The Cosworth Dry Sump Oil System not only eliminates oil starvation, but also produces a vacuum in the crankcase so that excessive crankcase pressure no longer becomes an issue. Also, there are small horsepower gains from vacuum being present in the crankcase since the laws of aerodynamics do not apply in a vacuum.
Complete crankcase oil scavenging reduces excessive and residual oil that can cause blow-by and power loss. A Dry Sump also offers more consistent oil pressure to the engine, improved scavenging, and increased ring seal due to greater pan vacuum.
The Cosworth Dry Sump System for the Subaru EJ20/EJ25 replaces the original oil sump with a machined from solid, low profile alloy pan with twin scavenge ports, internal baffling and o-ring sealing. A two stage scavenge pump driven by a HTD belt, mounted to a heavy duty bracket evacuates the oil from the engine.