Documented forum build · 993 · air-cooled
1996 993 Carrera 2 3.8 rebuild
A broken-rod rebuild developed into a high-compression 3.8-litre 993 engine using a GT3 crankshaft, custom rods and several camshaft iterations.
Evidence: Failure cause · Detailed engine specification · Assembly complete and rolling-road run-in · Reported result and road test
- Vehicle
- 1996 Porsche 993 Carrera 2
- Engine
- 993 Carrera 2 3.6-litre flat six → High-compression 3.8-litre 993 flat six with GT3 crankshaft and mechanical valve train
- Forum
- 911UK
- Thread author
- 786345jg · 23 March 2013
Vehicle and engine evidence: Opening post · Reported result and road test · Detailed engine specification
What the project aimed to do
Build a stronger weekend and track engine while retaining civilised road behaviour.
Source: Opening post · Detailed engine specification
Who did what
The owner documented the decisions and results; RPM Technik assembled the engine and BS Motorsport handled run-in and rolling-road calibration.
Source: Assembly complete and rolling-road run-in · Reported result and road test
Black C2 used for weekend road driving and occasional track use.
Vehicle context: Opening post · Reported result and road test
Documented sequence
Damage assessment
The opening posts identify the broken connecting rod and damaged crankshaft as the reason for the rebuild.
Source: Opening post · Failure cause
3.8 specification
The project adopted a GT3 crankshaft, Mahle Motorsport 3.8 piston-and-cylinder set and custom connecting rods, with the detailed configuration recorded later in the thread.
Source: Detailed engine specification
Assembly, run-in and calibration
RPM Technik completed assembly before BS Motorsport ran in and calibrated the engine on a rolling road.
Camshaft revision and road test
After initial results fell short of the target, the cams and valve actuation were revised; the author then reported the final road character and provisional output.
Source: Reported result and road test
Named components and work
Crankshaft and rods
GT3 crankshaft with a pulley-pin adaptation and custom lightweight Arrow connecting rods selected for the GT3 journal diameter.
Source: Detailed engine specification
Pistons and cylinders
Mahle Motorsport 3.8 slip-in piston-and-cylinder set with a compression ratio described by the author as above 12:1.
Source: Detailed engine specification
Final valve-train configuration
After several camshaft trials, the final setup is described with BS Motorsport RS-type cams and mechanical/964-style valve actuation.
Source: Detailed engine specification · Reported result and road test
Driveline and exhaust
New clutch, retained dual-mass flywheel and an RSR exhaust are named in the project specification.
Source: Detailed engine specification
Reported outcomes
Owner-reported power
Just under 300 hp
The author had not posted the final dyno sheet, so the wording remains deliberately approximate.
Source: Reported result and road test
Owner-estimated torque
More than 270 lb-ft
This is the author's estimate, not a transcribed measured value from a published graph.
Source: Reported result and road test
Road impression
Strong pull from about 3,000 rpm
The author reported using 6,000–6,500 rpm and completing a trip to Geneva after the rebuild.
Source: Reported result and road test
Evidence limits
- No final dyno sheet is present in the reviewed thread, so power and torque remain approximate author statements.
- The build involved professional workshops and is not a complete do-it-yourself procedure.
- Compression, performance and road impressions were not independently verified.
Access note: The thread and cited posts were publicly readable; an account is needed only to reply.
Reviewed source trail
- Complete 911UK thread · reviewed 2026-08-23
- Opening post · reviewed 2026-08-23
- Failure cause · reviewed 2026-08-23
- Detailed engine specification · reviewed 2026-08-23
- Assembly complete and rolling-road run-in · reviewed 2026-08-23
- Reported result and road test · reviewed 2026-08-23