Much like the more common Long Jump Attack, Long Helm Splitter (LHS) is a technique that gives Link greater horizontal speed than a standard Helm Splitter. This can be done by initiating a Helm Splitter nearly immediately after the enemy has been stunned in a way that gives the Helm Splitter prompt. While the window for LHS is normally occupied by Link finishing the Shield Bash animation that leads to the Helm Splitter prompt, it becomes accessible if either the enemy runs into the Shield Bash near the end of its animation or the Helm Splitter prompt is brought on by another means, such as using the boomerang or clawshot to stun a lizalfos. (Note that lizalfos are the only enemy that give a Helm Splitter prompt when stunned with an item instead of Shield Bash.) Helm Splitter height is not affected by LHS.
Link's speed during a normal Helm Splitter:
With LHS, the speeds on frames 1-13 are multiplied by a value that depends on how many frames after the enemy was stunned the LHS began on. The maximum speed multiplier is at least 3 and may depend on Link's distance from the enemy as well. (More research needed.) The speeds on frames 26-41 are unaffected by LHS.