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I have been making a few engines on the Sandbox mode recently that will be included in my car company through the years. So to keep profit high, obviously it'll be best to keep costs down and keep quality. Therefore I have a few questions:

1) When adjusting the stroke and bore, I noticed for a while now that when the stroke hits a certain point (when increasing it), the lifespan suddenly decreases. How and why does this happen?

2) When you mass produce products, the more parts you make the less each individual part costs. Is this true in the final game?

3) If question two is answered yes, then I'm most likely to produce as many of these individual parts as I can on every car that comes out of the factory. Would the bore and stroke sizes, fuel system and head and valve set-up be the same if I were to produce an inline 4 and a V8 engine?

P.S Thank you again for your great work so far on the game!!

1 is an easy one from a pure engineering POV -
bigger piston = bigger surface area = more friction = reduced life span.

A large stroke has a significant negative effect on the lifespan of an engine if the rev limiter is set too high. Stroke is distance the piston travels upwards and downwards during a stroke. Increasing the distance the piston has to travel (the stroke) in 1 RPM increases the piston speed creating more friction and putting more stress on all of the internal components of the engine, thus reducing lifespan. Try reducing the rev limiter when you have a high stroke. Hope that answers your question!

Mean piston speed is a reasonable indication of how stressed an engine is and it's very easy to calculate, but peak piston acceleration is what breaks stuff.



The "lifespan" of the engine is the mean time before something, anything, breaks. So its really a measure of the reliability of the least reliable part in the engine. For instance if you use mechanical fuel injection as early as it's available it's really going to limit the lifespan of the engine even if everything else is as reliable as a hammer, because early mechanical injection has a low lifespan it becomes the weakest link in the chain, the bottleneck. What you're seeing when increasing stroke or rpm suddenly starts killing the lifespan is the point where the lifespan of the rotating assembly becomes the limiting factor. Before that point the lifespan on the rotating assembly was still being reduced by the increasing stroke/rpm, but something else was even worse so it wasn't affecting the lifespan of the engine as a whole.

2. In a word, yes. However, there's a limit to economies of scale (what you're describing).
3. If a firm becomes too big, it becomes increasingly inefficient.

That's what's going to make the business and finance aspect of the game so much fun! You have to find the right balance.

1) - That is indeed going to be caused by piston speed starting to stress some bottom end components to the point of unreliability.

2) - There will be a lot of costs in establishing a new factory, tooling it to produce an engine/car, designing that engine & car etc. So the more of the product you make, the more the costs will be spread across lots of items and the cheaper it'd be per unit. Also large scale production facilities will produce more stuff per dollar as small factories.

Thank you all for your quick and detailed replies!!! I now have a better understanding on both the stroke and bore side of things and the business side of the game. Cheers!!!