heavy duty valve springs

[Rancher2005]

I had thought that heavy duty valve springs were meant to keep the valves from floating at higher rpms with more aggressive cam lobe lift or durations. If this is the case, would the extra pressure that they apply add more resistance to the cam lobes and thus excess drag on an engine? I'm sure I am overthinking it quite a bit and am also confident that the drag would be negligable compared to the performance gained by the cam. I just enjoy discussing engine theory.

[440exnacsracer]

the extra friction is typically negligable. stronger springs can actually increase horsepower slightly if your stock springs are allowing the valves to float.

[JasonP]

Ok.. I can see where this is going.
Well when the exhaust cam is coming off the intake is starting. So right there you have one lifter pushing down on the cam and the other pushing down on the valve. So one is actually trying to push the cam backwards and the other foward so it's almost like there off setting each other in a sense... .really though your over thinking this. There's almost no sense to this because it's something that you will never be able to change. Not unless you would go with pneumatic valve train.
I agree though that HD springs put more load on the cam but I wouldn't say excessive and it's not HP robbing and if it is it's so minimal that it doesn't matter.
Here's a fact for you though... about 45% percent of the engine drag comes from the piston rings. This is why many engine builders will use lighter thinner rings.. well they do this to because they run higher rpms as well but you get the idea...

[Rancher2005]

Originally posted by JasonP
Here's a fact for you though... about 45% percent of the engine drag comes from the piston rings. This is why many engine builders will use lighter thinner rings.. well they do this to because they run higher rpms as well but you get the idea...
good to know. Now my next question is... in any way would one notice the heavy duty valve springs for instance when decelerating? It seems to me that "in theory" if there is more resistance it would almost feel like more compression.

[2muchquad]

no,they can lead to increased rocker arm wear though.They will also beat up your valve seats if you dont keep them adjusted.There is no free lunch:(