A demonstration of the firing interval of an I5 with the crankshaft phased to create a perfect fifth between cylinders 1,5 (firing at 360º intervals) and 2,3,4 (firing at 240º intervals)
The firing order of this theoretical engine is 1 4 5 2 3, but it was supposed to be 1 3 5 2 4 (which would sound exactly the same) for symmetry, not sure how I missed that but i'm not making the video again.
Firing intervals are 0º, 180º, 360º, 420º, 660º for either firing order.
This crank configuration should have a smaller rocking moment than an even fire inline 5 cylinder engine, but second order shaking would probably be bigger/worse. I could model it crudely but that is getting way too far into the weeds.
An engine using this crankshaft would need primaries 1,5 merging into a tailpipe and primaries 2,3,4 merging into another tailpipe for maximum effect. This could make turbo sizing tricky.
I had the idea for this configuration a long time ago but was putting too much thought in to the relative positions of the outer two and inner three crank throws, after making the three engines synchronised program/video I realised it didn't have much impact on the sound.
