Techincal & Facts
The Porsche 928 – Detailed engine specs & Performance figures
Here’s a comprehensive summary of the engines utilised in the Porsche 928 throughout its production run (1977‑1995) — including their technical specifications, changes over the years, and performance metrics.
Overview
The Porsche 928 was powered throughout its life by various naturally‑aspirated V8 engines. Displacements evolved from ~4.5 L up to about 5.4 L. The valvetrain architecture began with SOHC (single overhead cam per bank) with 2 valves per cylinder, then moved to DOHC 4‑valve per cylinder in the later “S4”, “GT”, “GTS” versions. Bore, stroke, compression, and power output increased over time.
Below are the main engine variants, roughly in chronological order, with their specs and performance.
Engine Variants & Specs
| 4.5 V8 (M28 / early 928) | 1977‑1982 (928, early) | 4,474 cc (≈4.5 L), Bore × Stroke ≈ 95.0 mm × 78.9 mm (encyCARpedia) | SOHC, 2 valves per cylinder (16 total) (encyCARpedia) | ~8.5:1 (encyCARpedia) | ≈ 237 bhp (≈240 PS) at ~5,500 rpm (encyCARpedia) | ≈ 258 lb‑ft (≈ 350 Nm) at ~3,600 rpm (encyCARpedia) | 0‑62 mph ~7.2 s; top speed ~143 mph (≈230‑240 km/h) (encyCARpedia) |
| 4.7‑litre “S” versions | Early 1980s onwards (928 S) | Slightly larger bore; e.g. 4.7 L versions around 4,664 cc (≈97.0 mm bore × same stroke) (Wikipedia) | Still SOHC, 2 valves per cylinder in many markets for that version (Wikipedia) | Compression higher than early; some versions ~10.0‑10.4:1 in later 4.7s (Wikipedia) | ~300‑310 PS (≈ 306‑310 hp) in the 4.7 S versions, depending on market and year; for example, a 4.7 S V8 rated at 310 hp @ 5,900 rpm (Auto Data) | Torque ~385‑400 Nm in many versions; exact rpm varies (≈4,000‑4,500 rpm) (Wikipedia) | 0‑100 km/h (0‑62 mph) ~6.2 s in some 4.7 S versions; top speeds rising above 150 mph in some markets. (Auto Data) |
| 5.0‑litre versions (transition to more power / emissions compliance) | Mid‑1980s (S, S4, etc.) | Displacement ≈ 4,957 cc (≈5.0 L), Bore increased to ~100.0 mm, same stroke (~78.9 mm) in many; later versions 5.4 L (Wikipedia) | Some early 5.0s still SOHC/2 valves; later ones DOHC/4 valves per cylinder (S4 etc.) (Wikipedia) | Compression around 9.3‑10.4:1 in many markets, depending on emissions etc. (Wikipedia) | Power varied: e.g. 5.0 GT version ~330 PS (≈ 325‑330 hp) @ ~6,200 rpm in some versions (encyCARpedia) | Torque ~430 Nm @ ~4,100‑4,200 rpm in those 5.0 GT versions (encyCARpedia) | 0‑62 mph ~5.8 s; top speed around 170‑171 mph in GT versions. (encyCARpedia) |
| 5.4‑litre GTS | Early 1990s (928 GTS, 1992‑1995) | Displacement ~5,397 cc (≈5.4 L); bore × stroke often ~100.0 mm × ~85.9 mm in GTS versions (Wikipedia) | DOHC, 4 valves per cylinder in GTS (full high performance) (Wikipedia) | Compression ratio in the GTS ~10.4:1 in many markets. (Wikipedia) | Peak Power ~345 PS (≈ 345 bhp) @ ~5,700 rpm in GTS models (encyCARpedia) | Torque ~369 lb-ft (≈ 500 Nm in metric) @ ~4,250 rpm in the GTS (encyCARpedia) | 0‑62 mph ~5.7 s; top speed ~171 mph; better power/torque curve due to newer induction, better breathing (valves etc.) (encyCARpedia) |
* Compression ratios varied by market (due to emissions, fuel quality etc.), so those listed are typical or from certain versions.
Other Technical/Mechanical Details
- Engine layout & positioning: Front longitudinally‐mounted, driving the rear wheels via a transaxle (i.e. transmission and drive to back in a torque tube), to help with weight distribution. (autoevolution)
- Valvetrain evolution:
• Early engines: SOHC with 2 valves per cylinder.
• Later performance models (S4, GT, GTS) moved to DOHC with 4 valves per cylinder, which allowed higher revs and more power. (Wikipedia) - Bore‑stroke changes: The stroke (≈78.9 mm) remained largely consistent in many versions; bore increased over time to raise displacement. The GTS also increased stroke slightly (≈85.9 mm in some versions) for the biggest displacement. (Wikipedia)
- Emissions / fuel systems: Over time, fuel injection and ignition systems became more advanced. Early mechanical/electronic systems in SOHC models; later Bosch LH‑Jetronic, EZF ignition, catalytic converters etc. (Wikipedia)
- Weights: The 928s typically weighed between ~1,450 kg to ~1,620 kg depending on model, equipment, drivetrain. GTS versions are among the heavier due to larger engines, extra equipment. (encyCARpedia)
Performance Figures Over Time
As the engines developed, the 928’s performance improved in terms of acceleration, top speed, and torque, especially in the S, GT, GTS models. To illustrate:
- Early 4.5 L versions: ~7.0‑7.2 seconds 0‑62 mph; top speed ~143 mph. (encyCARpedia)
- Mid‑life 4.7 S: faster 0‑100 km/h (~6.2 s) and higher top speeds (≈ 255 km/h / ~158‑160 mph) in some European/“unrestricted” versions. (Auto Data)
- Later 5.0 GT / S4 etc: 0‑62 mph ~5.8 s; top speeds creeping toward ~170‑171 mph. (encyCARpedia)
- Final GTS: best acceleration (~5.7 seconds for 0‑62 mph); peak speeds in line with ~171 mph; stronger torque and power through the rev range. (encyCARpedia)
Summary: Key Engine Codes / Stages
Below is a simplified map of how the main engine stages compare:
| Stage | Approx Years | Displacement | Cam / Valves | Approx Power / Torque | Key Upgrades from Previous |
|---|---|---|---|---|---|
| Base 4.5 L SOHC | 1977‑early 1980s | 4.5 L | SOHC / 2‑vpc | ~237‑240 bhp; ~350 Nm | First 928, solid GT performance |
| 4.7 “S” | early‑mid 80s | ~4.7 L | still many SOHC versions | ~300‑310 PS / ~385‑400 Nm | Bore increase, higher compression, better fuel/ignition to meet emissions and improve power |
| 5.0 / transition to 4‑valve | mid‑80s | ~5.0 L (4.957 cc) | Begin DOHC / 4‑valve in performance versions | ~325‑330 PS; 430 Nm | More rev capability; better breathing; better torque at higher rpm |
| GTS 5.4 L | 1992‑1995 | ~5.4 L (≈ 5,397 cc) | DOHC / 4‑valve | ~345 PS; ~500 Nm | Peak output; highest engineering in the 928 line; best acceleration & high speed |
