Spanks. That guy again spoken about on another thread..... BBC valve spoken on can be looked at as a Ls valve @ a higher rpm.. quick search 😂 bout 30 seconds. Google search of:
solid valves vs hollow stem yellowbullet

https://www.yellowbullet.com/threads.../post-32457610

 

Smoking and a question... I feel sorry for the question 🤣😂

https://www.yellowbullet.com/threads...valves.329547/

 

This has been an informative discussion and what I've taken from this is that from a performance standpoint the titanium is King.

Question: So when is it too much spring and what dictates the size to use?

 

Titanium with a DLC is King.

I have used Titanium pistons pins with a DLC, sure they cost a lot, though it does save money when you need to add "heavy metal" in order to "0" balance a crankshaft.

 

​​​​​​Each Cam Does have a Recommendation for Springs and starting there? If you get valve float maybe Shim or go to a stiffer spring. If a builder has a weight there comfortable with and sees more weight they may want more spring?

 

This is true to a point, but people who believe stiff springs dont affect power, I say install some 200lb on the seat/500lb over-the-nose springs, install the timing sproket/gear, and simply rotate your cam by hand! Stiffer springs take power to compress. It's like the uphill/coast down hill fuel mileage debate. You'll use more fuel going uphill, than you'll save coasting downhill, equal lengths on each side.

 

Heres a better one ....think of trying to turn over a PS or top fuel car by hand...Big spring pressure vs a typical engine.

 

1. Stock bottom end ls3 including stock lifters, stage 2 off the shelf cam. Will be run day in and out until something breaks, hopefully never does.
   • I would want hollow stem factory LS3 valves here. I've always used dual springs with any aftermarket cam, ~130 seat 350-450 open seems to be the most common range for hydraulic roller spring packages. From what I've seen, this is overkill for most mild cams - single springs will work, but I like the peace of mind of having a dual spring in case one breaks.
2. Rowdy street car w/ forged 416 ls3 with short travel slow leakdown lifters, slaps harder than your mom last night stage 4 cam...will go on car show cruises, Mexico roll racing, and hits the track 10 times a year. Took the stock heads off for porting - still has the stock LS3 hollow valves. Do you change them?
   • My experience with stock ls3 hollow stems has been good, but I know some have dropped valves. With a hydraulic roller my thoughts have always been hollow stems are needed. Solid valves put extra load on the lifter which is not good for valve control and making sure the lifter isn't eating away at lift or duration. Maybe consider hollow stem stainless aftermarket in this case due to the size of the investment with the shortblock, but I might just go with the stock ls3 hollow stems still? Likely any of the 650 lift dual spring packages on the market will work just fine here with hollow stems.
3. LY6 junkyard motor (iron 6.0 w/ L92 heads), hydraulic roller with a sloppy stage 2 cam and an ebay turbo making 1000 hp turning 6500 rpm or less - Gas pedal has two positions, 0 and 30psi, but is just a daily driver.
   • Probably again..upgrade to stock ls3 hollow stem valves with some dual springs to handle the extra cylinder pressure?
4. Super clean ls3 grand sport corvette with 10k miles - medium sized LLSR will turn up to 7500, likely won't drive past 7000 much, and probably will just show off the dyno sheet and drive 100 miles a year. Just bought M311 heads and needs to pick valves. Has all other premium bolt-ons like carbon clutch, fast intake, 2" headers etc etc.
   • This one I honestly don't know - I feel like some will say solid stem, but I think a good hollow stem aftermarket is the way to go and something like a 1207x dual spring from PAC - but solid valves would save a chunk of money, and might not have any issue especially since LLSR or low shock profiles are known for being more gentle to the valvetrain. The intent of the LLSR is to be happy at high rpm, and be faster reving and a smoother engine - lighter valves all are directionally correct for those goals.

Bonus round:

• 14:1 compression drag engine and street race machine SBE ls7, LLSR cam but not too crazy - endurance type lobes for good stability and life, 7500+ rpm expected with a single plane, runs mid 8's in a fox body, but the motor only cost $10k to piece together - Might do race week, probably just a race car. The heads are off for porting - do you leave the stock Ti valves? Install Solid, hollow stainless, or expensive aftermarket Ti? Which springs?
  • My choice for my work in progress engine is to run some brand new factory Ti LS7 valves, and the "race only" PAC 1237x springs. We'll see how it works out someday. My thought is that the Ti valves aren't breaking, but some blame them for wearing out the guides. I wouldn't expect a failure caused by the factory Ti valve within the service life of the engine, ~5-10,000 miles maximum. I got a set of brand new takeout ls7 valves for cheap, and have a full set of low mile take-outs as spares.

The one that gets me are the Ti vs Stainless threads that you posted Corona - how many people are doing just fine with solid stainless valves, but is that why they're making 640hp instead of 660? Curve looks clean, engine pulls to 7500+ - but is anything being given up?

I guess I'd be curious if anyone with actual data can justify or argue that solid stainless valves (or even L92 truck valves) are acceptable in any of these applications.

Our bracket LS3 engines have had solid stainless valves and pull to 7800 and make great power with a hydraulic roller, but it is only at 7500+ rpm for a few seconds each run.

There has to be a reason why GM has done hollow stem and sodium filled valves for decades. My expectation has always been that it has to do with the hydraulic lifters, and also limitations on what they can do for a single beehive valvespring that will also live 100k+ mile durability testing.

 

If it's commonly accepted, Mark me as the second guy that hasn't heard it before! I'll bite on it, though, because if strength and durability are maintained as valvetrain weight is reduced, it's a win/win. Judging from my inquiries on forums, at the strip, and personal experience, quite a few people I've talked to seem to be erring on springs that may be 'too stiff'. That's also an engine life shortener, in ways I didn't really think about, until I saw it in my own LS7! High cam bearing journal wear occurs on street driven cars that are only taken out of their, uh, "nursery" a couple times each month. In that time, a lot of the oil drains off the cam bearing journals, while a minimum 180lb-200lb seat pressures push hard constantly on the lower half of the cam bearing insert. Kurt Urban told me it was gonna happen. He said "I'll bet if you pulled your cam out, there's no babbit material left on the bottom of the shell, only copper". I'll be damned if he wasn't right!! I could pull the cam halfway out of the block, still have the thing supported by a couple bearings, and 'wiggle tested' the cam. I was surprised at how much the cam would move up and down, far more than I expected. But it hardly moved from side to side. Cold, oil dry starts, on infrequently run engines are the cause, for sure.

 

I was running stock rocker arms with upgraded trunnions on the BR7's with .660 springs. I later installed some T&D billet steel rollers and I felt that I actually lost some performance after the swap. Gonna be swapping springs soon and I'm definitely going with PAC 1208X valve springs on this go around.

Currently a hydraulic 243/251, 115+5 LSA, 111° ICL, .661"/.633" but thinking about doing an LLSR 246/256 114.5 LSA,110° ICL with .684"/.666".

 

I have installed roller cam bearings in the "tunnel" .
This is a must with high nose pressure springs.
There is an added benefit, much better oil pressure.

 

@spanks13 your number 3 scenario is getting solid valves for me. Has GM ever put a hollow valve in a boosted motor?

 

LSA had hollow intake valves
LS9 had titanium intake valves, sodium filled exhaust valves

 

For the Thread starter....my turbo Buddy 🤣😂

 

Richard the BoostMeister....

 

DD's my new buddy and I was looking around...

Good Boost Conversation. I didn't watch but it's for my Buddy 😲

 

Love it! I like having my cake and eating it too.

 

GM lists LSA as using solid stem intake valves?

https://www.chevrolet.com/performanc...valves-springs

12605223

• Valve Size: 2.165"
• Stem Size: 8 mm

• Stock replacement solid-stem valve used in LSA engines

I'm researching some of this now, as I want to run solid stainless intake and inconel exhaust in my marine LSA build (lower RPM, higher continuous load). I acquired a set of very low hour (dyno only) factory blue-spring'd 821 heads, and will be removing what they came with to sub in stock solid SS / Inconel.

 

I didnt think the LSA had hollow stem valves either, but was too lazy to search LOL.

 

I got my info from Summit's LS engine database. It might not be totally accurate, plus GM might have changed the spec somewhere along the way.