GT4
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- 8 Nov 2008
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The 996 X51 has an historical importance and pure engineering at its heart.
For two years this was the most powerful 4 seat or 4WD model (the Turbo had yet to be released).
Significantly, it is not just power output upgrades, having both additional cooling (centre radiator) and lubrication upgrades (high-G sump baffles, additional pump and oil lines).
Those two options are almost worth the entry ticket alone: as the 996 cylinder failures almost always involve the overheating and under lubrication of cylinder number 6, these modifications go someway to mitigating the seizures.
The 996 X51 was the sister model to the GT3 during development.
Porsche Motorsport Division parallel developed the narrow body C2 with C4 strengthened front chassis/body structure, track suspension and roll cage and even the aerodynamic Cup AeroKit (note: its note even officially called the GT3 kit), but with different engines.
The GT3 3.6 (M96/76) and X51 PowerKit 3.4 M96/01S engines were both developed together, in case what became the actual GT3 3.6 (GT1 derived block) failed racing regulations and/or reliability requirements for a successful homologation.
In other markets, such as Germany and Japan, these options (along with M030 sports chassis, bigger wheels and sports seats etc) were sold as one.
In the guise of a 2WD (but C4 chassis) 3.4 X51 with Cup Aerokit it was an additional model in its own right called the "Carrera Cup" in Germany and the oddly named "PowerUp" edition for Japan.
When they were released in the UK, the Cup AeroKit and PowerKit were separated as options (XAA and X51 respectively).
The X51 was almost certainly only given an additional 20 BHP for "political" reasons - the much more expensive GT3 996.1 3.6 M96/76 only developed 360 BHP.
In 2000 the X51PowerKit cost £8,725 from the factory.
Expensive as it was (and with on-paper low absolute power enhancement), at least the 996 PowerKit had extra lubrication efficacy (via a larger alloy racing sump baffle with valved apertures, dual chamber oil pump and additional lubrication plumbing on cylinders 4-6), additional third cooling radiator, high lift valves, revised camshaft and optimised (machined and polished) exhaust ducts.
The X51 was not available in the US in 996.1 guise.
Attached images:
Sand-cast aluminium cross-section modified intake system
Optimized exhaust ducts (machined and polished)
For two years this was the most powerful 4 seat or 4WD model (the Turbo had yet to be released).
Significantly, it is not just power output upgrades, having both additional cooling (centre radiator) and lubrication upgrades (high-G sump baffles, additional pump and oil lines).
Those two options are almost worth the entry ticket alone: as the 996 cylinder failures almost always involve the overheating and under lubrication of cylinder number 6, these modifications go someway to mitigating the seizures.
The 996 X51 was the sister model to the GT3 during development.
Porsche Motorsport Division parallel developed the narrow body C2 with C4 strengthened front chassis/body structure, track suspension and roll cage and even the aerodynamic Cup AeroKit (note: its note even officially called the GT3 kit), but with different engines.
The GT3 3.6 (M96/76) and X51 PowerKit 3.4 M96/01S engines were both developed together, in case what became the actual GT3 3.6 (GT1 derived block) failed racing regulations and/or reliability requirements for a successful homologation.
In other markets, such as Germany and Japan, these options (along with M030 sports chassis, bigger wheels and sports seats etc) were sold as one.
In the guise of a 2WD (but C4 chassis) 3.4 X51 with Cup Aerokit it was an additional model in its own right called the "Carrera Cup" in Germany and the oddly named "PowerUp" edition for Japan.
When they were released in the UK, the Cup AeroKit and PowerKit were separated as options (XAA and X51 respectively).
The X51 was almost certainly only given an additional 20 BHP for "political" reasons - the much more expensive GT3 996.1 3.6 M96/76 only developed 360 BHP.
In 2000 the X51PowerKit cost £8,725 from the factory.
Expensive as it was (and with on-paper low absolute power enhancement), at least the 996 PowerKit had extra lubrication efficacy (via a larger alloy racing sump baffle with valved apertures, dual chamber oil pump and additional lubrication plumbing on cylinders 4-6), additional third cooling radiator, high lift valves, revised camshaft and optimised (machined and polished) exhaust ducts.
The X51 was not available in the US in 996.1 guise.
IN THE EXPLODED DIAGRAM:
7 Modified oil pan partition box (larger alloy baffles with aperture valving replaces small plastic baffles)
8 Uprated exhaust gasket for larger exhaust ducts
9 Adapted exhaust manifolds with larger cross-section and optimized flow behaviour
10 Alternative suction line on AC compressor (modified for space reasons)
11 Optimized inlet and exhaust ducts (machined and polished)
12 Modified intake system (modified cross-section - sand cast aluminium replacing plastic)
NOT SHOWN:
Revised cylinder heads
New 996 mark 1.1 revised swirl piston set (3.4 only)
Modified valves (including profile and longer shaft)
Larger lift camshaft
Additional dual chamber oil extraction pump
Additional oil extraction pipe (to service cylinders 4-6)
Additional third radiator (excl. C4S)
Alternate Tri-metallic catalytic converter
New shields for new oil suction pipe
New underside panel in transmission area
Modified fuel maps for DME (rev limit raised by 200 rpm)
Attached images:
Sand-cast aluminium cross-section modified intake system
Optimized exhaust ducts (machined and polished)