The K series installation was designed with a shallow sump to fit under bonnet. The consequence being a low shallow volume of oil which was susceptible to aeration - tiny bubbles suspended in the oil. This was amplified buy the high lateral g forces generated by the cars. The aerated oil would circulate to the hydraulic tappets acting as a spring the valves bounce resulting in loss of control, the valves would touch the pistons bending them, eventually with a bending fatigue the valve heads would drop off resulting in total engine failure. The tiny bubbles suspended in the oil need to be burst or be purged . Air is removed / bubble burst if the oil hits a solid surface / object ie baffle, foam, block or sump.
The sign off test devised by Caterham for a 1400 Supersport was 1st gear (5 speed box) max revs three figure of eights as fast as possible brake to a stop idle the engine and listen to see if the tappets rattled / aerated. The foam arrangement gave the required results.
Further development mainly for track competition resulted in the Apollo tank, solid tappets, purple pump dry sump leading to much higher performance gold pump dry sump package.
To run an Apollo with the increase in oil volume and the centrifugal purging of air from the system would probably negate the use of the foam.
I have run the same foam for some 27k miles 13 years without issue. There have been failures of the foam leading to engine failure possibly due to :-
1) bad batch of foam material
2) fuel contamination
3)Oil compatibility / contamination
4) engine temperature etc.
There is no clear reason as to the cause of failure of the foam.
Hope this helps
Dave