The year of the three. (126 hp per liter)

[ciderbarrel]

I hope someone here can teach me a thing or two about engine design, because I would like to know WHY 3 cylinders is better. I honestly do not know and I want to learn why. I figure that total displacement should be more of a concern than cylinder count.

All things being equal (if possible), which would be more fuel efficient: an I3, I4, I5, V6, or V8 2.0L engine? What about the same but the volume was 0.9L? 4.6L?

Is power tied to bigger cylinders and fuel efficiency tied to smaller ones?

I know the stroke and bore have a huge impact on an engine so for my examples, just assume they all have the same stroke, if that helps comparing them.

[niky]

It's notoriously difficult to make certain engines a certain size in certain configurations. When making small engines nowadays, manufacturers need to include a whole lot of stuff in the cylinder head. Space for variable valve systems, extra spark plugs and direct injection injectors. By lopping off a cylinder and making the other cylinders bigger, you get more combustion chamber real estate to position everything.

And then there's the whole pumping losses thing. Less moving parts makes for less friction. Of course, you could power small cars with one liter one cylinder motors, but the resulting vibration and harmonic balance issues would make them very crappy motors... not to mention the difficulty of turbocharging such a beast.

[cRiPpLe_rOoStEr]

Originally Posted by ciderbarrel

I figure that total displacement should be more of a concern than cylinder count.

The # of cylinders has an important role in other matters, such as the R/L ratio, power and torque curves, and also weight-saving reasons. We can also take into account the energy expenses required to produce an engine, which are lower when there are less raw materials to be processed and less moving parts to be machined

Is power tied to bigger cylinders and fuel efficiency tied to smaller ones?

Actually, from what I've seen in practical with engines from different displacement ranges, bigger cylinders in a smaller # usually lead to lower revving bands, altough a broader torque curve is easier to sustain, while smaller cylinders in a bigger amount usually lead to higher revving and more power, altough any eventual increasement in torque doesn't have the same proportion as the power increasements, plus getting more concentrated in higher RPMs.

[ciderbarrel]

Originally Posted by cRiPpLe_rOoStEr

The # of cylinders has an important role in other matters, such as the R/L ratio, power and torque curves, and also weight-saving reasons. We can also take into account the energy expenses required to produce an engine, which are lower when there are less raw materials to be processed and less moving parts to be machined




Actually, from what I've seen in practical with engines from different displacement ranges, bigger cylinders in a smaller # usually lead to lower revving bands, altough a broader torque curve is easier to sustain, while smaller cylinders in a bigger amount usually lead to higher revving and more power, altough any eventual increasement in torque doesn't have the same proportion as the power increasements, plus getting more concentrated in higher RPMs.

That does make sense to me esp in motorcycle terms. My 250 Ninja (parallel twin) was really high revving, but my old 03 1700 Warrior (v-twin) was very low revving. I don't think I ever took it over 3500 rpm

[wdb]

Originally Posted by ciderbarrel

I figure that total displacement should be more of a concern than cylinder count.

Well then, do I have an engine for you!

http://www.youtube.com/watch?v=mutb7KgA9NM