How to Build a Ford 302 Engine for a Turbochargerby Richard Rowe
Introduced in 1968, the 302 was a hay-maker punch in the muscle car gut. With high compression, massively high flowing cylinder heads (in Boss form), high production number and low cost, the rev-happy 302 quickly became a popular alternative to the expensive big blocks that regularly graced magazine covers. Re-dubbed "5.0" in the 1980s, this engine remains popular with hot-rodders for its strength, versatility and outright power potential. These engines take particularly well to turbocharging, too; turbo 5.0 Mustangs tend to dominate ad nauseum in the several NHRA and IHRA racing classes where they're allowed to play.
Start with a stock 1986 or older, "roller cam" engine block with at least 50,000 miles on it (referred to as a "seasoned" block). The iron crystals in the engine block casting are actually fairly weak from the factory; the block needs a few thousand heat cycles before the atomic structure really cements, and the block reaches its optimum strength. If you're building an engine with over 450 horsepower, start with a stronger aftermarket iron block from World Products, Dart or Ford SVO.
Purchase and install a forged 4340 steel crankshaft, available from a variety of manufacturers starting at about $400. When polished and nitrided (nitrogen impregnated) for strength, a stock crankshaft is good for about 450 horsepower.
Install a set of forged steel, H-beam style connecting rods if you're going for anything over 550 horsepower. A set of cheaper forgings is good for a conservative 450 horsepower, and the strongest set of stock connecting rods is good to about 400 as long as you keep RPMs under 6,500.
Use a set of forged aluminum, 8.5:1 dished pistons and specialty turbocharger piston rings. Install a stud girdle on the bottom of the crankshaft main caps if using a seasoned stock block.
Install a set of stock Ford GT40 or GT 40P heads from a 1990's 5.0L Mustang or post-1995 Explorer. Although they flow well from the factory, you should consider having these heads ported and polished to extract maximum airflow. If you're looking for more than 550 horsepower, consider an aftermarket set of heads from Airflow Research, Edelbrock or Ford Racing.
Add a Ford Racing E303 cam for a good idle and good top end power, an F303 cam for 600 horsepower-plus applications or an equivalent camshaft and matching valve train from another manufacturer. Install a ported aftermarket Cobra upper and lower intake manifold.
- The Ford 302 has a secret weapon where twin-turbocharging is concerned. The exhaust manifold flange is completely symmetrical, so you can actually use a set of flipped-over, stock Mustang "shorty" headers as turbo manifolds. This can save you some big bucks on the final tally.
Items you will need
- Full set of basic hand tools
- Full set of metric and standard sockets
- Tools for cutting, grinding and welding metal
- Fabrication and metal-forming equipment
- Torque wrench
- Clearance and measuring tools
- Thinkstock/Comstock/Getty Images