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2.5L 8v - M44
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2.5L 8v - M44
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Set of 4 reinforced inlet valves for PORSCHE 924 S, 944 2.5 and 944 Turbo.
The M44 is Porsche's 2.5 litre inline four with 8 valves and a single overhead camshaft. It powers the 924 S (150 then 160 hp), the 944 2.5 (150 to 163 hp) and the 944 Turbo (220 then 250 hp), from 1981 to 1991.
Its cylinder head has only 4 inlet valves, one per cylinder. On the 944 Turbo the original valve 951.105.415.00 has a 45 mm head, a 9 mm stem and a 111.5 mm length. Higher boost, a sharper camshaft or track use put more heat and harder seat impacts on it.
The inlet valve lets the fresh charge in, strikes its seat at every closing and slides constantly in its guide, at 400 to 550 °C. At that level an ordinary chrome-silicon steel falls from 500 MPa at 500 °C to 250 MPa at 600 °C: 50 % less strength.
FERREA's Competition Plus is a stainless steel designed for heat, with a chrome-plated stem that rubs less in the guide. Against a conventional valve, the maker quotes 20 % more hot and fatigue strength and a seat that lasts 25 % longer.
The F2299P takes the head to 46 mm, 1 mm more than the original 944 Turbo valve: the passage at the seat widens, each cylinder fills better and the engine gains power, provided the 4 inlet seats are machined to that diameter.
| Part number | Brand | Size | Head Ø OEM 45 mm | Stem Ø OEM 9 mm | Length | Grooves | Material |
|---|---|---|---|---|---|---|---|
| F2299P*4 | FERREA | +1 mm | 46 mm | 8.98 mm | 111.6 mm | 3 | Stainless steel, chrome-plated stem |
F2299P is +1 mm: 46 mm head, 8.98 mm stem, 111.6 mm length, 3 grooves.
| Part | PORSCHE original | Reinforced |
|---|---|---|
| Collets | ||
| Valve stem seals | 951.104.195.01 (944 Turbo) | |
| Valve guide | 928 104 328 02 (924 S, 944 2.5) |
The valve has 3 grooves: on reassembly, check that the collets bear properly in all 3 grooves and replace any that are worn.
With its 46 mm head, the F2299P requires the 4 inlet seats to be machined to that diameter before lapping.
 | Set up in 1978, FERREA designs and makes competition valves in its Florida and Argentina plants. Its Competition Plus range combines a heat-resistant stainless steel with a chrome-plated stem, for prepared road and race cylinder heads. |
A groove is the notch in the stem that holds the collets. A single valve is offered for this engine:
| Criterion | Option 1 | Option 2 |
|---|---|---|
| Size | +1 mm, 46 mm 10 to 12 cfm more per mm of head, seats machined; also recovers reground seats. F2299P*4. | |
| Grooves | 3 grooves Original fitting, new collets advised. F2299P*4. |
| Model | Engine code | Power | Years |
|---|---|---|---|
| 924 2.5 S | M44.07 / M44.08 | 150 hp | 1985-1987 |
| 924 2.5 S | M44.09 / M44.10 | 160 hp | 1987-1988 |
| 944 2.5 | M44.01 / M44.03 / M44.05 / M44.06 | 163 hp | 1981-1987 |
| 944 2.5 | M44.02 / M44.04 / M44.07 / M44.08 | 150 hp | 1985-1987 |
| 944 2.5 | M44.05 / M44.09 / M44.10 | 160 hp | 1987-1990 |
| 944 2.5 Turbo | M44.50 / M44.51 | 220 hp | 1985-1988 |
| 944 2.5 Turbo | M44.52 | 250 hp | 1987-1991 |
| 944 Cabriolet 2.5 Turbo | M44.52 | 250 hp | 1990-1991 |
OEM part number (inlet valve): 951.105.415.00 (944 Turbo)
With the M44 cylinder head off, replace its 4 exhaust valves as well:
| PORSCHE 924 S 944 2.5 M44 exhaust valves → |
