Reinforced exhaust valves Honda Prelude H22

Honda engines covered

The H22 is the twin-cam 2.2 16V VTEC of the Honda Prelude IV and V, built from 1993 to 2001. This naturally aspirated four-cylinder has four valves per cylinder and VTEC variable valve timing.

It therefore has 8 exhaust valves, Honda part number 14721-P13-000: 30.0 mm head and 5.5 mm stem. These valves take most of the extra heat of a tuned H22.

SUPERTECH reinforced exhaust valves

Without forced induction, the head of an exhaust valve rises to between 760 and 870 °C (metal temperature); with a turbo or a supercharger it goes past 1,000 °C. It cools about 75 % through the seat and 20 % through the guide. The original steel, compared with the EV8 family, loses nearly half its strength between 600 °C (550 MPa) and 800 °C (300 MPa); beyond that the head overheats, fatigues, distorts and the seat seal is lost.

The HEVN-1006F-8 and HEVN-1007-8 are in black nitrided stainless steel, a treatment that hardens the surface and limits stem wear in the guide. The HEVI-1008-8 is in Inconel, a nickel-based superalloy that keeps 860 MPa at 732 °C and 554 MPa at 816 °C, nearly 85 % more than EV8 steel around 800 °C. FERREA's F1823P, F1958P and F1458P are made of Super Alloy, a nickel-based alloy from the Competition Plus range; the F6023 and F6058, from the 6000 series, are made of EV8 stainless steel.

The HEVN-1007-8 takes the head to 30.5 mm (+0.5 mm) and the HEVI-1008-8 to 31.0 mm (+1 mm). Burnt gases leave more easily, the next filling benefits and power increases; the exhaust seats are then machined to the chosen size. The FERREA F1958P goes to 30.5 mm, the F1458P and F6058 to 31.0 mm.

Exhaust valve technical specifications

The HEVN-1006F-8 has a flat head, in standard size.

Valve fitting

The existing collets can be reused if their profile matches the groove of the chosen SUPERTECH valve: check before reassembly.

The HEVN-1006F-8 fits the original seats; with a 30.5 or 31.0 mm head the 8 exhaust seats are recut to size.

The three SUPERTECH valves have a 5.45 mm stem and a 106.45 mm overall length; the FERREA valves a 5.48 mm stem and a 107.1 mm length.

Technical guide

Our brands

	SUPERTECH Performance, a Californian maker of racing valves and valvetrain parts for more than thirty years, offers black nitrided stainless steel for the H22 in standard size and +0.5 mm, and Inconel in +1 mm.
	FERREA, founded in 1978 by Horacio Ferrea and Daniel Urrutia, makes its valves in Florida and Argentina. For the H22, it offers its Super Alloy valve from the Competition Plus range and its 6000 series, in standard and oversize.

How to choose

The size decides the seat machining, the material the heat resistance:

When reinforced valves become necessary

• Turbo or supercharger added (Inconel version recommended)
• More aggressive camshafts or valve springs
• Frequent track use
• Cylinder head rebuild with tired exhaust valves
• Enlarged seats to improve flow

Vehicle compatibility

OEM part number (exhaust valve): 14721-P13-000

Don't forget the inlet valves

For an H22 with the cylinder head open, also think of the inlet valves and the valve stem seals.