How To LS Swap Your Porsche 996 / 997

1. Chassis Preparation & Metal Modification

• Trimming: Cut the rear tray/terminal sheet metal and cross structure from passenger to driver side for thermostat plumbing, water pump, and accessory clearance.
• Structural Integrity: Removing this section does not take rigidity out of the chassis because it is a spot-welded terminal piece.
• Finishing: Box the cut structure for a cleaner fabrication look, then dust with factory-color paint to prevent rust and keep a professional finish.

2. Cooling System & Brake Booster Plumbing

• Heater Core Lines: Route inner and outer heater core hoses between the chassis and e-brake cabling, zip-tying to nearby coolant pipes.
• Firewall Routing: Run lines across the firewall behind the steam vent line. Secure the innermost hose with an insulated P-clamp.
• Expansion Tank Connections: Tee the innermost line into the bottom of the expansion tank with a 3/4" x 3/4" x 3/4" barb fitting; use a 3/4" x 5/8" barb fitting on the top line.
• Brake Booster: Cut the factory booster hose and repurpose with 5/8" hose bent outward. Use a 5/8" to 1/2" barb zip-tied to coolant pipe to connect the 1/2" hose from the back of the intake manifold.

3. Engine & Transmission Installation

• Equipment: Use a 1,000 lb table cart (such as Harbor Freight model) to marry engine and transmission before lift-in.
• Components: Confirm adapter plate, flywheel, clutch kit, and engine harness are installed before dropping powertrain into the car.
• Critical Clearances: While lowering chassis onto the engine, monitor ignition coils and plug wires to avoid pinching or cracking.
• Torque Specs: Motor plate bolts must be torqued to 38 ft-lbs.

4. Electrical & Wiring Layout

The CPE harness is designed in a "U" shape, with the base tucked under the brake booster line at the back of the engine.

• Bank 1 (Passenger Side): Route O2, crank sensor, and starter wire between block and exhaust manifold. ECU and Porsche chassis connections wrap around bank 1 ignition coil bracket.
• Bank 2 (Driver Side): Includes AC pressure switch, compressor signal, and oil temp sensor.
• Wiring Safety: Place AC and oil sensor wiring in the channel between AC compressor bracket and block. Pinched wires can pop the AC compressor fuse.
• Battery Cabling: Run cable from starter, zip-tie at base of harness "U", and follow factory conduit to passenger-side junction box.

5. Powertrain Mounting & Brackets

• Foremost Position: To retain factory trunk latch, move entire powertrain one inch forward (CPE foremost position).
• Transmission Horseshoe Bracket: Cut ears, remove a few millimeters, and re-weld for fitment. Turbo GT mounting holes are used for this setup.
• Subframe: Use a billet lower subframe brace, significantly stronger than the factory cast aluminum brace.

6. Fuel System Upgrades

For E85 or Flex Fuel, an upgraded fuel system is required.

• Fuel Pump: Install a Walbro 450 inline pump and use the OEM in-tank pump as a lift pump.
• Flex Fuel Sensor: Integrate into harness and run off fuel rail or mount remotely under the car with extension.