02-20-2015, 12:30 AM
(This post was last modified: 02-20-2015, 12:37 AM by Frankschtaldt.)
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.
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!
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.
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!