Visual Entertainment and Technologies Forum

The current system for bore and stroke and calculating engine sizes is weird and produces a number of odd results. Like V12's being wider than they are long or a 3L I8 being the same length and width as a 3L I3 (or very close too it).
Add to this, bore, stroke, length and width all being effected by three sliders each (directly or indirectly) makes for an unintuitive interface that can be hard to grasp.
I believe the following system will fix this without making any of the sliders currently in use irrelevant.

Bore and Stroke:
Remove the effect length and width have on these values. The bore slider has access to the full bore range and the stroke slider has access to the full stroke range (from 40mm all the way up to 260mm or whatever it happens to be that year). No, this wont make length and width sliders irrelevant, keep reading.

Engine dimension:
The bore and stoke are now used to calculate the minimum engine size, along with a few other factors. Now, the lengths and width sliders determine how much effort you've put into making the engine as small as you can for the displacement you've chosen.
These equations will also eliminate the previously mentioned anomalies as well.
Length:
Engine lengths equation becomes the following (with a few tweeks):
((Bore x Number of cyliners x Engine layout length modifier x Fuel type modifier) + Valve train factor + Induction factor) x Length slider multiplier

So, the Engine layout length modifier for an inline engine might be 1.2 while a V or Flat engine might be 0.6 and a W (3 banks) might be 0.4 and a VV (4 banks) would be 0.3. Or something along those lines.
Most Fuel type modifiers would be 1 but diesels tend to be a bit bigger (they have thicker walls to withstand the vibrations, etc) so theirs would be 1.1 or 1.05 while Hybrids have lots of extra stuff bolted onto them so theirs might be 1.2.
Valve train factor would be 50mm for a 2 stroke, 100mm for an F,L or T head and 150mm for a SOHC or DOHC. Or something along these lines to cover the belts and gears that need to be bolted to the front of OHC engines but aren't needed so much for block mounted cams or 2 strokes.
Induction Factor is to take into account the size of the turbos, the extra piping and pulleys and fan belts and stuff.
I reckon you could get away with using the same Fuel type modifier, Valve train factor and Induction Factor for both length and width, it's not super accurate but it seems reasonable.

Having the length slider all the way to the left would make the engine as short as possible (so, multiplying the above equation by 1) while sliding it all the way to the right means you've not invested any time in reducing the size of your engine at all so it would multiply the length by 1.25 (or, maybe a bigger number if you think that's necessary)

Width:
Engine width equation becomes the following (again, with some tweeks):
(((The largest value of bore or stroke) x Engine layout width modifier x Fuel type modifier) + Valve train factor + Induction factor) x Width slider multiplier

Engine layout width modifier for an inline engine might be 1.5, for a V it might be 2.5 and for a flat it might be 3.5 a W would be the same as a flat while a VV (4 banks) might be 2.6 or 2.8.
As suggested before, you could probably get away with using the same Fuel type modifier, Valve train factor and Induction factor for both length and width.

Having the width slider all the way to the right would make the engine as narrow as possible (so, multiplying the above equation by 1) while sliding it all the way to the right means you've not invested any time in reducing the size of your engine at all so it would multiply the width by 1.25 (or, maybe a bigger number if you think that's necessary)

Weight:
Weight would be calculated by an equation something like the following:
(Length x Width x Engine layout weight modifier x Fuel type modifier x Induction modifier x K) x Weight slider multiplier
K would be a slowly decreasing value over time to represent the introduction of lighter, more advanced materials. I don't know what the value of K would be but it shouldn't be too hard to work out.
Engine layout weight modifier's purpose would be to balance the different engine layouts. For example, a V6 might be more compact than a I6 of a similar volume but it's not necessarily any lighter. Similarly, a W12 would be a lot shorter than a V12 and not much wider but it'd probably not weigh much less (if at all). And a flat engine would weigh about the same as a V engine even though it's the same length but wider. This would require some balancing but again it shouldn't be too hard.
Fuel type modifier and Induction modifier would primarily be there to stop turbo's and DOHC from making your engines weigh way too much. Strapping on a couple of turbos might make your engine need a bigger engine bay but they only add a few kg's.
Weight slider multiplier would behave the same as the length and width ones. Far left wouldn't increase weight at all, far right would increase it by 25% ish.


So, with the above examples, we design a I6, a V6 a flat 6 and a V12, all with DOHC, Natmo and 86mm bore and stroke with lengths and width sliders far left (x1)
We would end up with the following dimensions:
I6: L 769.2mm (30in) W 279mm (11in)
V6: L 459.6mm (18in) W 365mm (14in)
Flat 6: L 459.6mm (18in) W 451mm (18in)
V12: L 769.2mm (30in) W 365mm (14in)

And a couple of other layouts with the same volume (and valve train and induction) as the 6's above:
A 3L I3 with sq B&S (108mm): L 538.8mm (21in) W 312mm (12in)
A 3L I8 with sq B&S (78mm): L 898.8mm (35in) W 267mm (11in)
A 3L V12 with sq B&S (68mm): L 639.6mm (25in) W 320mm (13in)

Again, these numbers need tweeking but it looks sensible (to me) and it means bore and stroke are only effected by the bore and stroke sliders and the lengths and width sliders stay relevant because they determine how much effort you've put into keeping your engine compact.

(02-16-2015, 02:44 AM)Frankschtaldt Wrote: [ -> ]The current system for bore and stroke and calculating engine sizes is weird and produces a number of odd results. Like V12's being wider than they are long or a 3L I8 being the same length and width as a 3L I3 (or very close too it).

These are only the case if you choose to make them odd shape. I don't agree that it's weird if increasing bore increases width, or if increasing width increases the maximum amount of bore...

Quote:Remove the effect length and width have on these values. The bore slider has access to the full bore range and the stroke slider has access to the full stroke range (from 40mm all the way up to 260mm or whatever it happens to be that year). No, this wont make length and width sliders irrelevant, keep reading.

This would break just about every other rating in the game, also there will be noticeable price difference between a 40mm engine and a 120mm engine. This would break the game balance for engine sizes.

Quote:The bore and stoke are now used to calculate the minimum engine size, along with a few other factors. Now, the lengths and width sliders determine how much effort you've put into making the engine as small as you can for the displacement you've chosen.
These equations will also eliminate the previously mentioned anomalies as well.

Having the length slider all the way to the left would make the engine as short as possible (so, multiplying the above equation by 1) while sliding it all the way to the right means you've not invested any time in reducing the size of your engine at all so it would multiply the length by 1.25 (or, maybe a bigger number if you think that's necessary)

You would still have the same issue of V12's possibly being wider than long IF the user moves length to the right and width to the left. That doesn't solve your original issue.



The current issues with width/length is due to me moving from slider values to direct specs due to the complaint you had with high torque. I have not had time to balance it out. That being said, it does need some tweaking, but I don't agree with your system above. Width/Length will effect min-max bore/stroke. I will not give you access to the full range of sizes. As for removing bore/strokes effect on engine size. Even your formulas above do that by creating a minimum engine size for the bore and stroke. Same thing our system does. If you had width/length sliders at 50%, and you changed bore/stroke, then it'd be at 50% of your new minimum size. So in effect, your system does the same thing, except width/length does not change the range bore and stroke does.

Our numbers are unbalanced because I had to chop out chunks of code. But in a nut shell your concepts are nearly the same.

Need to increase the size a wee bit, but see, just a balancing issue.

Now I just need to switch weight from bore/stroke to width/length, due to the fact that width/length no longer increases bore and stroke as it used to.

Ok so I went through the stuff you suggested, most of your formulas and my formulas match.
I fixed the issues with the width/length that we were having due to fixing the torque issues caused by w/l sliders in 1.17.5.1

The results I believe are much better now. Although I still have bore/stroke max/min values based on width/length. As personally I think it's a better system, gives more importance to the width/lengths sliders, and balances out costs. Try it out, tell me what you think.

(Also remember a direct Bore/Stroke system is coming with this GUI update.)

The suggested way of calculating width and length seems to make it more cumbersome to fit the biggest possible engine into a smaller chassis. Not sure that I'm swayed by it.

I've been searching high and low for dimensions of some engine families that I know have been produced in multiple layouts (such as BMW's M30 I6 that was based on it M10 I4 and GM's V6 that was a cut down V8 etc) so I can actually discuss this from an informed standpoint but I can't find squat.
So, I'm going to preface this by saying this is all based on my understanding on how stuff works. Which is more informed than your average, but not as good as a mechanic or engineer.

The equations are definitely behaving better than they were but they still don't feel quite right.
I think your engines gain too much width as they gain cylinders and not enough length. Playing around with a 1930's game, making a bunch of different engines all with the same (3.5") bore and stroke. I found that in every case, adding another 2 cylinders to the length of the engine only added 7" to it's length. Exactly two bores, not allowing anything for the width of the cylinder walls or the cavity for cooling water to pass between them. This is an easy fix I imagine, just a multiplier tweak somewhere.
Width wise, the I8 I designed was 75% wider than the I2 and 40% wider than the I4. The I6 was 20% wider than the I4. No doubt there would be some gain in width due to increased complexity and need to brace against greater torque across a longer crank but this seems way too much.

All of these examples are for inline engines but they all behave the same.

In short, the length gain for increasing cylinders need to be increase while the width gain for more cylinders needs to be decreased.

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I kept mucking around and with a 4" bore I was only gaining an average 3.75" length per cylinder but with a 6" bore I was gaining 8" per cylinder and an 11" bore I was gaining a whopping 37.75" per cylinder!