So I decided to write a post to show my work on piston engines in SP till now since I think it has reached a performance level not only just as a gimmick but as an actual engine. And I don't think I will have more work and improvement upon it because I've been pretty busy lately and I think I kinda reach some kind of limit for piston engine in SP. Thus I wish to share my development and let others improve upon my works.

a disclaimer: I'm not a STEM field guy, in fact, I'm a musician. So my use of word may not be correct or exact enough, just bare with me for one sec

so first you had to have the mod #LimitlessSpin#
Or until SP disable the spin limit

for this half, you only need the building skill to build it

and a basic replication

To replicate piston action in SP you only need a few stuff
Piston (to give reciprocating work)
Piston pin (connect the piston to the connecting rod)
Connecting rod (Con-rod for short)
Con-rod bearing(Here I use a Rotator instead of a hinge because the precision from con rod bearing to crankshaft bearing is very crucial)
Crankshaft
Crankshaft bearing

so first how a basic reciprocating engine works in SP

without any FT works, the piston con only start from 2 positions: Top and bottom (Default and extended)
And the corresponding crankshaft position (the bumping bit) is 90 and 180 degrees (directly up and downwards)
As you switch the cycle option on the piston, the con-rod will translate the up and down motion(sin wave) to rotating motion on the crankshaft as output

And theirs 3 key ways to make a smooth running engine in SP
1. is to make sure you have the travel of the piston (how much it extend) match to the diameter of the circle which the base of the con-rod is traveling (basically it is the distance between the center of con-rod bearing and crankshaft bearing *2)
2. is to not have too much slack between the the parts
3. is to balance the reciprocating force of the piston (it can probably be done by putting some weight in the crankshaft as a counterweight, but it is just easier to make a set of pistons to counterbalance the forces, such boxer, Inline 4/6 V8/12 Two row of radial engine, etc.)

but you may ask, as the piston in-game has near-infinite pushing power and traveling speed (for the context of an engine), does that mean you can have infinite output?
The piston may be all-powerful, but everything that is soft-connected is a way to have the piston not putting down the power, and thus limiting the torque and the power output it can have.

Size matters
as you scale up a piston engine just by size, you also scale up the size of the crankshaft. It increases the leverage and thus decreases the need for rigidity on the con-rod bearing part. The ability more force at the same RPM means the ability to have higher output.

And now you have some basic knowledge of how to have reciprocating piston outputting rotational force and with the knowledge you can basically build This and the engine part of This

The advance post is on the way