Oil

System design

Banking in Engines

Oil System Differences

In a stock motorcycle engine, the oil is stored in the oil pan as an internal oil pan. This is called a “wet sump” oil system. On a motorcycle, this works during hard lateral turns because the motorcycle itself leans into the turn, allowing the oil pickup to remain submerged during the turn. In a four wheeled vehicle, the engine cannot tilt into the turn, and the oil is forced against the side of the pan.

Dry Sump

Dry Sump Schematic

In a dry sump oil system, the oil for the engine is stored in an external reservoir. The oil that collects at the bottom of the engine is quickly removed by a scavenging pump, and routed into the external reservoir from which the supplies for the engine and the turbocharger are drawn. A common industry solution, a dry sump is often used in very high performance engines for a variety of reasons, including reducing the load on the engine by pumping the oil electrically, or reducing the frictional work the engine has to overcome by reducing windage. A key advantage of a dry sump for FSAE is that the pan thickness can be much smaller due to the external reservoir replacing the wet sump. This in one dramatic swoop eliminates both the oil starvation problem during cornering and allows for reduced center of gravity by bringing the engine which is exceptionally heavy closer to the ground. A dry sump is common in FSAE for forced induction applications as high lateral accelerations reached in the FSAE competition greatly increase the chances of temporary oil starvation of the turbocharger[1].

Oiling for Turbochargers

The engine has a robust internal oil management and supply system, so a brief or inconsistent oil supply will have limited consequences for the engine itself. However, the turbocharger is spinning at well over 200,000 rpm, meaning even a small perturbation in oil supply will spell disaster for the bearing system. [citation needed, our source this in our senior proj was alumni communications]