VetteVinnie

That's not from the article. That's from Katech's empirical data. There have also been several discussions about the oil getting coked to the stems.

http://forums.corvetteforum.com/1578667842-post31.html

But, of course, you weren't around in 2011 when we were discussing this.

"The root cause of the guide wear is engine oil coking due to severe temperature. To fix the problem at the fundamental level, GM needs to go with smaller multi exhaust valves instead of one large one. Horsepower is heat, and there is too much horsepower flowing thru one exhaust valve. That's why GM, as well as Katech, runs pig rich mixture in an attempt to cool the combustion temp."

Vette @ 71

Have the feeling we are not communicating. I am not a fan of temp being responsible for causing guide wear of oem guides, since intakes which see much lower temp's are also showing oem guide wear..

Whence guide wear starts, oil will start to coke on the valves and accelerate guide wear, but not the principle instigator..

propain

This was being discussed before anyone could have possibly imagined GM's head supplier was sending out heads with machining issues and people were grasping at staws trying to figure out why these cars were failing.

However it has since been proven by the inspection of heads and having the intake side being out of spec and the exhaust side being in spec that this theory is wrong. We have also seen LS7 heads with zero miles straight out of the supplier with machining issues that would have lead to premature guide wear.

As well as who knows how many 1000's of Z06's out there with ZERO issues and no guide wear what-so-ever. If this was a heat issue 100% of the Z06's would have measured guide wear. They do not.

Dirty Howie

I understand that there are two separate issues. All I am saying is that your same logic can be applied to the SS valves...........they don't exhibit any affects on the valve train although theoretically (via spintron) they should.

Hopefully we agree on this concept


DH

propain

Not really enough time or a big enough sample to conclude the heavier valve has no long term effects on the valve train.

Dirty Howie

Propain

We really don't know how large the sample size is, only how many CF members have employed this fix.

Certainly the sample size on the new hollow unfilled valve is very small at this point.


DH

Mark2009

To set the record straight (as I often see the misleading claim above repeated), the Ferrea Competition Hollow Stem valve is not "new" -- it has been out for years, available for the Chevys, Chryslers, Fords, and Toyotas. From what I have read on more professional-oriented forums, they enjoy an excellent reputation amongst engine builders.

They are only "new" in the LS7 size. Therefore, like Michelin making a new sized tire for the new C7, I don't think there is anything to 'fear'... their reputation in similar applications precedes them.

vertC6

Ferrea has had these valves for years, just check out their site they have about 50 different sizes and applications.

Mark2009

I would suggest an interview with a Ferrea engineer, or even a GM Powertrain engineer, giving them an opportunity to comment on your valve ranking.

I've sent you one interview candidate via PM.
.

ramairws6

No, I would go with the TI valve. Of course weight is a big issue in this setup but not near enough when we are talking about valves separating and destroying blocks. So when the SS valve has been used for how long by so many people and seems to work good why even take a chance with that cheap *** sodium filled garbage. Simple as that. I spray my motor so titanium was not an option but if it was that would have been the route I took

propain

As you can see from the replies above that beat me to the punch... these valves have been around for a very long time.

propain

HAHAH... as if the SS valves are some type of expensive upgrade...

As well your build does not apply since its super secret and "proprietary".

Hib Halverson

I did get the PM, "Mark2009". I have been doing what you suggest. Since 2001, a regular source, when I've done articles about Gen 3/4 V8s, has been Jim Hicks, the GMPT engineer who designed and developed the valves and the rest of the valvetrain in the LS1,2,3,6,7 and 9.

Dirty Howie

If you don't want to have a discussion with me as you recently requested then don't bring my statements into your posts

Obviously, my reference to new, was as in new for the LS7

Do we want to start discussing how many makes of cars modded or otherwise have been using SS valves for decades.

So please ignore my posts as you have requested me to ignore yours


DH

Dirty Howie

I understand that point. But we are specifically talking about our LS7 which I think you will agree has its own set of peculiarities. I think we might also agree that not every valve is going to behave the same in different motors.

I could make the same argument for the SS valves. They have been around for a lot longer than Ferrea and used in many more applications.


DH

ramairws6

Could care less on the price. $5---$5,000 it doesn't really matter if they bust in half and grenade the motor. I see your the type of guy that would rather pay more for a two-Piece valve and the name if ya know what I mean

Dirty Howie

Hib

I'm not sure everyone knows how long you have been researching this issue. I know from our conversations that you are well connected and not shy about extracting information from your sources. Your mechanical abilities are also not widely known. Possibly stating your credentials might be helpful for some.


DH

'06 Quicksilver Z06

While that may be true, Stainless steel valves have also been "out for years" and available for "the Chevys, Chryslers, Fords" for years.

However we know where the discussion leads when we try and make that argument that they are OK for, and that they thus far are doing well in this LS7 engine.

The argument usually trends along the lines of "they might be OK for other engines, but not this one because the spintron says so", despite the fact that they are doing well in these cars.

It seems to me that if we are going to use that as a legitimate argument "against" the use of SS valves in the LS7, then I don't see how the same argument could not be made against the Ferrea hollow stems.

Ferrea hollow stems may well have been around, and used in other engines previously, but how about in the LS7?

And more importantly, as mentioned before, while the SS valve may not have shown stellar results on the spintron for these cars, that which might be the achilles heel for the Ferrea hollow stem valves in these cars, i.e. the question of adequate heat transfer from valve head to stem, cannot be tested or measured on the spintron.

While it may be Hib's opinion that the Ferrea hollow stem is the "worst" choice of the lot for these cars, he does make a good argument for that, and I am beginning to see his reasoning in making that assessment, we won't really know which of the two, SS valves, or the Ferrea hollow stems, actually end up being more "hazardous" to the LS7's health. But overheated exhaust valves, can and do lead to their failure.

At any rate, knowing what Hib pointed out, and the discussion thus far on it, well, whereas I once thought that changing over to the Ferrea Hollow stems could be done with virtually little to no consequences which would warrant concern, it appears that there are in fact some concerns to be taken into serious consideration, namely heat transfer, which might be just as significant as the weight concerns with the SS valves.

One aftermarket solution, the use of Ferrea hollow stem valves, might wind up being just as "risky", and potentially "deadly" as the other, the use of SS valves, but for different reasons.

It seems that "weight" has always been the concern. But there are other things which could end up being just as big of a concern.

There has to be a reason why GM used sodium in those valves instead of air.

If they were just looking to decrease "weight" in the stock valves, well then why fill them with sodium?????

We won't know though until the Ferrea Hollow stem has been in use in the LS7 for as long as the use of SS valves has been used thus far, and in a comparable number of C6 Z06s, before we can get any kind of assessment.

'06 Quicksilver Z06

Exactly....

But when you do make that argument, what typically happens is a counter argument that while what you say is true, that does not apply to the LS7.



I have also had the pleasure of corresponding with Hib via email and PM on things ranging from the is issue all the way up to motor oil.

It would be good if he were to state his credentials.

'06 Quicksilver Z06

Well CG, to your part in bold, how would we know if they did or not?