JIMS SVT

iTrader: (3)

Will a Ls3 hollow stem valve turned down to a 2.04" in my tfs215 heads be OK with my cam? Its a 239/244 .674/.653 111+4 Martin Smallwood spec cam. Has .700 PAC springs shimmed. I was just worried about the valve possibly ciming apart with such a big camshaft.My FRC made 468/415 on the dyno with 500 miles on it. Last time to the track it went 10.78@129.64. It has a few thousand miles on it now. Just looking for a little more out if it.

axe murderer

iTrader: (3)

I get my stuff done in MI, the guy I go to does a lot of CNC LS3 stuff as well as some testing for GM and he tells me stay away from them in everything but mild combos.
I usually supply my own valves so it's not like he's selling me anything.
They usually take them out & use Ferrea or Manley stuff which also flow better.

JIMS SVT

iTrader: (3)

They have ferrea valves in them already. I was trying to get the weight down on the valves and get the power to not look so flat.

speedtigger

iTrader: (16)

I have the LS3 valves in my latest build with 160# seat and 460# open at .660" lift to 7500 RPM. I have talked to several other people with similar builds who have not had failures.

JIMS SVT

iTrader: (3)

I'm around 170/469 on mine.

Martin Smallwood

iTrader: (2)

I have a GM LS3 hollow stem intake valve in my turbo motor. Currently it has roughly 190# seat pressure and 480# open.

JakeFusion

iTrader: (7)

I run a turned down LS3 valve in my heads with a 160/400 spring and plan to run a hollow-stem in my next heads with a 170/480 spring.

A.R. Shale Targa

iTrader: (2)

Manley does make hollow stuff also

thompson

iTrader: (4)

We have ran many aggressive combinations utilizing the factory LS3 intake valves without issue.



Aaron @ Thompson Motorsports

DavidBoren

This is my first time seeing anything negative about the ls3 intake valve. I have heard about the ls7 valves breaking, but nothing about the ls3 hollow stems, until now, obviously.

There's no recall of the ls3 intake valve. And there's LOTS of happy ls3 owners driving their cars everyday with the stock valves... Quite a few of those happy stock valve using ls3 owners are boosted, as well... And more than one of them are beyond what could be considered a mild build, for sure.

I would run turned down ls3 hollow stems in a heartbeat.

axe murderer

iTrader: (3)

Ive seen guys on other forums say the tips came off of LS3s & a few say the heads came off which would make me believe they're a 2 piece welded valve like the LS6s but the internet experts seem to like to blame the springs.

LS6 & LS7 had issues so GM couldn't get it right on the top of the live Corvettes but did on the LS3s?
You guys have more faith in GM than I do, I've been offered them for free & didn't want them.

IIRC aftermarket hollow stems are 1 piece stainless steel & nobody can argue they're not better or flow better.
So how much do you save by the time you buy LS3s & get them cut down compared to buying Ferreas?

KCS

iTrader: (20)

Well, I havent personally seen an LS3 valve fail, but the stock valves aren't designed for some of the abuse people put on their engines so it should be no surprise to see some instances of failed valves. It doesn't mean it's a bad valve, you just can't be a dumbass and set them up with really stuff springs and stupid aggressive lobes then expect to turn 8,000 RPM everyday on your way to work.

JakeFusion

iTrader: (7)

That's my kind of commute to work.

DavidBoren

9 times out of 10, it's the Indian, not the arrow.

GM did well designing those valves and they work perfectly for their intended purpose. As previously mentioned, it is no fault of the valves when someone pushes them beyond their original intent.

Oem parts that happen to survive when pushed hard in performance applications are relatively rare. It's why these 900hp junkyard 4.8 builds get so much attention. Because it shouldn't work, but it does. However, nobody judges the 4.8 as a poor design when 30# of boost scatters pieces of the engine all over.

JIMS SVT

iTrader: (3)

Anyone happen to know the weight of a ferrea 2.04" stainless valve? Looks like the ls3 2.04" hollow stem is 83 grams now.

NHRAFORMULA00

iTrader: (2)

I spin turned down ls3 valves to 7k, over a 150 runs on this motor. 190 seat and 450 open. improper setup is what beats up valve train.

JakeFusion

iTrader: (7)

2.04 is like 108 or 110g IIRC?

JIMS SVT

iTrader: (3)

That's what I thought they was. Got my new valves yesterday. They are 83 grams.

Exidous

iTrader: (11)

I've got the Manley hollow and they are about 92g and a 2.02" valve I think. Don't remember what the Mamo220's are. They are a little heavier than the LS3's but stronger for sure.

Ernie W

iTrader: (1)

I've been wondering myself. I have a set of L92 heads for a iron 6.2 build. I plan on replacing the intake valves because one is slightly bent. Not sure if I should pick up GM LS3 intake valves, or go with Manley or Ferrea valves. I'm unsure of the mileage on the heads so I'm wondering if I should replace exhaust valves too. I have a BTR stage IV LS3 cam kit with .660 dual spring kit with titanium retainers.