Documented forum build · 901 / O-Series · air-cooled
1971 911E 2.2 rebuild
A matching-number 2.2-litre road-engine rebuild that retained E cams and MFI while adding 2.2S pistons and cylinders, documented from failure diagnosis through rolling-road setup.
Evidence: Cause and initial strip · Machining and assembly · First startup and rolling-road work · Final specification and reported results
- Vehicle
- 1971 Porsche 911E 2.2
- Engine
- Matching-number 2.2-litre 911E flat six → 2.2-litre flat six with 2.2S pistons and cylinders, E cams and enlarged MFI induction
- Forum
- DDK-Online
- Thread author
- 58A - 71E (James) · 24 March 2008
Vehicle and engine evidence: Complete DDK-Online thread · Machining and assembly · Final specification and reported results
Why it came apart
An intermediate-shaft gear failure led to intake-valve and piston contact. Inspection also found bearing, valve-train and piston-and-cylinder wear.
Source: Cause and initial strip
What the project aimed to do
Restore a reliable, period-looking road engine with a moderate performance increase rather than turn it into a race-only specification.
Source: Complete DDK-Online thread
Who did what
The owner documented the project; Mike Bainbridge / MBEngineering carried out specialist engine work and Bob Watson's rolling road was used for setup.
Source: Complete DDK-Online thread · First startup and rolling-road work
Matching-number road car described by the author as a fast-road and daily-use project.
Vehicle context: Complete DDK-Online thread
Documented sequence
Failure diagnosis and strip
The thread records the failed intermediate-shaft gear, valve contact and the measurements that placed crank and connecting-rod bearings outside tolerance.
Source: Cause and initial strip
Machining and assembly
The standard/standard crank was checked, the cylinder heads and MFI induction were rebuilt, deck height and piston-to-valve clearance were checked, and the cams were timed at the author's reported 3.15 mm setting.
Source: Machining and assembly
Startup and setup
After first startup the car went to a rolling road, where throttle opening and fuel settings were corrected over successive runs.
Source: First startup and rolling-road work · Final specification and reported results
Early road follow-up
At roughly 250 miles the engine was checked, minor leaks were corrected and the author reported it running well without further leakage.
Named components and work
Rotating assembly and oiling
Checked standard/standard crankshaft, NOS connecting rods, four-rib oil pump, oil-bypass modification, continuous chains and new intermediate-shaft bearings and gears.
Source: Machining and assembly · Final specification and reported results
Pistons, cylinders and valve train
2.2S pistons and cylinders, rebuilt heads, E cams, renewed valves and guides, and repaired or replaced rockers and related valve-train parts.
Source: Machining and assembly · Final specification and reported results
MFI induction
The MFI throttles and ports were enlarged from the reported 32 mm to 36 mm and the injection system was refurbished and calibrated.
Source: Machining and assembly · First startup and rolling-road work
Reported outcomes
Owner-reported peak power
177 bhp at 6,320 rpm
Final rolling-road figure reported after earlier runs of 156 and 168 bhp. The thread does not state the correction standard or whether the figure is at the wheels or crankshaft.
Source: First startup and rolling-road work · Final specification and reported results
Owner-reported peak torque
196 Nm at 6,190 rpm
Published by the author with the final setup summary; measurement basis is not independently documented.
Road follow-up
About 250 miles
The author reported a post-run-in check, corrected small leaks and good operation at that point.
Evidence limits
- Power, torque and road results are the thread author's reports and were not independently verified.
- The rolling-road correction standard and wheel-versus-crank measurement basis are not stated.
- The thread is a project record, not a complete assembly procedure or safety specification.
Access note: The complete thread and cited posts were publicly readable without an account when reviewed.
Reviewed source trail
- Complete DDK-Online thread · reviewed 2026-08-23
- Cause and initial strip · reviewed 2026-08-23
- Machining and assembly · reviewed 2026-08-23
- First startup and rolling-road work · reviewed 2026-08-23
- Final specification and reported results · reviewed 2026-08-23