In simple terms when you start to build an increase in horsepower the crankshaft wants to kick itself out of the block. The only thing holding you crankshaft in place is the main caps and your hardware. With each conventional cap typically registers or positions via a shoulder on each side (outside) of the main cap.  That is, a conventional engine block typically has a recessed channel machined to a width substantially representing the shoulder-to-shoulder distance of each main cap.  The cap intimately fits within this channel and thereby is positioned or registered. 

The new Bessel Register ™ Splayed Cap (U.S. Patent # 7322750) design alleviates the common bearing fatigue and destruction of crankshafts. The Bessel cap’s are an improvement by not only having more cross sectional strength, but the real advantage is the ability to lock the cap into the block and eliminating the ability of the cap to move inward and causing out of roundness and cap chatter. Simply put, it is all about stability and tying in more material. This design improves reliability in highly stressed racing engines by locking in with the block. It also reduces distortion of the main bearing bores by increasing the cap’s resistance to closing up under high loads.

See how the cap is locked into place and can not close up under high loads.