I was reading an old article in SCC about a bov test. I'm having trouble understanding the concept of "crushing the top of the cap assembly down a few millimeters to raise the internal spring rate." Wouldn't crushing it, shorten the spring and make it easier to compress......or do i just have that bass ackwards and it obviously makes it harder to compress????
yea, you have it a little mixed up...
you need to understand EXACTLY how the BOV works...im sure you have enough of a concept of how it works so ill go from there....
when there is too much pressure in the charge piping, it pushes up against bypass valve...when this pressure is too high (set manually or electronically), the spring is compressed enough to open the valve (thus the cool noise)...
now, crushing the cap (the actual part that opens up enough to let air through) decreases the total distance of the spring, making it closer and shorter together....so if its shorter, and closer together, the spring and the valve must also both travel farther to fully let the valve open up...
another analogy...
your OEM springs...long, big, low spring rate
lower springs...shorter, not so big, much higher spring rate
compressing the spring makes the spring rate higher
this is what the concept is for the adjustable BOVs you find.
you can tighten or loosen the spring on the top to "dial" in how much tension is
against the valve.
