# Bore/Stroke alternative

Didn’t find any suggestion like this, so here goes.

With the current engine designer, we use sliders for bore and stroke, and have the derived values of engine displacement and over/undersquareness. This is excellent when trying to replicate an existing engine - just put in the bore and stroke sizes and voila, there’s the correct displacement and “squareness” (For lack of a better term) or piston ratio.

Often, I find I want to design an engine of an exact size, or compare different classes of engine with the same piston ratio. Would it be useful for others to have alternate sliders for displacement and over/undersquare, which would make bore and stroke the derived values?

I don’t quite see why you would want to add this layer of abstraction when the core values can be tweaked directly with the same amount of input parameters?
Bore and stroke are primary technical stats you find for every engine, “1.2L, 10% oversquare” is something I’ve never seen as designation.

It’s more for a level of convenience. Suppose I want to make an exactly 1999cc engine. With the current system, I would have to solve pir^2d * c (where r=bore/2, d=stroke, c = # of cylinders) for every possible piston ratio I want to compare the performance of. The math isn’t hugely complicated, but can be onerous and could save a lot of blind sliding for an end user who doesn’t want to run the numbers.

This scenario actually happened to me. I was doing comparisons of equal capacity v6’s and l4’s.

Wow… I’m impressed with your level of commitment but even ending up with 1997cc it will only be maybe 9 clicks up or down at a rate of roughly 1 bore click to 2 stroke clicks on a 4cylinder to find your magic number. Also if you are looking to design a higher revving engine the ability to decrease the stroke alone allows you far greater control over tthe rotational velocity of the pistons then just saying a percent of over square. I think you are just overthinking the issue.

If you’re suggesting I might be obsessing over minutia, you’d be ABSOLUTELY correct! I’m probably off on a tangent to what I’m trying to suggest. Let me revise my suggestion to this: I would find it very useful in the engine designer if there were a way to lock engine displacement and piston ratio (but not both simultaneously, of course. That would not be so useful.)

Hmm… Actually have a button to lock the ratio might be a interesting idea, the game already knows how to do it, but I would think it would only work in the engine variate tab, The family system will encourage sticking to time tested designs rather than redesigning for each engine size.