🏷️ Basic Information

Make:

Porsche

Model:

928

Model Variants Covered:

928 S4, 928 GT, 928 GTS

Model Years Covered:

1990, 1991, 1992, 1993

👋 Introduction

Segment:

Front-engine, rear-wheel-drive Grand Tourer (GT)

Competitors:

Ferrari 412, Aston Martin Virage, BMW 8 Series (E31), Mercedes-Benz SEC models

Design Philosophy:

Four-seater sports car with a powerful V8 engine, transaxle layout for weight distribution, and a distinctive aerodynamic design.

Performance Focus:

High-speed cruising, comfort, and engaging driving dynamics.

📋 Manual Details

Primary Focus:

Technical Specifications

Type:

Technical Specifications Manual / Data Sheet Compilation

Language:

English

Format:

Likely PDF or Digital Download (based on typical sales offerings)

📖 Manual Coverage

Powertrain:

Engine (V8), Fuel System, Ignition System, Exhaust System

Drivetrain:

Transmission (Automatic, Manual - GT/GTS), Drive Axles, Differential

Chassis:

Suspension (Front/Rear), Steering System, Braking System, Wheels and Tires

Electrical:

Ignition, Charging System, Lighting, Instrumentation, ECU/DME, Comfort Systems

Body:

Body Structures, Exterior Components, Interior Trim (specifications focused)

Diagnostics:

Troubleshooting Charts (likely based on symptom/component), Diagnostic Codes (if applicable to spec sheets)

Maintenance:

Fluid Specifications, Lubrication Points, Basic Adjustment Data

Repair:

Torque Specifications, Component Tolerances, General Assembly/Disassembly Data

Depth:

Comprehensive technical data and specifications for diagnostic, maintenance, and repair purposes. Assumed to go beyond basic owner's manual information.

Diagnostic Tools:

May include information on specific diagnostic connectors and basic troubleshooting procedures, but likely not full OBD-II level diagnostics as the era predates widespread adoption.

📊 Manual Specifications

File Type:

Digital (PDF assumed), potentially searchable text

Quality:

High-resolution digital images/diagrams for clarity (typical for technical manuals)

Binding:

N/A (Digital)

Paper:

N/A (Digital)

Coverage Scope:

Focused on technical data and specifications for the specified model variants, likely compiled from official Porsche technical documentation.

Origin:

Likely compiled from official Porsche workshop manuals, technical bulletins, and owner information for the specified period.

⚙️ Engine Specifications

Engine Code:

M64/01 (928 S4), M64/01 (928 GT), M64/01 (928 GTS - internally revised)

Configuration:

V8, 32-valve, SOHC (early S4) / DOHC (GT/GTS)

Displacement:

5.0 L (4957 cc)

Horsepower S4:

316 hp @ 6000 rpm

Torque S4:

317 lb-ft @ 4800 rpm

Horsepower Gt:

326 hp @ 6000 rpm

Torque Gt:

317 lb-ft @ 4800 rpm

Horsepower Gts:

345 hp @ 6200 rpm

Torque Gts:

362 lb-ft @ 4800 rpm

Injection:

Bosch LH Jetronic Fuel Injection

Fuel Type:

Premium Unleaded Gasoline (91+ Octane)

Type:

Water-cooled, front-mounted radiator

Fans:

Dual electric cooling fans

Oil Capacity:

Approx. 10.5 Quarts (10 Liters)

Valvetrain:

DOHC (Double Overhead Camshafts) on GT/GTS, SOHC (Single Overhead Camshafts) on S4

🔧 Transmission

Type S4:

4-speed Automatic (Tiptronic optional)

Type Gt Gts:

5-speed Manual (G50/10 for GT, G50/12 for GTS)

Transaxle:

Rear-mounted transaxle for optimal weight distribution

Automatic Transmission Fluid:

Porsche ATF (e.g., G 002 500) or equivalent specification

Manual Transmission Fluid:

Hypoid Gear Oil SAE 75W/90 (e.g., Mobilube HD 75W-90 or equivalent)

📐 Dimensions

Length:

Approx. 4650 mm (183.1 in)

Width:

Approx. 1820 mm (71.7 in)

Height:

Approx. 1300 mm (51.2 in)

Wheelbase:

Approx. 2500 mm (98.4 in)

Curb Weight:

Approx. 1650-1750 kg (3638-3858 lbs) depending on model and options

Bolt Pattern:

5x130mm

Tire Sizes Front:

225/50 VR 16 (S4/GT), 245/40 ZR 18 (GTS)

Tire Sizes Rear:

245/45 VR 16 (S4/GT), 275/35 ZR 18 (GTS)

🛡️ Safety Features

Crash Testing:

N/A (Retroactively tested, generally performed well for its era)

Braking System:

4-wheel Anti-lock Braking System (ABS)

Suspension:

Optional: Porsche Active Suspension Management (PASM) not applicable; Dynamic Ride Control (DRC) not applicable; but advanced independent suspension for stability.

Airbags:

Driver and passenger airbags standard on later models

Seatbelts:

3-point inertia-reel seatbelts

Chassis Design:

Reinforced safety cage, crumple zones

💡 Technology Features

Audio System:

Bose premium sound system (optional), Porsche CR-210 cassette/radio unit

Climate Control:

Automatic Climate Control (ACC)

Cruise Control:

Standard

Headlights:

Aerodynamic Headlights with integrated fog lamps

Portability:

N/A (Era-appropriate technology, no modern smartphone integration)

🔧 Maintenance

Oil Change:

Every 12,000 miles or 12 months

Major Service:

Timing Belt: Every 30,000 miles or 3 years (critical maintenance item for interference engine)

Brake Fluid:

Every 2 years

Coolant:

Porsche High-Performance Coolant (G 002 000) or equivalent 50/50 mix

Power Steering Fluid:

Pentosin CHF 11S or equivalent hydraulic fluid

Common Problems:

Timing belt failure (catastrophic engine damage), cooling system leaks (hoses, radiators, water pump), fuel pump and line degradation, electrical gremlins (especially older wiring and connectors), differential seals, clutch wear (manual).

Preventative Measures:

Strict adherence to timing belt replacement intervals, regular inspection of cooling system components, proactive replacement of aging fuel lines and electrical connectors.

📚 Vehicle History

Brand Focus:

High-performance sports cars and luxury grand tourers.

Introduction Year:

1977

Design Change:

The 1990-1993 models represent the final evolution of the 928, with the S4 receiving significant updates, followed by the more powerful GT and GTS variants.

Production Period:

1977-1995

Manufacturing Location:

Stuttgart, Germany

🏆 Awards & Recognition

Historical Acclaim:

While specific awards for the 1990-1993 variants are less documented than earlier models, the 928 series as a whole was recognized for its engineering, comfort, and performance as a luxury GT.