Diagrams

This diagram illustrates where to attach the engine stand adapter. Depending on where you get it, it should bolt onto three or four studs on the left vertical edge of the front iron. Done right, the engine should be fairly balanced, and should stay in whatever orientation you spin it. Done wrong, it'll chop your hand off at the wrist the next time you pull out the locking pin!

Coolant is drawn from the bottom of the radiator by the water pump, and forced through a series of channels in the left side of the core. It is also forced out through a small fitting into the turbos. At the rear of the block, it crosses through the rear iron to the other side of the block, then returns back to the front to the water pump. Also at the rear of the block is a fitting on the left vertical edge of the rear iron that feeds the cabin heater core. The heater returns to the water pump via a separate hose.

The water pump contains a thermostat that bypasses the radiator while cold. As the engine warms up, the thermostat opens, closing the bypass, and forcing coolant to flow out to the radiator. The system also contains an air separator tank.

Oil begins its life in the oil pan, and is drawn up through a siphon tube into the oil pump. From there it is pumped out through a fitting in the left side of the front cover, through a hose and into the oil cooler. The oil from the cooler returns via another hose to a plate on the top left of the rear iron, passes through an oil filter, then enters two holes in the top of that plate.

One hole is plumbed directly to an oil pressure regulator, which bypasses excess oil directly back into the oil pan. The other hole is plumbed through the block to the stationary bearings, and into the eccentric shaft to squirt oil onto the bearings from that side as well. Inside the front cover, oil may pass into the oil metering pump, which measures small quantities of oil (based on rpm) directly into the rotor housings to lubricate the apex seals. Finally, a fitting in the top left side of the front iron feeds oil through a hose to the turbos, which return the oil through two fittings at the bottom right sides of the rear iron and front cover.

The following modifications are commonly made for aircraft use:

1. Remove the thermostat, and block off the bypass hole. (Thermostats are a common failure item.) However, note that running the engine “cold” for excessive periods of time is can build up carbon and sludge deposits, and reduce its lifespan.¹⁾
2. Remove the OMP and block off its port with a small aluminum plate.
3. Remove the air pump. Note that you will either need a different belt or an idler pulley. The idler pulley is recommended to avoid side bear on the bearings.

The tension bolts should always be removed and installed in the block in a certain order, specified in the diagram above.

The above diagrams illustrate how the major accessories are attached to the engine.

The above diagrams illustrate how the front cover assembly is constructed, and how the rotors and housings go together.

All bolts are metric, and may be identified by measuring (with a caliper) the outside diameter of the bolt across the threads, and the distance from the tip of one thread to the tip of the next. Because metric thread pitches are so close together in size (have you ever tried to tell the difference between 1.0mm and 1.25mm?) it may be helpful to measure ten threads, then divide by ten to get the final value.