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2.5L 8v - M44
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2.5L 8v - M44
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Set of 4 reinforced exhaust valves for the Porsche 924 S, 944 2.5 and 944 Turbo.
The 2.5 litre M44 is the Porsche four-cylinder with 8 valves and a single overhead camshaft fitted to the 924 S, the 944 2.5 and the 944 Turbo, the latter with a turbocharger.
It has 4 exhaust valves, one per cylinder, part number 928.105.410.04 on the naturally aspirated versions and 951.105.416.07 on the Turbo, both with a 40 mm head and a 9 mm stem.
On the naturally aspirated 924 S and 944, the metal of an exhaust valve head reaches 760 to 870 °C; on the 944 Turbo it goes above 1,000 °C. About 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: the head distorts, fatigues and ends up no longer sealing the seat.
FERREA offers for this engine a valve from its Competition Plus range in special alloy, with 3 grooves, quoted 20 % stronger when hot with a seat life extended by 25 %.
| Part number | Brand | Size | Head Ø | Stem Ø | Length | Grooves | Material |
|---|---|---|---|---|---|---|---|
| F2298P*4 | FERREA | Standard | 40.0 mm | 8.96 mm | 112.3 mm | 3 | Special alloy |
F2298P is standard size: 40 mm head, 8.96 mm stem, 112.3 mm length, 3 grooves.
| Part | Porsche original | Reinforced |
|---|---|---|
| Collets | ||
| Valve stem seals | ||
| Valve guide |
The valve has 3 grooves: on reassembly, check that the collets lock into these 3 grooves and replace any worn ones.
At standard size, the 4 exhaust seats are simply recut before lapping.
A cylinder head takes all 4 valves of the same part number.
 | FERREA, founded in 1978, makes its valves in Florida and Argentina. For the 8-valve 2.5 M44 it offers a Competition Plus exhaust valve in special alloy, at standard size. |
Only one version is offered for this engine:
| Criterion | Option 1 | Option 2 |
|---|---|---|
| Size | Standard, 40 mm Only FERREA version for these engines. F2298P*4. | |
| Grooves | 3 grooves 3-groove collets. F2298P*4. |
| Model | Engine code | Power | Years |
|---|---|---|---|
| 924 S 2.5 | M44.03 / M44.08 / M44.10 | 1985-1988 | |
| 944 2.5 | M44.01 to M44.10 | 1981-1991 | |
| 944 Turbo 2.5 | M44.50 / M44.51 / M44.52 | 1981-1991 |
OEM part number (exhaust valve): 928.105.410.04 (924 S, 944) ; 951.105.416.07 (944 Turbo)
An M44 cylinder head on the bench is the right time to replace the inlet valves and the valve stem seals as well.
| Inlet valves Porsche 924 S 944 2.5 M44 → |
