Engine Performance Kit (Not For USA Vehicles)

Foreword
The article describes a performance kit for the 911 Carrera (996). A characteristic of the new engine is its continuous power development, particularly at higher engine speeds above 5,000 rpm. The only changes are modifications to the engine.




Technical data







Differences, items 1 - 6







Differences, items 7 - 12

Differences, details

Item 1





Pistons

The valve recesses were mechanically adjusted to provide clearance for the exhaust valves. (Arrows.)

Item 2

Camshafts

The inlet camshafts and exhaust camshafts possess a greater cam stroke.




Camshafts of cylinder bank 1 - 3
Identification on the camshaft
Inlet camshaft: 991.00 3,4 L/KIT IN 1-3
Exhaust camshaft:996.00 3,4 L/KIT IN 1-3




Camshafts of cylinder bank 4 - 6
Identification on the camshaft
Inlet camshaft: 992.00 3,4 L/KIT IN 4-6
Exhaust camshaft: 997.00 3,4 L/KIT IN 4-6

Item 3




Valve discs, valve springs
The parts distinguish the higher-performance engine from the standard engine in the area of the cylinder head:
1. Valve keys (standard part)
2. Valve disc at top
3. Valve spring on outside
4. Valve spring on inside
5. Valve seal (standard part)
6. Valve disc at bottom
7. Valve guides
8. Cylinder head
9. Valve seats
The valve seats are additionally provided with a seat surface of 60'.




Valve guides
The valve guides were shortened in the area of the inlet and outlet ducts.




Cylinder head
The cylinder heads already have a reduced height. Subsequent machining of the sealing surface is therefore not permissible.

Item 4




Valves
Depending on the time of assembly, the engines of the X51 are equipped with two different valve versions.




Valves
Version 1:
Inlet valve (standard) and exhaust valve (standard) are additionally equipped with valve caps.




Valves
Version 2: (Introduced in December '98) Inlet and exhaust valves lengthened by 1.5 mm. Valve caps were omitted after introduction of the valves (version 2). The valve caps will remain in stock as replacement parts for the shorter standard valves of the 911 Carrera (996).
Identification of inlet valve: Yellow dot on the valve disc
Identification of exhaust valve: Black dot on valve disc

Item 5




Dual-chamber suction pump
A dual-chamber suction pump, which is sealed with two sealing rings, is fitted on the cylinder head of cylinder bank 4 - 6. The M6 x 30 fastening screws (4 ea.) are fitted with Loctite 242 or 243.

Item 6




Oil suction pipe
The oil suction pipe is fitted between the dual-chamber suction pump and the cylinder head cover. The rear M6 x 40 fastening screw is fitted with Loctite 242 or 243.




Oil suction pipe
A take-up bore for the oil suction pipe was added on the cylinder head cover of cylinder bank 4 - 6.




Oil suction pipe
Oil suction pipe on cylinder head.




Shield
The shield was modified accordingly in the area of the oil suction pipe.

Item 7




Oil pan with partition box
The partition box was redesigned and consists of metal (aluminum sheetmetal). The standard parts consist of plastic.

Item 8




Gasket for exhaust manifolds
The gaskets were adapted to the larger exhaust ducts.

Item 9




Exhaust manifolds
The exhaust manifolds were also adapted to the larger exhaust ducts.

Item 10




Suction line on the A/C compressor
The suction line was modified for space reasons.

Item 11




Intake pipes
The intake pipes were adapted to the internal contours of the inlet ducts on the cylinder head.

Item 12




Intake distributors
The right and the left intake distributors have been modified and are now castings. The figure shows the completely assembled intake system.