Did GM reinvent the roller lifter for the LS1 or are they effectively the same since the L98?

 

As per Hib Halverson:

"Gearhead’s View of the Valvetrain

The LS1 camshaft is machined out of a steel billet and is rifle-drilled to reduce mass. A camshaft sensor, necessary on engines with SFI for the PCM to "know" where the engine is in the firing order, is just ahead of the rear bearing journal. Compared to LT4, the LS1 cam has larger bearing journals, all the lobes have bigger base circles and lift is less, especially the intakes. Going to the larger base circle and less lobe lift reduces valve train loadings because the acceleration rate is lower.

The new engine’s rpm limit is about the same as that of a LT4. That, along with the lower valve acceleration rate, allowed many valve train parts to have less mass which permitted use of lower tension valve springs and that lessens the impact as the valve hits the seat on closing. Valve train noise is reduced which, according to John Juriga, was a big goal of the Gen III program. Specific to Corvettes, maybe that is not all that great an idea. The Corvette Mystique partially grew out of mechanical lifter camshafts. Give us that’ 92 LT1 valve noise, thank you very much.

The valve lifters are the roller hydraulic variety and are the second of the two pieces that carry over from the Small-Block. The centerlines of the lifters, pushrods and the valve stems are parallel. The Small-Block had them at angles to each other. These angles caused side loading which accelerated valve guide and lifter bore wear and increased friction. The LS1’s "in-line" valve train reduces friction and allows some parts to be made smaller and lighter.

Bet ya saw those fancy roller rocker arms, too. Some Corvette owners are gun-shy of roller rockers because of the fiasco with not one, but two recalls during MY96 of a large number LT4s due to rocker arm failures caused by roller tip pins falling out. Ironically, the second recall affected all the cars of the first. Is that, like....a "re-recall"? Sorry, but we couldn't resist that. We know customers told not to drive their LT4s because of an initial shortage of recall repair parts saw little humor in that situation.

For those with such roller rocker "phobia"; LS1 is good therapy. Its rockers are investment cast steel rather than aluminum and the roller tip pins are held securely in place. The rocker arm ratio is 1.7:1 vs. the LT4’s 1.65:1 and other Small-Blocks’ 1.5:1. The higher mechanical advantage of the LS1 rocker amplifies the smaller lobe lift such that valve lifts for an LS1 are: .472-in. for intake and .479-in. for exhaust compared to the LT4’s .476/.479 lifts. Chevrolet refused to share additional valve timing data with us.

John Juriga’s last words on the LS1 camshaft were, "We didn’t go more aggressive on the cam, so at this point, the engine has a lot of potential. First time out, we could meet our target with a camshaft that is conservative."

This might indicate that there will be a lot that performance tuners will be able to do with this engine’s camshaft."

 

thanx

 

so why would compcams need to deveop a new solid roller lifters? If the old hydraulic rollers worked, why wouldnt old style solids? Or is it just a ploy to charge twice as much?

 

Newly available, stronger, lighter material perhaps?

 

I bet it has something to do with the locking bar on the aftermarket solids. Either that lubrication. Failing those, I am saying scam.