Algodoo

Your butt-blistering 110 rad/s is 1050 RPM. just multiply rad/s by 9.54

Tbh it's pretty good as a start, but there are some things you're doing backwards.
Use a circular, balanced flywheel, otherwise it'll be all over the place
Use a spring instead of a polygon for the rod (constant 1e10, damping +inf, and also set "forceDirectSolve" to true, on the script menu), they are miles ahead
Use less reciprocation (rod closer to the center of the flywheel) and maybe a shorter rod, honestly it's more of an aesthetic thing
Don't use polygons for ANYTHING that collides with a lot of force (for example, the cylinder walls). Use boxes there. Any actual physics entity (circles & boxes) are way better at physics than polygons and also lag a lot less. even if the polygon is just box-shaped, it'll be worse
To get any real power from the engine without making it explode, you have to set the spring with the negative damping to legacyMode 0 on its script menu. you should be able to go stupidly high on constant
And probably the most important of all, use VERY HIGH DENSITY on all the colliding parts! For example 100 or more on the piston. High density is like higher frequency but without the horrible performance drop.

Btw if your engine explodes as soon as the scene starts or stutters and freezes it's most probably because a spring is connected to a low mass object on one of its ends. just get the density to something reasonable like 100, 200, mabe even 500

Follow all this stuff and you'll be able to make a realistic size engine

also where's a scripted hinge??
If you mean the one with bend on, that's not set correctly. you need to set bend to true, bendConstant to whatever amount of Nm you want (just +inf) and bendTarget to the angle in between (just use 0).
If the connection is still horribly weak then you need to incerase the density on the objects that the axle is connected to. a lot too

And lastly use a much, MUCH lower hingeConstant on it, usually 1e-30 is the lowest value you can use. that value is the Newtons that the hinge does when stretched, so 1e-30 is 0.000000000000000000000000000001 N while you're using 900 N. that's around 90 Kg of force

@The Linkage With butt blistering, it was purely meant with irony in mind. But thanks for the info.

And btw, hows the code line called to make a spring stronger or something? to actually have a throttle?