This is actually common for a 2 stroke type engine and used in things like gas golf carts and snow machines. The direction the engine is started is the direction it runs.

So to accomplish this for propulsion, you'd add a reverse polarity switch for your starter and you're good to go.

You can even get a (2-stroke) Detroit Diesel to run in reverse.

You don’t want to do it very long, because they don’t make oil pressure in reverse.

> You don’t want to do it very long, because they don’t make oil pressure in reverse.

US energy policy has entered the chat.

Yeah, in theory, there's not a lot about an engines running direction that matters, its all the stuff that's hooked up to it.

As you start getting into more complex engines, where you have fuel injection, timed spark plugs, oil pumps, transmissions it becomes untenable, but not because a v6 can't run backwards but because you'd have to rebuild and time all the support systems.

A low speed marine diesel like you'll find in a large container ship is not your granddaddy's 6V71. They are complicated, yet simple. They are indeed direct drive (possibly through a reduction gear) and they do indeed operate both in forward and in reverse. See e.g. [1].

[1] https://chiefengineerlog.com/2022/06/24/main-engine-fixed-pi...

Yes, defiantly not saying that's not how these work, and I do know that large boats tend to be direct drive. I'm just pointing out that most engines could do this and the limitation is generally how it interfaces with the external components and not as much a function of internal combustion type engines.

For example, a transmission would expect the engine to always run in the same direction, but given correct fuel and ignition timings, it doesn't really matter which way the crankshaft is turning while things are running.

I accidentally installed an injector pump 180° out of time on a MB OM617 and it "ran" kinda.. with a massive white smoke screen. I was shocked it even started.