If its not being considered it MUST be.
I meant to change my springs out after 18months but due to my new home being built i let it go, end result broken spring, damaged rocker arm , 3 lifter wheels showing signs of wear, and a new cam. About $1800 worth of damage, it could have been much worse.
The one thing id recommend is that if going solid on the street , is make sure your lifters are rebuildable, install new springs and a fresh set of lifters , every 18months
It would be great if i could make the windows in my lsx block larger so i could replace lifters without removing heads, has anybody done that successfully?
With me being in Australia, ive bought another set of lifters so in future i can have a set ready to go in while i send a set back to the states to be rebuilt. One day of serious maintenance a year and monthly checks of lash, should see years of trouble free ,tire frying, stop light to stop light enjoyment.

 

how much more spring would we be talking? we all know compressing a bigger spring will eat power.....hp loss due to a stiffer spring, is the loss greater at 8000 as opposed to 7000?

 

the limiters on these motors are under 7000, idk does the ls3 even hit 6700 factory? much lighter duty here, valve speed is much less in a factory engine. The factory hyd cam lobe is moving the valve id say less than half the speed of what a solid cam at 8000 rpm is doing. isnt this slamming the valve closed harder? im talking specifically about the ramp rate here of a big solid roller cam. just spit balling here....

 

Someone else's real world testing ...

Horsepower difference Titanium valves on Speed Talk, Raceman14 said

20 years ago I had Bill Jones cut me down some 18* valves to 2.02 x 1.60 for use in a Nascar Late-Model stock engine. We had played with the same engine for 5 years and wanted to see what Illegal valves would do with everything else the same.

It was not evident on the engine dyno as the HP numbers were the same. 421hp The revealing test was on my chassis dyno, when we put the engine back in the car with everything exactly the same the car made 37ft/# better and 21HP and was 0.4 seconds faster at Lanier National Speedway where the car had thousands of laps. The engine would also easily rev past the 6800 chip we had in the box and sent us on another tangent that we still use today to spin past the chip.

The following week we pulled the heads and yanked out the titanium stuff ( illegal ) and spent $1200 to get the hollow stem Ferreas in that were brand new at that time and almost the same cost as new Del West Ti valves but they were steel and legal.

Today our 604 crates run a hollow version of that valve and are almost as light as Ti but thier cost is only about $800 set.

As most of my work has always been on an inertia chassis dyno, I have always worked towards the fastest acceleration of the 3800# wheel is the best way to get things done even if the HP & TQ are the same. To me the static rating of an engine is a good gauge point to make sure it is in the ballpark, then all the additional work should be done to increase the acceleration factor of the engine without hurting the static numbers. In most cases both will increase but not at the same rate, because it takes the cube of power for acceleration and the square of power for static HP increases.

I am sure I will catch hell for that but it is a simple explanation between 2d and 3d measurements. A better way to gauge race cars and engines would be using thrust curves like Moto GP and F-1 folks do but that does require a time factor in the equation or an acceleration factor, not to be confused with the sampling rate of the dyno.

I am pretty sure MLR ( Mike Laws ) has referenced this with regard to his inertia engine dyno.

Seemed relevant to the discussion at hand.

 

Literally my biggest gripe with the LS engine. Why couldn't they have had the windows like aftermarket blocks.

seems like mixed results from that thread. I have to wonder on that Nascar setup if they made NO other changes, than it sounds like the prior setup was going into valve float and not setup correctly to begin with.

 

Pretty sure a hollow stem wiped out my resleeve motor this spring. I wont run them again.

 

Your not going to see anything gained power wise. The purpose of the lighter valve is valve control at high rpm. A lighter valve is simply easier on rockers, springs, locks, retainers, pushrods, even lifter wheels. I could show you piles of data from 30 years ago…if I still had it, but I don’t anymore…that showed rpm potential from lighter valves. Valve control is number one. Cylinder seal is number two. Cylinder fill is number 3, in that order. (corona gonna get me here) Simply because if you can’t control the valvetrain, or get the cylinder to stay round, it doesn’t matter how much air you cram down the hole. Of course now we are talking race engine tech here or street stuff turning 7k+ rpm.
So valve control being number one is why a lighter valve is desired, hence the want for hollow over a solid steel. Ti is great but gets brittle with heat cycles.

 

DDNSpider, Have to disagree based on engine hp performance was basically the same on their engine dyno regardless of the valves used based on what was stated. So I don't think there was valve float occurring before the light weight valves.

The stated benefits of the lighter weight valves do seem pretty amazing on the chassis dyno.

Key part of the whole post being the benefits of light weight Titanium valves were worth the risk of using hollow stem valves to mimic and stay within the rules.

 

We run the Farrea Super Alloy valves that are solid. They will handle dam near anything you can through at them. The thing that I don't understand is why everyone thinks they need 8000 plus rpm to get good results when most of the time the motor is done by 7000. Ours is set at 7400 red line. No need to even take it that high. Taylor the motor to make its power down lower so there is no need to rev it that high. As for valve springs. We have had the same springs in our motor for 5 years. Spraying the **** out of it countless passes. Over 30 dyno pulls and drive it on the street too. We have 730+ lift. and run .904 solid bushed lifters with Jessel Pro shaft rockers with .120 wall 3/8ths Trend push rods. This is in a carbed nitrous 427 with AFR 245 cathedrals that have been clearanced for 1/2 in head studs. 706hp and 616tq N/A. So it didn't break the bank.

Ive seen valves break just like that from detonation. Not saying that's what happened. If the locks and grooves are messed up on that valve it is a very good possibility.

Most of the guys on here drive their vehicles on the street regularly that in no way will ever get all the power to the ground. No Offence to anyone. I say build the motor smaller and spray that bitch when needed. These big giant motors are only my motor with a 150 shot. The point to me is longevity. **** is Expensive. We are very please with our Borowski built motor as well as several friends that have them too. Very Pleased indeed.

 

Spring pressure doesn’t affect horsepower btw - as many springs as you’re opening you have an equal number closing - they balance each other out.

 

It's fairly simple in concept, but slightly difficult in application. Here is the way I approach it. Lighter is better to a point.. Once that point is reached, go solid. Solid implies way more/complex spring to handle the load/rpm given X powerband. More spring require more "effort" to operate thereby creating a loss. Loss must be less than the gain, and also less vs gain+reliability in any given application unless reliability trumps(go Trump!) all other factors(endurance racing). That is the base theory behind it. To be honest, if you really want to learn something, study Drag Week engines. Crazy power per cube, and have to live. You learn a lot.

 

That's wrong. I understand the theory, but reality does not represent that. Have seen a few circle track motors running different int vs exh springs to gain 5+hp. Dyno proven. The overall effort does matter. Hell, I am I building a Buick Nailhead right now and actually hand lightening the cam gear to reduce weight. It all adds up, no free rides.

 

I will second that opinion.....throwing a bunch of spring pressure at things isn't the answer.

You want the least amount of spring you can get away with that will give you perfect control at the RPM you plan on using and slightly more (a little headroom is safer for over revs and missed shifts).

This is ESPECIALLY important in HR cams which lets face it represents 90% of the community reading these posts. I try and run springs in an HR that give me alot of seat pressure (so no valve bounce on the closing side of the cam as it sets the valve down) and moderate over the nose (open) pressure. More pressure than what you actually require flexes parts (so less "net" lift and duration) and is harder on the axle wheel of lifters and all the rocker arms as well. In an HR configuration it can more easily bleed down the lifter and that costs you power (once again less net lift and duration). While more spring on a solid isn't nearly as bad, it still costs power if you have more spring than you need (but is a better situation than having less than you need....that induces valve control problems).

Regarding data concerning hollow stem valves and failure rates, I suggest you reread the 468 thread and the lengthy post I made documenting all the hollow stems I have used. The actual failure rate works out to a small fractions of a single percent in a "study" that has gone on for close to 20 years and has a total sample of 8000 valves give or take. You think you wouldn't of had at least the same amount of titanium failures in a real world test that evaluated a similar quantity of valves?

How important is it to lose 20 or so grams of mass being controlled by a valve spring that is lifting the valve over .600 of an inch opening 60 ish times a second at just 7000 RPM?? Its more important than most enthusiasts (even engine builders) realize and it will not only give you more power and an extended RPM range (from perfectly accurate valve control) it will give you more insurance if you have a driveline failure or a mechanical over rev or anything unexpected that can cause the engine to quickly get away from you and overwhelm the valve spring. And its not just a 1 - 1 relationship benefit.....due to the laws of physics the weight savings is squared in its benefits (F = MV squared....the "m" in this equation being the weight of the valve).

There are many reasons I have chosen to always run hollow stem (or titanium) valves all these years and part of the success of the packages I build is achieved by paying attention to all the details....reducing valve weight being one of these important details often overlooked and that's a mistake.

I even pay attention to the weight of the retainers and the actual valve springs themselves.....any savings there is the same as losing that much at the valve.....its all on the same side of the rocker arm that is the most important

-Tony

 

The chassis Dyno data is garbage to me. Different days/conditions, after swapping heads and setting up the valve train again. Plenty of examples of the same car dynoing on the same Dyno and making different numbers. The engine Dyno showed zero gain.

 

Is the .4 second gain that showed at their test track also garbage to you?

It was not evident on the engine dyno as the HP numbers were the same. 421hp The revealing test was on my chassis dyno, when we put the engine back in the car with everything exactly the same the car made 37ft/# better and 21HP and was 0.4 seconds faster at Lanier National Speedway where the car had thousands of laps.

Hard to trust veracity of internet data, I tend to agree but seemed like that particular tester/data collector was in a good position with appropriate research and resources to provide a quality data point.

 

Which is why I said "change in the curve" and not "gain."

 

To your first questions, it's commonly accepted that every gram of weight reduction in the valvetrain adds 35 to 40 rpm potential to the engine, which is based off trends seen in the dyno cells around the world.

And your second, since the valvetrain is a system of parts that have to work together, the spring force requirement is a result of the mass of the system as well as how quickly those parts have to accelerate. How much less spring pressure can't really be answered without knowing the whole system, or just testing by trial and error.

 

I haven't seen the factory LS6/LS3 cams compared to anything on a spintron, but I do know some of the solid roller stuff is super mild. Outside of the LS world we live in, guys have been spinning 3/8" valve big blocks over 8k with a solid roller. Knock 50g off the valvetrain by going to a 8mm hollow stem and now you don't need as much spring, so now you can use 1.3" diameter dual springs that's another 30-50g lighter than the triple springs you were using and it just snowballs from there.

 

It's better than if it were .4 gain in the 1/4 😂

 

Good info on the 35 to 40 rpm gain! I hadn't heard that before.