That I3 looks like it was designed in the US in early 50's,
modern engines almost always have very small walls between cylinders.
AUDI have on nearly all their engines 5.5mm between the bores.
(90mm C-C with 84.5mm bore, or 88mm C-C with 82.5mm bore)
Chevy LS 4.4" C-C 3.9" up to 4.125" bore. (.5" 12.7mm down to .275 6.985mm)
So maybe the game needs assets that reflect the progression in engine design over the decades.
Nope, ignore this "rant" and make the game instead, prehaps for the mythical Automation 1.0+ the extra assets can be made.