Flat Engine Revision and Balance Shafts

1: I think the Engine Designer needs a revision on a flat engine bore and stroke design, as flat engines are horizontally opposed, so it usually have an oversquare design (bore larger than stroke) because increases in stroke length will increase in overall engine length, so here are two flat engine recreations as an example of typical flat engine design.

My recreation of a Flat-4 engine (1.7 L, 87 mm bore and 72 mm stroke).

My recreation of a Flat-6 engine (3.3 L, 96.9 mm bore and 75 mm stroke).

2: I have found out that the balance shafts are used in some inline-3, inline-4 and V6 engines to reduce vibrations, such as Daihatsu C-Series (inline-3), Alfa Romeo Twin Spark/Porsche M44 (inline-4), and Mercedes-Benz M112/M272 (90-degree V6).

References: Boxers and Bore vs Stroke :: Automation - The Car Company Tycoon Game General Automation Players Forum
Why The Boxer Engine? | Subaru Australia
Balance shafts (Note that the balance shaft has been suggested 8 years ago, but never been discussed in that topic).

And what should be revised in terms of “bore and stroke design”? That sounds quite vague. I can’t see a problem there.

As for balance shafts, yes but no. I went more or less that route and got nowhere. Dump quality into the bottom end.

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Oh, the flat engine bore and stroke design should be revised in that the increase of engine bore length will not increase the engine dimensions (unlike inline and V engines), however, if the flat engine’s stroke length increased, the engine dimensions will be increased as cylinders are opposed.

This is the reason why the flat engine looked much larger than I expected, despite the flat engines traditionally have short stroke design.

That would be a plain, unrealistic exploit. No way a 70 mm bore and a 95 mm bore boxers will be the same size. Both bore and stroke change the external size of the engine for all types of engines, but they do it in two different ways. Maybe, just maybe, the bore should affect the height of the bank (so the width of the engine for boxers) less, and the stroke should affect it more.

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Except that stroke on a boxer/flat wont increase length, it will increase width; more bore will increase the length. The model just scales with the sliders, it doesn’t actually adjust the connecting rod length.


more bore = fatter cylinders = bigger valvetrain (valves; camshafts; rocker covers and the likes) = more width (relative to car direction if longitudinal)

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Don’t know if you’re replying to me @Elizipeazie, but, I mean that, in a horizontal layout:
If the X axis is across, Y is up and Z is away, relative to a viewing position in front of the vehicle, then X= width, Y=height and Z= length/depth.
More bore will increase Y and Z.
More stroke will increase X.

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this still apllies, with X being referenced (left to right when viewed up front)
just like a 4-pot getting taller (Y-axis) with added bore, the flat-4 will get wider

though i do agree that stroke should have a much greater effect on x than bore does