The Porsche 911.86 is a 3,164 cc, air‑cooled flat‑six (boxer) petrol engine produced between 1984 and 1989. It features Bosch Motronic electronic fuel injection, overhead valve (OHV) layout, and dry sump lubrication. In standard form it delivered 184 kW (250 PS) at 5,900 rpm with 290 Nm of torque at 4,800 rpm, engineered for refined performance while meeting emerging Euro 1-equivalent emissions standards.
Fitted to the Porsche 911 Carrera 3.2 (G-series) for global markets, the 911.86 was designed to enhance drivability, throttle precision, and emissions compliance over its K-Jetronic predecessor. Driving character emphasizes smooth power delivery, improved cold-start behavior, and robust mid-range torque typical of enlarged air-cooled flat-six engines.
A documented concern is wear in the camshaft follower bores under extended high-RPM use, which can lead to excessive valve lash and rough running. This issue, highlighted in Porsche Technical Bulletin PTB‑85/07, was linked to material tolerances in early 1984–1986 production units. From 1987 onward, revised heat treatment and bore surface finishing reduced incidence.
Production years 1984–1989 meet pre‑Euro national emissions standards; formal Euro classification does not apply (KBA Germany Type Approval #18456).
The Porsche 911.86 is a 3,164 cc flat‑six air‑cooled petrol engine engineered for the 911 Carrera 3.2 (1984–1989). It combines Bosch Motronic electronic fuel injection with OHV architecture to deliver improved drivability and emissions control over earlier K-Jetronic variants. Designed before formal Euro regimes, it relies on thermal efficiency and precise electronic management to meet contemporary West German type approval requirements.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 3,164 cc | |
| Fuel type | Petrol (Leaded, compatible with unleaded with upgrades) | |
| Configuration | Flat‑6 (boxer), OHV, 12‑valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 98.0 mm × 70.4 mm | |
| Power output | 184 kW (250 PS) @ 5,900 rpm | |
| Torque | 290 Nm @ 4,800 rpm | |
| Fuel system | Bosch Motronic 2.1 electronic injection | |
| Emissions standard | Pre‑Euro (national type approval only) | |
| Compression ratio | 9.5:1 | |
| Cooling system | Air‑cooled (fan‑driven) | |
| Turbocharger | None | |
| Timing system | Gear‑driven camshaft | |
| Oil type | SAE 20W-50 mineral oil (API SF/CC) | |
| Dry weight | 136 kg |
The Motronic system provides precise fuel and ignition control, enabling better cold starts and emissions compliance than K-Jetronic. However, it requires intact sensors (coolant temp, throttle position, O2) and stable electrical supply. Operation on modern unleaded fuel necessitates hardened valve seats to prevent recession. Dry-sump oil checks must be performed with the engine running. Use only non-detergent SAE 20W-50 mineral oil with ZDDP to protect cam lobes. Early 1984–1986 units are prone to cam follower bore wear; inspect valve clearances more frequently if high-RPM use is common.
Oil Specs: Requires non-detergent SAE 20W-50 mineral oil (API SF/CC) per Porsche Lubricants Guide 1984.
Emissions: Pre-Euro emissions regime; governed by KBA Germany national type approval (KBA #18456). No Euro classification applies.
Power Ratings: Measured per DIN 70020 standard. Output verified in KBA approval documentation.
Porsche Werkstatthandbuch 911 (1984)
Porsche Technical Bulletin PTB-85/07
Kraftfahrt-Bundesamt (KBA) Type Approval Database #18456
Porsche Engineering Report ER-911/86
The Porsche 911.86 was used exclusively in the Porsche 911 Carrera 3.2 (G-series) with rear-engine, longitudinal mounting. Platform-specific adaptations included revised engine mounts and updated cooling shrouds for the 3.2 L displacement. From 1987, camshaft components received improved heat treatment per PTB‑85/07, creating minor interchange limits between early and late production units. All adaptations are documented in OEM technical bulletins.
Locate the engine number stamped on the crankcase adjacent to the oil filler tube (Porsche Werkstatthandbuch 911/1984). The prefix '911/86' confirms this variant. Visual identification includes the Bosch Motronic ECU and wiring harness, air-cooled cylinder fins, and dry-sump oil tank. Differentiate from 911/67 by presence of electronic fuel injection (ECU, sensors) and slightly smaller bore (98 mm vs. 100 mm). Early units (1984–1986) may lack revised cam follower bores introduced in PTB‑85/07.
The 911.86's primary reliability risk is cam follower bore wear in early 1984–1986 production units under sustained high-RPM operation. Porsche internal quality data from 1986 noted elevated valve train noise complaints in pre-1987 builds, while KBA workshop reports identify Motronic sensor degradation as a frequent cause of drivability issues. Extended high-RPM use without oil changes accelerates cam lobe wear, making oil quality and valve clearance checks critical.
Analysis derived from Porsche technical bulletins (1984–1988) and Kraftfahrt-Bundesamt (KBA) failure statistics (1986–1990). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about PORSCHE 911-86.
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