Reinforced exhaust valves Mitsubishi 4G63

Mitsubishi engines covered

The 4G63 is the Mitsubishi 2 litre, 16-valve twin-cam four, naturally aspirated or turbocharged (4G63T); it built the reputation of the Eclipse and above all the Lancer Evolution, in rallying as well as road tuning.

It has 8 exhaust valves, two per cylinder, with a 30.5 mm head and a stem of about 6.5 mm. On turbo versions they live with very hot burnt gases, all the more so when boost is raised.

SUPERTECH and FERREA reinforced exhaust valves

On a turbocharged engine, the metal of an exhaust valve head goes beyond 1,000 °C, against 760 to 870 °C naturally aspirated. About 75 % of the heat leaves through the seat and 20 % through the guide. An EV8 family steel keeps 550 MPa at 600 °C but offers only 300 MPa at 800 °C: the head sags, fatigues and ends up leaking.

FERREA offers its Competition Plus in Super Alloy, a nickel-based alloy quoted 20 % stronger when hot with a seat life extended by 25 %, and its 6000 series in special alloy. SUPERTECH adds black nitrided stainless steel, Inconel, a nickel-based superalloy that keeps 860 MPa at 730 °C and 554 MPa at 815 °C, about 85 % more than the reference steel near 800 °C, and a Nimonic version with a sodium filled stem that carries heat from the head down the stem.

At +1 mm oversize the head grows to 31.5 mm with no change of stem or length: burnt gases leave more easily, with 10 to 12 cfm more flow per millimetre of head, and the 8 exhaust seats are machined to that diameter.

Exhaust valve technical specifications

F6025, F1825P, MEVN-1007 and MEVI-1007 are standard size; F6054, F1454P, MEVN-1009, MEVI-1009 and MEVI-1009-HS are +1 mm. FERREA valves have a 6.55 mm stem and a 109.7 mm length, SUPERTECH valves 6.54 mm and 109.6 mm.

Valve fitting

When refitting the springs, check that the collets fit the groove of the chosen valve, and replace any that are marked.

A 30.5 mm head sits on the exhaust seats at their factory size; a 31.5 mm head requires the 8 seats to be machined by the workshop.

FERREA and SUPERTECH valves differ by 0.1 mm in length: one set of 8 is fitted from a single brand.

Technical guide

Our brands

	SUPERTECH Performance, based in California, has made competition valves and valvetrain parts for more than thirty years. For the 4G63 it offers black nitrided stainless steel and Inconel at standard size and +1 mm, plus a sodium filled Nimonic version at +1 mm.
	FERREA, founded in 1978, makes its valves in Florida and Argentina. On the 4G63 it offers the Competition Plus in Super Alloy and the 6000 series in special alloy, each at standard size and +1 mm.

How to choose

Two criteria separate the nine versions, size and material:

When reinforced valves become necessary

• Raised boost or bigger turbo (Inconel or Super Alloy version recommended)
• Higher lift camshafts
• Rally, track or hill climb
• Cylinder head rebuild with burnt or distorted exhaust valves

Vehicle compatibility

OEM part number (exhaust valve):

Don't forget the inlet valves

With the 4G63 cylinder head off, take the opportunity to replace the inlet valves and the valve stem seals as well.