Can't live without smoky bacon!
- Apr 15, 2006
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- Sth Auck, NZ
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- HSV VS Senator, VX s2 Calais S/C
You need to remember that GM have peak efficiency and a warranty period in mind when they design engines. Springs only have to be strong enough to control the stock valve train at stock engine speeds and last long enough to get through the warranty period. Any extra weight in the spring just reduces efficiency and fuel mileage. 90% of OEM engines will hardly ever go past 3000rpm in their daily commuter lives which a stock spring will handle just fine for many thousands of miles beyond the warranty period.Stock rockers are cheap cast numbers that barely fit the engineering bill in performance terms. Same as the springs (they are at the operational limit even with the hollow intake). Question marks hang over long term reliability of stock spring / valve / rocker combo, particularly under heavy duty or upgraded operational range / output.
Yes, fully encased bearings and shaft mounts are superior to the weak cageless dangerous stock rockers, and the reduced friction at various loads (power and economy) is measurably better with the more advanced geometry.
Consider the benefit of more volumetric flow upgrading to 1.8rr modifying your effective cam timing without spending a few thousand. Any prospective new cam beyond that can utilise the 1.8rr geometry per LS7 and Gen V and mine to result in less cam face / lifter roller wear.
On the other hand there is zero advantage in sticking with 1.7rr apart from fitting three bolt older cam designs; no advantage sticking with springs at their limit, and lighter stronger pushrods help to deliver more control, particularly over stock peak (5700). I definitely would not be revving an LS3 with stock upper valve train near the factory rev limiter!
BTW, I do like PAC springs and high ratio rockers. Not many mild cams make full use of a stock or mildly ported heads. Even if you get slightly more lift than the peak flow point, as long as the flow doesn't become turbulent you will still make more power because you have more average lift which means more average flow (the all important area under the curve thing).