Power & Springs

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Mar 24, 2011 | 11:14 PM

Paul57

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From: Frozen Tundra, WI

Power & Springs

How much horsepower loss is there by going with a heavier spring pressure? I was looking at PAC and PSI springs that have 130 seat pressure but one has 326 open and the other has 370 open (625 lift). Is the difference mostly theory/speculation or is it noteworthy?

Mar 25, 2011 | 12:18 AM

NVR_SPDS

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I dont think its spring pressure as much as it the weight of the springs. Like comparing a single behive, to a set of duals, the duals have more mass to move so they are heavier.

Mar 25, 2011 | 12:28 AM

ls1 1990 VN

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From: Auckland, Nth Is, New Zealand.

I changed from Dual Patriot Gold & small lift cam to PAC 1518 behives & picked up 500rpm, as the Patriots wouldn't allow engine to rev past 6200rpm

Mar 25, 2011 | 10:26 AM

Paul57

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From: Frozen Tundra, WI

That seems like a good indicator.
Do you know what the duals and the 1518's were rated at (at the same lift point)??

Mar 25, 2011 | 02:15 PM

ls1 1990 VN

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Quote:

Originally Posted by Paul57

That seems like a good indicator.
Do you know what the duals and the 1518's were rated at (at the same lift point)??

Both at .650

Mar 25, 2011 | 02:40 PM

Paul57

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From: Frozen Tundra, WI

I was referring to the difference in spring pressure between the duals and 1518s, at the same lift??

Mar 25, 2011 | 04:04 PM

DONAIMIAN

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There wont be a difference in power output from the spring. Keep in mind when you have one spring pushing on the front side of one lobe, there's another that putting pressure on the back side of another lobe. The sum of all springs cancel each other out. The only power to be gained (or lost) is due to the springs ability to control (or not control) the motion of the valve.

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