Ok help me wrap my mind around this....
it's been standard advice for eons that if you upgrade turbochargers or add boost, valve springs need to be stronger to hold valves down against the increased pressure.
I've heard this and repeated it before, without ever doing it.

Here's the thing I can't figure out...
If were saying that the pressure in the intake manifold or exhaust side is getting high enough to lift the valves, that could only be possible if it were higher than stock pressure (to exceed the spring rating), but also that the other side of the valve pressure doesn't increase. See what I'm saying?

For explanation without proper numbers, pretend we have a valve with the same surface area on both sides and 100lbs of force closing it, so 100 pounds of pressure would lift it; if the cylinder pressure is nothing, and manifold pressure exerts 100lbs of force, it will open.
but it will also open if there is 400lbs from the cylinder and 500 from the manifold because the 100 lbs of force is still there.


So, if we increase intake or exhaust pressure say double or triple, how would this ever cause valve float?
the only way it could, is if the manifold pressures increased, but the cylinder pressures remained stock, which is impossible.

Lets say a hypothetical diesel engine, runs 30psi of boost and 30 psi of back pressure WOT. There would never be less than 30psi in the cylinder. If we add fuel and more boost to it, and double the numbers to 60/60, now there is always at least 60psi in the cylinder. So yes there is more pressure on the back side of the valves, but there is also more in the cylinder too.

Is this thought process about upgraded valve springs a plan from increasing rpm that the reasoning just got forgotten about and people don't ask questions?

Am I missing something? Is it too early? Haha

 

I can't help with an explanation. All I can do is provide my experience. I installed a set of Comp Cams Beehive valve springs when I did my turbo and injector upgrade but I didn't set the installed height. There weren't any shims under the factory valve springs so I didn't think I needed any shims under the upgraded springs. In turn I didn't have the proper spring rate after I completed my installation and ended up having some undesired rocker arm to pushrod contact and broke a pushrod. That's when I learned about setting the installed spring height. So now I have the spring height set correctly, a new set of 7/16" pushrods, and since I was in there again a set of Track Tech head studs. I don't know for sure what caused the unwanted rocker arm to pushrod contact I just know it happened.

 

unwanted rocker arm to pushrod contact stems from not collapsing the lifters

If you did only your valve springs, valve stem height wont change unless it wasnt up (valve closed) to begin with

its possible you had such a weak valve spring and the valve was pushed open by the extended lifter, then adding the spring lifted the height and rod is too big now to do its job and bent


40 PSI max boost x 2 square inches aka 1.6 diameter valve = 80 PSI minimum spring pressure needed to keep valves closed under max boost