Alternator 12v 55A Porsche 911 1965-73 (Internal Regulator)  ❭  91160311800

Alternator 12V 75A – Internal Regulator

Restore dependable charging performance with this OEM Supplier 12V 75A Alternator, equipped with an internal voltage regulator. Manufactured by an Original Equipment supplier, this alternator is produced to the same demanding standards as the component originally fitted by Porsche, providing the quality, reliability and fitment expected from factory-specification electrical components.

Fits:

• Porsche 911 1978-1983 3.0L / SC
• Porsche 911 1975-1977 3.0L Turbo (930)
• Porsche 911 1978-1983 3.3L Turbo (930) 

The alternator is one of the most important components of the vehicle's electrical system. While the engine is running, it generates electricity to power essential systems including the ignition, lighting, fuel injection, instruments, heating and ventilation controls, whilst simultaneously recharging the battery. A failing alternator can quickly lead to a discharged battery, poor engine performance and complete electrical failure.

This unit is manufactured for precise fitment and dependable long-term operation, making it an ideal replacement for worn or failed original alternators during routine maintenance or restoration.

What Does the Alternator Do?

The alternator converts mechanical energy from the engine into electrical energy.

Its primary functions include:

• Charging the vehicle battery.
• Supplying electrical power whilst the engine is running.
• Maintaining a stable charging voltage.
• Supporting ignition and fuel systems.
• Powering lighting and electrical accessories.
• Preventing battery discharge during normal driving.

The internal voltage regulator continuously controls the alternator output, ensuring the battery and electrical components receive the correct charging voltage without overcharging.

Why Replace the Alternator?

Alternators are subjected to constant heat, vibration and high rotational speeds throughout their service life.

Common causes of failure include:

• Worn bearings.
• Failed internal voltage regulator.
• Worn brushes.
• Damaged slip rings.
• Internal winding faults.
• Diode pack failure.
• Corrosion.
• Age-related wear.

Replacing a worn alternator restores reliable charging performance and helps prevent unexpected breakdowns.

Symptoms of a Failing Alternator

Common signs include:

• Battery warning light illuminated.
• Battery repeatedly going flat.
• Slow engine cranking.
• Dim or flickering headlights.
• Unstable voltage.
• Electrical accessories operating poorly.
• Intermittent charging.
• Bearing noise from the alternator.
• Burning electrical smell in severe cases.

Ignoring these symptoms can eventually leave the vehicle unable to start once the battery becomes fully discharged.

Important Installation Information

This alternator is suitable for Porsche 911 models (1978-1983) using an internal voltage regulator.

For Porsche 911 turbo 3.0ltr (1975-1977) applications, the following additional components are required:

• Resistor 91164198100 × 1
  
• Air Deflector 91110603305 × 1
  
• Cable Connector 111971511 × 2       

Voltage: 12V
Power: 75 Amp.
Direction of rotation: Clockwise (CW)
Attachment: 6 bolts, Radius 135 mm
Controller: internal
Pulley: no

Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.

91160312004

The product you are viewing cross references to these numbers

12 Volt 90 Amp Alternator 

The Porsche Alternator is a high-quality 12 Volt 90 Amp charging system component designed for Porsche 911 and Porsche 911 turbo models. As one of the most important electrical components on the vehicle, the alternator generates electrical power while the engine is running and continuously recharges the battery to maintain reliable operation of the vehicle's electrical systems.

Fits:

• Porsche 911 1984-1986 3.2L
• Porsche 911 1987-1989 3.2L G50
• Porsche 911 1978-1989 3.3L Turbo (930)

From powering the ignition system and fuel delivery components to supporting lighting, instrumentation, heating and other electrical accessories, the alternator plays a crucial role in the day-to-day reliability and performance of your Porsche. Without a properly functioning alternator, the battery will gradually discharge, leading to starting difficulties, electrical faults and eventually complete vehicle shutdown.

Overall length: 173mm
Voltage: 12V
Power: 90Amp
Direction of rotation: clockwise (CW)
Fixing: 6 studs
Controller: internal
Pulley: not supplied

Whether you're maintaining an air-cooled Porsche 911, servicing a Porsche 911 turbo or carrying out a restoration project, replacing a worn alternator helps ensure dependable performance and protects the vehicle's electrical system.

What Does an Alternator Do?

The alternator converts mechanical energy generated by the engine into electrical energy. Driven by the engine belt system, it supplies power to the vehicle while simultaneously charging the battery.

The alternator is responsible for:

Recharging the battery while driving Powering electrical systems and accessories Maintaining stable system voltage Supporting ignition and fuel system operation Ensuring reliable starting performance

A healthy alternator is essential for keeping every electrical system operating correctly.

Symptoms of Alternator Wear or Failure

Alternators operate continuously whenever the engine is running and are subjected to heat, vibration and electrical load. Over time, internal components such as bearings, brushes, voltage regulators and diodes can wear or fail.

Common symptoms of alternator failure include:

Battery warning light illuminated Repeated flat batteries Slow or difficult engine starting Flickering headlights Dimming dashboard lights Electrical accessories operating intermittently Low charging voltage Unusual whining or grinding noises Burning electrical smell Vehicle stalling due to insufficient voltage

In many cases, alternator failure develops gradually before progressing to complete charging system failure.

Why Alternator Replacement Matters

A faulty alternator can leave the battery unable to recharge properly, eventually causing loss of electrical power and unexpected breakdowns.

Replacing a worn alternator helps:

Restore correct battery charging Improve electrical system reliability Prevent roadside breakdowns Maintain stable voltage output Extend battery life Protect sensitive electrical components Eliminate charging system warning lights Improve overall vehicle dependability

For classic and performance Porsche models, maintaining a healthy charging system is essential for reliable operation and long-term ownership enjoyment.

Features & Benefits

• 12 Volt, 90 Amp output
• Provides reliable battery charging
• Maintains stable electrical system voltage
• Supports ignition and fuel system operation
• Durable construction for long service life
• Ideal for maintenance, repairs and restoration projects       

Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.

91160312005

The product you are viewing cross references to these numbers

Alternator Ground Strap.

Fits:
Porsche 911 1978-89

Diagram ref no 18

Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.

91161223300

The product you are viewing cross references to these numbers