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Cosworth 79mm 2.5L Crankshaft (04+ STi, 06+ WRX)

Item # 20002315

Increased engine performance often means increased engine speed and load. Original factory crankshafts may not be able to withstand the added stress resulting in catastrophic engine failure. Additionally, factory Subaru crankshaft rod journals are lubricated from only one main oil feed. Cosworth billet crankshafts feature full-flow oiling whereby each rod journal is lubricated from two main sources. This provides superior lubrication during sustained high rpm use preventing rod bearing failure. Cosworth Subaru crankshafts are manufactured entirely in house from EN40B steel in a light weight-high strength design with a unique Isotropic Superfinish.


  • Stroke-79mm (EJ25)
  • Full-flow oiling
  • Billet Steel EN40B
  • Approx. weight 18.01 lbs. (OE cranks weighs 20.4 lbs.)


Isotropic Superfinish: The ISF Process is a chemically accelerated vibratory mass finishing process Any time two metal parts come into contact with each other, the resulting friction causes heat build up. These high temperatures cause wear and over time reduce efficiency and eventually create the need for replacement. By creating a smooth and shiny finish, the ISF Process improves the life and efficiency of moving metal parts. Increased life translates into lower operating costs as well as better performance. In extreme environments, such as automobile or motorcycle racing, every component must work in harmony at 100% capacity. Races are won and lost by fractions of a second, so it all comes down to getting the most power output possible. With the ISF Process, the energy normally lost to friction is now available in the form of increased power output. Once friction is reduced, the engine will run cooler allowing for longer durability of parts and fewer failures.

  • Allows a freer movement of parts with less surface resistance
  • Extends life of parts and reduces risk of part failure during operation
  • Reduces maintenance expenses and fuel costs
  • Improves oil shedding
  • Increases power output resulting in increased speed