MTIRC6Z

I started out by saying: "I applaud Katech's willingness to do some spinton testing"...not sure how anyone with an IQ higher than 50 could possibly misconstrue those words to mean any disrespect to Katech or this thread

I did however go on to point out that this testing had nothing to do with 'root cause'...I did this because Ricky had already made numerous references to a previous thread he sh*t on throughout which was attempting to determine a 'root cause'. Personally I knew exactly what Katech's testing was about but feared others were not, given the references to the 'root cause' thread and thus thought it was worth pointing out the difference.

As far as cost and other people's engines, Howie asked me if I thought it was possible for heavy valves to be controlled at or above 7000rpm, I merely said that while it might well be possible it might also be expensive...not sure how anyone from that could conclude I actually CARED what it cost someone else

As for Katech's claim they were merely the messanger for GM's 'the issue is simply the guides' I appreciate the clarification...I was well aware that Katech was confident that merely changing the guides would resolve any issue but I was also under the impression that to be so confident they would know exactly why a simple guide change was all that was needed...my bad. Thing is, passing on a message that has little credibility doesn't help the credibility of the messanger.

As for my "face" I must unfortunately admit that I get absolutely none of it from this or any other forum on the internet, my face is obtained in the real world through personal relationships and not over the internet. I believe the issue at work here is referred to as "projecting"

At this point I believe I should call upon some valuable knowledge I gained from the 'root cause' thread where I was enlightened by the idea of "disengagement"

Cheers, Paul.

JetBlue427

I have read a few articles related to float or bounce...and non of them explain what kinds of damage would occur? can you briefly give us newbies a lesson in what can go horribly wrong if the setup we choose has bad dynamics?

zcarbon

vertC6

Now that's funny,


Anyways back to testing, Jason I would be willing to contribute $50 (as I am sure many others would) to test the yella terra light weight rockers. Hell I bet if you called them and told them what you were doing they would send you a set for free or very cheap. just a thought.

pewter99

ok folks...I reallllllllly don't want to go in and clean this thread up so please police yourself...and lets try and be civil....

if you posted something that you think I think needs cleaned up please do so..

SmokinZ

Thank you!

'06 Quicksilver Z06

I went back and edited a lot of my stuff, particularly where I referred to Paul by name.

I mentioned before that I am elated that Jason and Katech are making this move and doing some meaningful research which shows promise in being of benefit to our membership.

Research into subject matter which has been discussed on this forum for months now, and that is the valve train stability of a common modification done on this forum. I still believe that.

We can tell just how common it is in the number of members here, over 140, who have done it. It helps some of us, who want to know, via spintron testing, if what we are currently running, is stable. So the accusation that we "sleep better at night by not knowing" is unfair.

So in actuality, any consequential research, which might shed more light on even current, or planned, configurations and their stability, should be welcomed.

It is for that reason that I support Katech in their efforts, and Jason in his steadfastness, in going through with this endeavor and look forward to his results.

Many in here, myself included, await the outcome of their testing.

bluemagoo

Jason asked for possible components to test valve train stability. There have been a number of suggestions posted. I'm happy to wait for the results now.

Perhaps the moderator should consider locking this thread until those results are in. I really don't want to have to wade through page after page of off-topic arguments like some other threads (you know the ones). Thank you.

Bad_AX

Jason, one more suggestion for the Epic Spintron Test.

I am interested in knowing what, if any, affect anti-friction coatings on the stock LS rocker have on valve train stability. There was quite a bit of discussion at this link http://www.yellowbullet.com/forum/sh...2&postcount=42 on the Jet Hot coating reducing rocker deflection by about 50% which by association would reduce valve stem deflection. It is stated in that thread, "I believe it will reduce damaging harmonics and help the engine stay at higher hp levels longer". It would be great for a change to be able to say "WE KNOW".

I'm not sure Jet Hot is really intended for friction reduction in moving parts, but Katech may already be using coatings for race engines that could be applied to the LS7 rockers at your facility? I have also considered the CHE Precision Rocker upgrade which replaces the needle cage with a bronze bushing and hardened steel shaft, but real data on these arms is scarce. Would you also consider testing the CHE Precision Rocker. Maybe WCCH would donate some for the cause?

Thanks again for doing this project.

atljar

Its been mentioned a few times already, but I too would like to see data on aftermarket rockers / how the nose weight affects stability of the valve.

Great test, thank you!

'06 Quicksilver Z06

Depending upon when the testing will be done, I sent my spare set of rockers out to WCCH for the CHE upgrade, and have a set of CHE rockers on the way back, and still have my stock rockers in my car.

I have no plans of immediately installing the CHE rockers.

So if Katech is interested in using these for their testing purposes, I would be happy to loan them out to them.

Let me know Jason.

Bad_AX

This is what I hope this thread and test will be about.

Thanks for making a great offer Quicksilver!

30YR W8T

Hats off to Katech for taking on the task of evaluating the different combination to determine what actually tested out to be the best possible approach on a variety of combinations with stable dynamics being the focus. Those results would just add another convenience of having a well tested package that removes all doubt about which components work the best on several fronts when combined.

As some others have mentioned, it would be interesting to see if there are aftermarket rockers that do indeed provide some dynamic stability to the valves by reducing flexing. It would also be interesting to see if a different combination of rocker and springs may achieve better results as well on the stock valve set up. This testing may uncover some unknown issues and deliver some unexpected results as well....

Z.06

Nothing but Kudos to Katech for doing this, and I would expect that Jason had to demonstrate a business case to justify the testing. Thanks Jason!

I am about three months out from a decision point on what to do with my Z06. Yes, that is when my drivetrain warranty expires and I have no GMPP this time around. I did a couple of searches and did not turn up anything WRT the schedule or timeline for the testing. My apoligies in advance if it was covered and I did not see it.

Does anyone have info on the schedule for testing and publication of the results?

KLJ

This is a great plan.

I looked at the earlier article and data and noticed that the working temperature of the components was missing as well as sweep rate through the rpm range.

I understand that sweep rate will be difficult to vary with only a 30hp motor.

Perhaps the data in the earlier article is stabilized or steady-state measured every 200 rpms? [Ten datapoints from 4000 through 6000 rpms, for example.]

I see from the picture of the setup that oil is supplied remotely so it should be straight forward to preheat and regulate the temperature to normal operating conditions.

If you are doing testing of the stock components as your baseline then it is absolutely critical to have the NaK in the exhaust valve stem in a liquid state to have any hope of approaching the correct modeling of its behavior in an operating engine.

Simply matching the weight, or more properly the mass, of a hollow stemmed or solid stemmed valve against a NaK valve at rest and low temperature with solidified (or granulated/powdered) core does not allow for the variable mass/inertia being accelerated or decelerated at any given instant by the valve train system over a wide range of rpms and sweep rates.

Thank you for performing this incredibly valuable service to the Corvette community and sharing the data.

Kind regards,

Kevin

Hib Halverson

Stock LS7 exhaust valve is 68-grams.

Info, dated 8 Jan 2013, comes straight from the person on the valvetrain engineering team at GM Powertrain who lead the LS7 cam/valvetrain development in the early-to-mid-'00s.

mistermog

Ive never seen a <71g weight for a stock valve... huh...

Mark2009

Early production was 71.7g. Later production (EDIVAL 09-08) is 74g. Straight from the scale

Change may or may not have coincided with reported change in part number early (Feb.?) 2008.

track junkie

What would you recommend they do to get the NaK in the exhaust valve to normal operating temperature during this valve stability test?

KLJ

The NaK alloys appear to have more consistent viscosities up around 400 C to 500 C. [A typical jump is to ~.18 at 500 C from ~.50 at 98 C (viscosity in centipoise).]

Without knowing exactly how the laser beam is bounced off the exhaust valve, it might be possible to waterjet a Pyrex plug for the cylinder bore that would still allow the beam to pass through.

A regulated heat gun could be aimed through the intake port (no intake valve used for this test) and the exhaust valve allowed to cycle normally. So that would be two modified block off plates going by the rig picture. The head and possibly block would need coolant passed through at a regulated temperature (normal operating temp) so that heat applied to the head and exposed stem of the valve could be rejected as normal to the guide and seat. The Pyrex plug could be positioned/pinned in the bore to confine flow to roughly the combustion chamber volume, allowing for valve lift extrema.

The varying values given for the exhaust valve weight might suggest some sort of fine tuning of the liquid metal reciprocating cooling mass was being attempted (?). You would have to dissect the valves which is a hazardous process. If multiple iterations of the OEM exhaust valves are available it might be interesting to compare them.

Also, perhaps Katech would consider releasing the raw data stream from the tests to allow people with equipment for analysis to check it using alternate filtering and/or smoothing algorithms.