Caleb James DeLisle on Nostr: Firstly, horizontally opposed engines are tricky, because the block is in halves. In ...
Firstly, horizontally opposed engines are tricky, because the block is in halves.
In a normal engine, the block is one piece and you use main caps to hold the crankshaft in. In a horizontally opposed engine, you typically use long studs to hold the engine halves together. This is really dodgy stuff because if the bolt flexes, the halves shift, and any shift at all tweaks your main journals which practically guarantees you spin a main bearing.
Aircraft engines LOOK like you can just easily swap a cylinder, but nooooo, those little nuts holding down the cylinder are actually holding the engine together. You'd rather move heaven and earth than take the load off of those studs.
Now mercifully, Subaru thought better than to share the main stud with the head bolt, but still their engines have had a lot of problems, particularly with oil not reaching places where it should, and with head gaskets failing.
In a normal engine, the block is one piece and you use main caps to hold the crankshaft in. In a horizontally opposed engine, you typically use long studs to hold the engine halves together. This is really dodgy stuff because if the bolt flexes, the halves shift, and any shift at all tweaks your main journals which practically guarantees you spin a main bearing.
Aircraft engines LOOK like you can just easily swap a cylinder, but nooooo, those little nuts holding down the cylinder are actually holding the engine together. You'd rather move heaven and earth than take the load off of those studs.
Now mercifully, Subaru thought better than to share the main stud with the head bolt, but still their engines have had a lot of problems, particularly with oil not reaching places where it should, and with head gaskets failing.