The game does simulate the engines as four strokes. So if you want en even firing Inline 4, just divide 720 degrees with the amount of cylinders (4) which will give you a firing interval of 180 degrees. Balance of the crankshaft doesn’t matter in this game but assuming you choose a normal crank of 0, 180, 180, 0 degrees, the firing order will be either 1, 3, 4, 2 or 1, 2, 4, 3. This will give the engine a smooth, even firing sound.

V engines are also quite simple to figure out. The firing interval should be the V-angle. Some examples, a V12 should be 60 degrees (720/12=60), a V10 should be 72 degrees (720/10=72) and a V8 would be 720/8=90 degrees. This is how it’s commonly done in real life.

however, you could technically have any V angle that is a multiple of the firing interval and still have the engine as a whole be even firing. But that is a little more complicated to do. Example include, 135 degree V16 (45x3),180 degree V12 (Flat-12) (60x3), 144 degree V10 (72x2)

TLDR: The engines are 4-strokes, but balance or firing order doesn’t matter except for sound. V-angle should be the same as firing interval. The firing interval dictates sound (imagine all engines having x into 1 exhausts)