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1.6L 16v - D16A1/D16A9
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1.6L 16v - D16A1/D16A9
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Set of 8 reinforced exhaust valves for the Honda D16A1 and D16A9.
The D16A1 and D16A9 are the twin-cam 1.6 16V engines Honda fitted in the late 1980s and early 1990s to the Civic IV, CRX II, Civic V and Concerto. These naturally aspirated four-cylinders have four valves per cylinder.
Each engine therefore has 8 exhaust valves. Honda part number 14721-PG6-000 (D16A9): 27.0 mm head, 6.6 mm stem and 104.6 mm overall length; they take the extra heat when the engine is tuned.
Without a turbo or supercharger, the head metal of an exhaust valve sits between 760 and 870 °C; forced induction takes it above 1,000 °C. About 75 % of that heat leaves through the seat and 20 % through the guide. The steel used as the original reference, from the EV8 family, holds only 300 MPa at 800 °C against 550 MPa at 600 °C; overloaded, the head fatigues, warps and no longer closes properly on its seat.
The HEVN-1005-8 is in black nitrided stainless steel: nitriding hardens the surface and reduces stem wear against the guide.
It is a +0.5 mm size, with a 27.5 mm head. A larger head lets burnt gases out faster and improves filling on the next cycle, at the cost of machining the exhaust seats to that diameter.
| Part number | Brand | Size | Head Ø | Stem Ø | Length | Grooves | Material |
|---|---|---|---|---|---|---|---|
| HEVN-1005-8 | SUPERTECH | +0.5 mm | 27.5 mm | 6.55 mm | 104.6 mm | 1 | Black nitrided stainless steel |
| Part | Honda original | Reinforced |
|---|---|---|
| Collets | 14781-PE0-003 | KPR-6.6-LS (single groove) |
| Valve stem seals | 12210-PM7-003 / 12211-PH7-003 | VS-H6.6E-8 (exhaust) |
| Valve guide | 12205-PM7-305 (OS) |
The single groove HEVN-1005-8 is fitted with KPR-6.6-LS collets.
With a 27.5 mm head, the 8 exhaust seats are recut to size before assembly.
The 6.55 mm stem is common to the 8 valves of the set.
 | SUPERTECH Performance, based in California, has been designing racing valves and valvetrain parts for more than thirty years. For the D16A1 and D16A9, it offers a black nitrided stainless steel exhaust valve in +0.5 mm size. |
A single part number is offered for these engines:
| Criterion | Option 1 | Option 2 |
|---|---|---|
| Size | +0.5 mm, 27.5 mm Seats machined to size. HEVN-1005-8. | |
| Material | Black nitrided stainless steel HEVN-1005-8. |
| Model | Engine code | Power | Years |
|---|---|---|---|
| Civic IV 1.6 i 16V (ED7) | D16A9 | 130 hp | 1987-1991 |
| Civic IV 1.6 16V 4x4 (SH4) | D16A1 / D16A9 | 107-132 hp | 1987-1992 |
| CRX II 1.6 i 16V (ED9) | D16A9 | 131 hp | 1987-1989 |
| Civic V 1.6 (EG2, SR4) | D16A9 | 131 hp | 1991-1996 |
| Concerto 1.6 (HW, MA, HWW) | D16A9 | 131 hp | 1989-1992 |
| Orthia / Partner 1.6 (EY8) | D16A1 | 105 hp | 1996-2006 |
OEM part number (exhaust valve): 14721-PG6-000 (D16A9)
An open D16A1 or D16A9 cylinder head is also the time to check the inlet valves and the valve stem seals.
| D16A9 inlet valves → |
