did Dyna's have smaller oil tanks--why the xtra long filter?

[1982fxr]

So I noticed that the dealership had extra long filter that I understand were for 90's Dyna's or something?  I mean they are like 4 times longer (same width) than my old FXR filter.  Why?  Did they have a smaller oil tank and that's where they had to make room for more oil or something?

[JBarrettB]

Yes, volume of the system.

JB