QKSLVRZ

It's not the be all, but as nitrojunky pointed out there is currently no other way to actually look at the valve in "pseudo" operation. It's also a much more economical way to stress test a valvetrain to failure. Yes, it is only mechanical stress, not thermal. It would be nice to have both, but it is far cheaper than running 5 or 10 engines to failure on a dyno. And you could probably mount a torch to blow on the exhaust valve if you wanted.

Most of your real world experience isn't statistically significant. Not a lot of samples, nowhere near enough operational time, inconsistent setups, and no test plan.

Lastly, there's most likely nothing wrong with many of the SS valved heads that a possible lower rev limit wouldn't cure, but you don't know.

And I am annoyed that Katech decided to stop sharing what they were seeing on their spintron, they were showing us the results of thousands of dollars in testing that I will never get a chance to see now. Everyone gets you had unanswered questions, its just I wish you could have gone about getting answers a different way.

'06 Quicksilver Z06

I read with great interest one of your last post, where you mention warranties and such, and I believe that you even bring up the LS6.

Also on a side note, with regard to Katech's representative and that thread, I really don't understand the rationale behind blaming me. The whole notion of I'm going to take my ball and go home, and "punish" the rest of y'all, I don't get.

I'm going to withhold information, because I don't like the questions asked????

I don't understand that.

That isn't my fault.

I believe that there have been 26,065 C6 Z06s built.

They built 6,272 2006 Z06s. Did you know that for MY 2006, the power train warranty was only 3/36,000 miles and not 5/100,000 miles?

So if I'm right on that 26,065 number, then about 24% of all Z06s built, did not have a 5yr/100K mile power train warranty on them.

Also, I have no idea as to GM's warranty exposure in this matter. But I do know that they sell a lot of Cobalts, and other vehicles, which likely offset some of whatever liability they would have on the Z06. It should also be considered that a portion of warranty cost is figured into each vehicle they sell.

Also, marketing it as a track capable car, and then not honoring warranty claims were it to suffer failure under the conditions it was marketed for, would of course limit their exposure as well.

So your points about 5/100,000 mile warranties, have to be taken in the context of each of the above.

Furthermore, by the time that announcement on the 2008-2011 models and guide mis machining was made in September of 2012, many, if not most of the Z06s built, would have been out of factory warranty.

Or better put, anything put into service 60 months or more prior to the release of that statement.

Knowing that the first 2008s came out in late 2007, has to be considered as well.

As for the LS6 in the C5 Z06 and it's use of hollow stemmed sodium valves, well, what I would do, is ask a cylinder head professional about the length of the two valves, the fact that the LS7 makes 100 more horses than the LS6, runs at 500RPM higher red line, and about any variations in generated heat between the two engines.

I'd ask if any of these might make a difference when attempting to compare the use of this type valve in each of these respective engines.

You might even have other questions with regard to the differing circumstances between the LS6 and the LS7 and what if any role that plays in what we are seeing.

He might tell you about the mis machining issue, but when/if he does, ask him how that explains the valve drop issue in the 2006 and 2007 models.

They made 8,159 Z06s for 2007

That's a total of 14,431 cars, or better than 50% of production.

Ask him why this matter has shown up in them too, when GM says that it affected 2008-2011 cars.

Are you taking into account the fact that people have been building engines and they have been running fine, without the testing you mention?

All of these cylinder head companies out here, continuing to make good on these setups and others............How do you think they made it? Blind luck????

You seem to have a lot of confidence in General Motors.

I'm not knocking that, as they make great products. But I don't trust much of what they have to say about this matter.

QKSLVRZ

Did the valves and springs come as a kit? Was there any documentation on weight and rpm?

zcarbon

Sorry, Can't do nothing about my head But, the suit is sharp
Horse Hockey C'mon, Why not stick with GM or Katech on a build?
Why use" Shadys fix shop" ydns

'06 Quicksilver Z06

Yes, you're right, it's not propaganda.

I encourage people to talk to the company which begins with a "K" and see what they have to say about this matter.

As well as talk to professionals out there whose opinions and experiences differ from theirs and their test findings.

And then make the best decision which suits them.

'06 Quicksilver Z06

I'm sorry buddy, And for a long time, I've gotten a chuckle out of reading your posts, and I really mean no offense here, ......but I just can't get past the image of a hog headed executive making comments on this matter.

It's almost like every time you say something, ....it's like "he's" talking to us.

So when a hog starts talking about "horse hockey" I just about $#** my pants.

I guess it's this way because for so long, people posted up images of themselves as avatars, and I'm having a time making the disconnect. But every time I read something that you write, and I look over at that hog, I just bust out laughing.

adamgl

My car had a port / polish / machine / and valve job done back in 2009 by WCCH (before I owned it). They used Solid stainless valves and reused stock guides.
I checked them last year and they were loose. Had them put in new bronze guides and springs.
Maybe the guides where on the brink of being bad the whole time on my car?

zcarbon

That's OK, I'm goin'on a diet
But my question, Why pass up GM or Katech and trust Shady

QKSLVRZ

I take it in the context that they offer it at all.

So what, while local experience may differ, GM seems reasonably willing to replace engines when they drop valves under warranty. It's more a matter of their having done enough lifecycle testing to think there's enough of a chance it will not need a $17,000 free engine replacement to sell it in the first place. And there are things I don't like about GM, but I like my corvette, and I can't afford the same level of performance from a brand that has a life time warranty, actually does anyone have a better manufacturers warranty for equal or better performance?

LS6's had similarly constructed valves, point that they can be reliable. I would have considered that they took what they learned by running the LS6 program, plus a number of years working on the LS2, LS3, LS7, LSA, and LS9 sorting out the valve trains (and yes I know they are not all the same).

Combustion temps should be similar, the rpm, cam, geometry changes would all need to be accounted for in lifecycle testing. It's possible that a few % failed before 100,000 miles and they said to ship them anyways, it's possible they all passed.

All of the reading on hollow stem valves does say they don't tolerate guide/seat misalignment, and fail by popping off the valve head. GM, if the identified the exact cause, kept it to themselves, it's a shame, but the lawyers are always circling.

Well, in the early years it was blind luck, then that became rule's of thumb, lately probably a lot more simulations are getting run in a box of rule's of thumbs, with a dash of luck thrown in.
The further you are from the guys who have the budget and equipment, the further you are from what's really going on, most places don't share the results of testing with customers.
Manufacturers run these kinds of tests, create guide lines on the application of components. Vendors get to consult with most manufacturers, "these springs work for this kind of weight, to about such and such rpm" or they put a kit together and say you can run this to 7200, and the tuner should set the limit to what they feel is prudent. Katech mentioned they set the limiter to a higher value for street use, than a road race engine program would recommend.

When you're planning on selecting a head and cam package, what's your criteria for a successful life span, and what evidence do you accept for proof of that success?

ctsv510

Not a kit, they are what the shop I used stocks and uses. If you're asking about a spintron test, yes Katech tested the combo and called it safe for a street car.

QKSLVRZ

I was trying to figure out how far back you had to go to find someone who tested at least something like it.

Did they give you a rev limit, or just imply you could keep the stock limit?

Mark2009

Install an EGT gauge in cyl #7. Offhand I'd suppose that you'd want to stay under 1500F, and my counter-intuitive theory is that moderate-heavy load at low RPM may be as or more problematic than WOT.

Mark2009

Perhaps it's just a lack of paranoia



Ferrea drilled valves? Unproven, run away!

Ti valves? Guru says unproven, run away!

Sodium valves? Satan's spawn, run away!!!!!!!

Spintron? Snake oil hocus pocus, run away!

Vendor-generated lab tests? Marketing lies, run away!

Engineers? Elitists, run away!

Science, physics? Lies, damn lies, run away! Trust no one with an IQ over 30!

'06 Quicksilver Z06

I'm not as impressed by that as you seem to be. Whether or not they offer the warranty of 5yrs/100K miles, depends to large extent on what they believe their exposure to warranty claims to be. And that can be impacted by a lot more than quality or durability, as you seem to imply.

When I was looking into extended warranties with my prior Corvettes, one of the big warranty vendors in here told me very aptly, "you're buying time, not miles."

He was right.

And that brings me to your prior comments and carries me to answering the final comments in your current post. If I offer you a warranty which is going to run out in 60 months, I can offer you more than 100,000 miles if I know that you will never come close to that.

Time would be on my side, because when 60 months is reached, I am no longer at risk to have to make good on my agreement with you. Many of these cars are sold in the north and northeast, where they are only driven 6 months out of the year. Many are also 2nd, 3rd, 4th or 5th vehicles.

GM, has an idea of how many miles the typical owner, or even the majority of owners, of one of these cars is going to drive it over that 60 month period.

And they know that it is not going to be anywhere near 100,000 miles.

So when they offer 100,000 miles, they expect just the response you see. People say, "well, oh, if they are warrantying it for 100K miles, well then it must be tough as nails".

No. Because they know that at the end of that 60 months, out of 10 owners, very few of them will be anywhere close to 100K miles. So for the average owner, they're warranting it for "60 months".

Or 30-35 months, if that owner is in some of the colder climates where the car is only going to be driven 6 months out of the year.

Cars which have been sitting up over the winter months, are at more risk for electronic issues.

Notice how the warranty on those type things is for but 36 months.

So I don't look at a 5yr/100,000 mile power train warranty in this case as any indicator of durability, so much as I look at it as evidence that GM has carefully looked at all factors which could make them liable to a warranty claim, of which durability is just one.

They are more concerned about "time" than they are miles. And the clock is running from the day that the vehicle goes into service.

On a side note, the average person who can afford one of these cars, very likely has other interests and hobbies.


Well not to argue with you about comparable vehicles, but I return again to the warranty.

That warranty is based upon GM's analysis as to their risk.

That can be impacted by a number of things aside from stoutness and durability.

We already talked about on track incidents, propensity towards storage in parts of the country, and average owner's use during the time while the warranty is in effect.

Well, yes they are.

And it's part of the reason why I don't believe that GM is going to tell us all that there is to know about this matter.

It's just hard to argue with the success of so many others going about this in a way contrary to what one vendor says.

With regard to your last paragraph, it goes back to that which I talked about earlier, with regard to "time", but it also goes to how I plan to use the car during that "time".

I don't expect to get 100,000 miles out of a cammed car.

I have other vehicles to drive, and do not drive this car to work.

My car currently sits today at

It was purchased in August of 2007. So you can see, I really don't put very many miles on it. So, what's that, about 3,200-3,500 per year or so. In Westerrn Pennsylvania, where the winters are long, and the snow and ice can wreck havoc on the roads, that's about all I'm going to get to drive it.

Of that some of the miles have been occasional trips to the drag strip, it might see a drag strip rental or two over the year, and a test and tune or two, or to the local road course for HPDEs. But trailering it and taking it to the track, is hardly a weekly thing for me either, even though I own a trailer.

But that said, I expect it to last during the period of my ownership, the way I use it, regardless of miles. And I expect it to hold up during those times when I do track it.

When it was stock, I had no confidence in it doing that.

Plans: Really, I don't know just yet. I don't see myself getting rid of it, and I don't really like the new ones. And considering my other hobbies, guns, golf, sports, well, like the rest of my "toys", I want it to be reliable when I go to use it.

nitrojunky

except for the valvetrain mods, i'm bone stock. didn't even port the heads because i wanted to stay pretty much stock from the engine perspective, but if i track the car, i'll probably do the EGT sensor to be comfortable. hell, i may do it anyway just to satisfy my curiosity though the pig rich stock tune should should be Ti friendly.

QKSLVRZ

So, then your definition of success is your car lasting until you get rid of it?

With success defined, what proof do you have to say it's met that standard?

'06 Quicksilver Z06

Basically.

Why would I need for it to last any longer than that?

If it's still running when I get rid of it, then who can argue?

FSTFRC

^^^ Quotes from a 'pseudo engineer'

'06 Quicksilver Z06

Out of curiosity, how do you define it?

I can tell you this though, when the work was done on my car, there was some galling and coking of the exhaust valves, and a couple of the guides were out of spec. So even with the low mileage that was on it when the work was done on it, I'm convinced that what I did, may well have saved, and probably did save my engine.

That 23,666 that you see, I don't think it makes it that far had I done nothing.

And the reason why I don't think so, is because there are other cars in here which have failed before reaching even that point, and currently knowing the condition of my heads and valves which were removed.

BTW, and out of curiosity, I see that you are right up the road from me in Ohio. How many miles do you have now and how many do you put on it per year?

nitrojunky

if looking at it with failure statistics, a statistically significant difference between the failure rate at a given mileage for the fixed heads vs. the failure rate at a given mileage for GM produced heads during the build dates where there is an issue (which as far as i'm concerned is 2006-present?). this is for stock. stock cam, stock tune. also, desirable to control for track days. statistically significant can have several defns. it could also mean moving the failure rate curve up some significant number of miles. all while no measurable decrease in performance. for guys with cams, the measurement would need to be different. we haven't yet made it there with statistics, but keep collecting and we may be there in a couple or few years. << not being sarcastic; i think it'll be a few years for the failure method of measuring, and that assumes this thread continues to gather data.