1.8t

Did some searching, but the results still seem a bit unlcear. With regards to durability, how are these valves? In searching this site, it appeared that the stock valves were fine for n/a applications, however for F/I and Nitrous applications, apparently they were not the application of choice. Reason I am asking is because I have heard of C5Z's breaking the valve off the stem before due to the 2 piece welded design. I am worried about cam'ing my LS3 because of the higher seat pressure from aftermarket valve springs. All this would do is exacerbate this potential weakness and induce failure that much more quickly. That said, what do you guru's know about these valves? Is the construction process the same as the C5Z's valves? Have you guys ever heard of the C5Z's breaking their hollow stem valves? If these valves are crap, I will yank the heads and put new ones in along w/ a CNC job when I decide to cam the car. Optimally, I would just like to cam it and be done but that 2 piece welded design has me worried.

black_z

iTrader: (4)

I wouldn't worry about it for an NA application. Cylinder pressure is quite low compared to a boosted or sprayed application.

Richard@WCCH

iTrader: (3)

You're correct about the hollow valves handling NA duty. They don't play well with FI applications though. The factory valves are well built, but very thin in critical areas. We've not seen any failures in NA engines........yet.
One thing you can do to minimize the hammering on the valves is to choose lazy cam lobes. The performance loss is minimal and valve train stability stays high. The heads will carry nice hp due to the large high flowing intake ports.

Good luck,

Richard

1.8t

Good deal, I really appreciate the help guys. Richard, can you give me some examples of some cams with some gradual ramp rates?

Ragtop 99

iTrader: (7)

Comp XE lobes are relatively mild, at least in comparison with their XER, XFI, or LSK lobes.

See5

iTrader: (53)

We use them with PSI 1511 behives with great success. The valves only weigh 89 grams vs 108 for L92 intake valve.

Richard@WCCH

iTrader: (3)

Excellent point. Comp has a number of lobes listed in their master catalogue that they can girnd onto a LS cam core. You'll need to check with them when ordering.

Richard

GIGAPUNK

iTrader: (2)

I'm purposely bringing this back from the dead. Richard, 4 years latter have you still not seen an N/A Stock LS3 intake valve failure on a cammed car?

ohiomike

iTrader: (1)

wtt my l99 non hollow valves for your hollow valves

25k miles

I am ls3'ing my L99.

litle88

iTrader: (20)

Go for it! Money well spent!

litle88

iTrader: (20)

Not that I'm aware of sir, mods in my sig and I know a few others that have some sort of similar setup and no breakage (yet) knock on wood lol