The Porsche M97.77 Petrol is a 3,800 cc, water‑cooled flat‑six engine produced between 2006 and 2009. It featured a dual overhead cam (DOHC) per bank layout and Bosch Motronic ME7.8 electronic fuel injection, delivering 415 PS (305 kW) with 420 Nm of torque. The horizontally opposed cylinder design ensures a low centre of gravity—critical for the 911 (997) GT3 and GT3 RS’s track-focused handling and high-revving precision.
Fitted exclusively to the Porsche 911 (997) GT3 and GT3 RS variants, the M97.77 was engineered as a motorsport-derived evolution of the M97 lineage, emphasizing high-RPM stability, instantaneous throttle response, and mechanical durability under sustained track loads. Emissions compliance in European markets was achieved through three-way catalytic converters and oxygen sensor feedback, allowing adherence to Euro 4 standards from launch.
One documented concern is cylinder bore scoring in early production units, highlighted in Porsche Technical Bulletin PTB/07/13. This issue stems from marginal Nikasil coating adhesion under thermal stress during aggressive cold-start operation. In mid-2007, Porsche transitioned to an optimized bore surface treatment to improve resistance to piston scuffing in high-load environments.
All models (2006–2009) meet Euro 4 emissions standards in European markets (KBA Type Approval #KBA/997/3381).
The Porsche M97.77 Petrol is a 3,800 cc water‑cooled flat‑six engineered for high-revving track-capable sports coupes (2006–2009). It combines Bosch Motronic ME7.8 electronic fuel injection with a DOHC 24-valve architecture and individual throttle bodies to deliver linear power, strong mid-range torque, and an 8,400 rpm redline. Designed to meet Euro 4 emissions from launch, it represents the pinnacle of the 997 GT3 engine family.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 3,800 cc | |
| Fuel type | Petrol (Unleaded) | |
| Configuration | Flat‑6, DOHC per bank, 24‑valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 102.0 mm × 78.0 mm | |
| Power output | 415 PS (305 kW) | |
| Torque | 420 Nm @ 6,250 rpm | |
| Fuel system | Bosch Motronic ME7.8 with individual throttle bodies | |
| Emissions standard | Euro 4 | |
| Compression ratio | 12.0:1 | |
| Cooling system | Water‑cooled (dual radiators with thermostatic control) | |
| Turbocharger | None | |
| Timing system | Chain‑driven DOHC with intermediate shaft (IMS) | |
| Oil type | 10W‑60 semi‑synthetic (Porsche A40 spec) | |
| Dry weight | 172 kg |
The DOHC water-cooled flat-six delivers exceptional high-RPM performance ideal for track use but requires disciplined warm-up and oil management to prevent bore scoring. Full warm-up (oil temp ≥90°C) is essential before sustained high-load use, especially in ambient temperatures below 10°C. Use of 10W-60 semi-synthetic oil meeting Porsche A40 spec is critical—modern low-viscosity oils are unsuitable. The ME7.8 system with individual throttle bodies requires precise synchronization via Porsche diagnostics. Early 2006–mid-2007 engines use standard Nikasil bores; late 2007–2009 units use optimized bore surface treatment per Porsche bulletin PTB/07/13.
Oil Specs: Requires 10W-60 semi-synthetic oil meeting Porsche A40 specification (Porsche Tech Bulletin PTB/07/13). ACEA A3/B3 oils are insufficient for high-thermal-load applications.
Emissions: All M97.77 variants meet Euro 4 standards across all production years (2006–2009) as confirmed by KBA Type Approval #KBA/997/3381.
Power Ratings: Measured under DIN 70020 standards. Output requires 98 RON fuel and optimal catalytic converter function (Porsche TIS Doc. P997‑08B).
Porsche Technical Information System (TIS): Docs P997‑06A, P997‑06C, P997‑08B
KBA Type Approval Database (KBA/997/3381)
DIN 70020 Engine Power Measurement Standard
The Porsche M97.77 Petrol was used exclusively in Porsche's 911 (997) GT3 platform with rear‑engine longitudinal mounting and no external licensing. This engine powered the 997 GT3 and GT3 RS and received a critical bore surface treatment update in mid-2007, creating a service distinction for engine rebuilds. All adaptations are documented in OEM technical bulletins.
Engine code is stamped on the rear of the crankcase near the flywheel housing (Porsche TIS P997‑06A). The 7th–8th VIN digits are '99' for all 997 models; the 10th digit indicates model year. The M97.77 can be distinguished from base 997 engines by red cam covers, individual throttle bodies, and dry-sump oil system. Early 2006–mid-2007 engines (VIN '6' and early '7') use standard Nikasil bores; late 2007–2009 (VIN '7' late, '8', '9') use optimized bore treatment. Engine serial number prefix '697.77' confirms displacement and variant.
The M97.77 Petrol's primary reliability risk is cylinder bore scoring in early 2006–mid-2007 units, with elevated incidence in track-day or aggressive road use without proper warm-up. Porsche internal durability reports from 2008 noted a significant share of early 997 GT3 engines requiring bore rework before 50,000 km under track use, while KBA field data cited bore wear as a leading cause of warranty claims in 2006–2007 production. Cold starts and lean mixture conditions exacerbate scoring, making warm-up discipline and mixture control critical.
Analysis derived from Porsche technical bulletins (2006–2009) and Kraftfahrt-Bundesamt (KBA) failure statistics (2007–2015). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about PORSCHE M-97-77.
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