How Do I Use a Northstar V8 in Rear-Wheel Drive?by Richard Rowe
GM's Northstar engine was something of a radical when it was introduced in 1991. This little 4.6L V8 had dual overhead camshafts and an high-strength aluminum block purpose built for reliability and sustained rpms. The Northstar's only real competition on American soil was Ford's modular V8, which also debuted in 1991 and matched the Northstar spec for spec (even down to its 4.6L displacement). Northstar was specifically designed for front-wheel-drive applications only; easy RWD conversions didn't come for more than a decade after its introduction.
Acquire a wrecked 2004 to 2009 Cadillac SRX, XLR or STS if you want a naturally aspirated powerplant, and a 2006 to 2009 Cadillac STS-V or XLR-V if you want the supercharged version. Although you can adapt earlier versions of the Northstar for rear drive use, almost nothing about their blocks, oil pans or intake manifold will line up with a rear-drive car's chassis, transmission or firewall. These later engines are designated LH2 (naturally aspirated, 320 horsepower) and LC3 (443 to 469 horsepower) and have the correct motor mount holes and transmissions provisions cast into the block.
Disconnect the donor engine's electrical, water, fuel and oil lines, making sure not to damage anything. The wiring harness is one of the most crucial elements of this swap; start snipping wires like you would when jerking the engine out of a 1976 Vega and you're asking for trouble. Do yourself a favor and don't even touch this engine without buying a Chilton or Haynes manual; it's $20 well spent.
Remove the donor car's engine and transmission as a unit. You'll need to remove the hood, radiator and A/C condenser, but these engines are designed to come out through the top. The manual you purchased will contain detailed and illustrated instructions on engine removal. Follow them to the letter, and keep a checklist of duties performed.
Remove the engine control and transmission control computer from the donor car, along with the complete wiring harness for each. Remove the transmission crossmember and shifter/sensor assembly from the donor. Unbolt the motor mounts from your donor car frame and put them back onto the engine.
Drop the engine into your recipient's engine bay so that the motor mounts land on its crossmember. Go under the car and figure out how you will modify your existing or donor crossmember to support the transmission.
Support the back of the transmission, and weld the motor mounts in place on your main crossmember. Slip your modified transmission crossmember under the rear of the transmission and install it. At this point, the engine is physically installed in the car.
Replace your stock fuel pump (along with the fuel tank if it will fit), fuel filter, battery, radiator, A/C condenser, transmission cooler, shifter assembly and ignition key mechanism with those from the donor car.
Hook the engine and transmission up to their respective computers with the stock wiring harnesses. This may require lengthening or shortening certain harness sections, but do your best to mimic the donor vehicle's placement and wiring configurations.
Connect all of the engine's ancillary systems, including the charging system, power steering, brake booster, exhaust pipes (including catalytic converters and oxygen sensors), air intake, cooling system and oil lines.
Take the recipient to a driveshaft shop and have them fabricate a new driveshaft at the proper length with the recipient's differential flange and the donor's transmission yoke.
Items you will need
- Basic hand tools, full set
- Metric and standard sockets, full set
- Tools for cutting, grinding and welding metal
- Fabrication and metal-forming equipment
- Torque wrench
- Clearance and measuring tools
- Chilton or Haynes manual for donor car and recipient
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