speer13

I have a question..if you take the basic calculations for spring rates, coil bind, seat pressure etc. for an LS6 valve spring it seems they are underrated for lift? I know how aggressive the lobes are will affect this as well but I am wondering if the max lift advertised is more for longevety from GM?

By my calculations at the installed height of 1.8 using a minimum coil bind clearance of .100 it leaves enough room for .615 lift, granted the seat pressure isn't probably good enough for a larger cam.

But there seems to be a lot of people jumping to the PAC springs for increased seat pressure and if my math is right you could shim the LS spring for an installed height of 1.74 increasing the seat/open pressure by ~22-23 pounds for a final seat pressure of 112 and still be able to accomodate the .570 advertised max lift with a coil bind clearance of .095 inches which should be more then enough for street cars... the only down side I see is spring fatigue but building a car with power I don't expect a 100,000 miles before I need to replace parts.

I am in the mindset for holding boost better with the LS6 spring and using say an LS9/LS6 cam

Gunslinger09

The material the springs are made from has a lot to do with the lift rating of the springs too. Most of the aftermarket springs are made of a different alloy than the stockers. I suppose you could do it for a while with an LS9 cam being the Ls6 style springs are what they use stock, but that's with the light weight valves.

TurboBuick6

iTrader: (2)

The processing of the OE springs were not ment for a higher stress enviroment i.e. closer to bind, valve accelration, ect. This is where your main difference in OE and aftermarket come into play. Also like mentioned more than likely the alloys are different too. Need to remember OE is all about margin and profit 100%. What ever process and material it takes to get a good enough pass test rate is what is used.