylinder. The reinforced valve keeps a 30 mm head at standard size and a 104.7 mm length, with a 5.97 mm stem reduced to 5.5 mm at the tip, specific to this turbo version.

SUPERTECH reinforced exhaust valves

On a turbocharged engine such as the L3-VDT, the metal of an exhaust valve head goes beyond 1,000 °C, against 760 to 870 °C naturally aspirated. Nearly 75 % of that heat leaves through the seat and 20 % through the guide. An EV8 family steel keeps 550 MPa at 600 °C but only 300 MPa at 800 °C: with more boost, the head overheats, distorts and the seat stops sealing.

SUPERTECH makes it in Inconel, a nickel-based superalloy that holds 860 MPa at 730 °C and 554 MPa at 815 °C, about 85 % more than the reference steel near 800 °C: the material to choose for a turbo engine running raised boost.

Exhaust valve technical specifications

MAEVI-2301D-6MM-8 has a 30 mm dished head and a 5.97 mm stem narrowing to 5.5 mm at its end.

Valve fitting

Before refitting, check that the original collets sit correctly in the groove of the 5.5 mm tip.

At standard size, the 30 mm head bears on the factory exhaust seats, simply recut.

The GDE-DUR16-6MM-8 reinforced guide is fitted with the original 6 mm valve stem seal.

Technical guide

Our brand

SUPERTECH Performance, a Californian maker of competition valves for more than thirty years, offers one Inconel exhaust valve at standard size for the L3-VDT, with the 6 mm stem of the turbo engine.

How to choose

A single version is offered for this engine:

When reinforced valves become necessary

• Raised boost or bigger turbo (Inconel version)
• Higher lift camshafts
• Track use
• Cylinder head rebuild with burnt or distorted exhaust valves

Vehicle compatibility

OEM part number (exhaust valve):

Don't forget the inlet valves

When an L3-VDT cylinder head is off, take the chance to change the inlet valves and the valve stem seals as well.