02-16-2015, 02:44 AM
(This post was last modified: 02-16-2015, 03:10 AM by Frankschtaldt.)
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.
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.