LS3 Compression
Former Vendor
Joined: Feb 2004
Posts: 9,615
Likes: 13
From: Burlington NC
I would rather use a valve that isnt so sensitive to the bad things around it. Lots of engines run the heavier stainless 2.16 valves out to 7200 with no instability so why bother with hollow stems? Additionally, at some point we have to say, "there are some good engine builders still having failures so (at some point) not everyone is an idiot and the part may actually be a bad idea", rather than blaming other things for a poorly designed valve. I havent heard any fables of stainless valve heads breaking off when there was no other failure such as a timing chain or valve float. Just about all the time there is an issue with a stainless valve I hear it bent, not broke into two peices.
The heavy vs light hollow valve will be debated for years. I personally really like the hollow valves. They run cooler, don't require as much spring which is easier on timming chains, seats, valve angles, guides, and etc. Sprint racing I don't see any reason not to run the lightest weight valve train you can. I bent valve, is just as bad as a broken valve. A DNF is a DNF no matter what. The guys running T-1 and simular showroom stock classes can't do anything to the valves. So they are kinda stuck with what GM has given them. Endro racing is a different ball game all together. I personal wouldn't run a heavy valve in anything that is going to be at high rpm all the time. WC had couple loop holes to run different valves, most are running the lightweight hollow stems. You haven't seen a ls engine hump unless you put that 106lsa cam installed at about 103 degrees. At 7400 rpm or more it is a sound that most haven't heard.
Street applications can go either way valves. Any stock piston running a 234 and up camshaft like Spin said is getting close on piston to valve. My best suggestion is to increase that distance by running a smaller camshaft. Of course this would mean less power. We are very shy when it comes to big cams in street applications. Long service life and good street manners is what 90 percent of my customers want. Even the other 10 percent that spend all their time at the track. We aren't building crazy compression and camshafts. But when it comes time for green flag racing, Look out.
Why did GM put the lightweight valve in there??? Well it's a big valve, close to the piston. With a valve seat that maybe can't take the stress of a heavy valve running higher pressures. Warrenty issues like the trucks out there in NY, it's easier to replace the engine then it is to pull heads, rebuild, and reintall.
Stainless valve are pretty damn strong, and I have only seen one break off. But I have seen cast pistons turn into a million peices once the SS valve hits it.
Spin, I saw that you just flycutted the intake side of the piston. How close are you to the exhaust valve? The exhaust is the one that requires almost double what the intake does for piston to valve clearance. Just curious is all
Randy
Thread Starter
Team Owner
Joined: Sep 2003
Posts: 43,084
Likes: 33
From: Raleigh / Rolesville NC
You haven't seen a ls engine hump unless you put that 106lsa cam installed at about 103 degrees. At 7400 rpm or more it is a sound that most haven't heard.
Hearing LG, Tony Gaples, and the Wheeler vettes fluy by is UNBELIEVABLE.
I will see if I can up load over the weekend
Edit Dang video format is too big.
Last edited by AU N EGL; Oct 11, 2008 at 07:46 AM.
Former Vendor
Joined: Feb 2004
Posts: 9,615
Likes: 13
From: Burlington NC
Randy
