[Z06] What would YOU do to make your LS7 heads bulletproof?
09-03-2011, 04:28 PM
#121
Only a small percentage are tracked, only a small percentage are modded, and only a small percentage have problems.
Plenty of non-traced failures? Okay, maybe I"m getting a little testy on this subject - how many? Sure, I read the forum several times a day as you know. I'm guessing we can find maybe....MAYBE five non-tracked, non-modded failures.
And yes, I'm goading people to prove me wrong.
Plenty of non-traced failures? Okay, maybe I"m getting a little testy on this subject - how many? Sure, I read the forum several times a day as you know. I'm guessing we can find maybe....MAYBE five non-tracked, non-modded failures.
And yes, I'm goading people to prove me wrong.
Of the five non tracked cars you mention, none of them were silver. So I should be OK. Ah yes. How many bone stock failures? How many bone stock/non track failures?
What number of each would be considered "unacceptable"?
Or in other words, how many of each would you have to witness or hear about before you believed that it was a problem?
Everybody is going to answer that differently.
If it fails, bone stock on the track, seeing as how it is marketed in part as being track capable, is the fact that it failed on the track a legitimate "excuse" for it having failed? Does it get a pass because it failed on a track instead of on the street?
The fact is, everyone in here is going to reach a threshold where they feel that the the repeated descriptions of these failures, and issues which seem to usher in failures, or set the stage for failure, worn valve guides, bad rockers, broken valve springs, low oil pressure, be they stock, modified, tracked, street, is excessive.
Brake issues, yes, but I can find but one description of one losing an engine in here. Modded, stock, red, white, blue, whatever, I can only find one.
However I can find you at least a few "representatives" from the stock LS7 group, modded LS7 group, stock and tracked LS7 group, modded and tracked LS7 group, drag strip LS7 group, road course LS7 group, stock and street driven only LS7 group, red group, blue group, every group.
Give me most any group from within the LS7 camp that you want to see an example of an engine failure occurring in, and I'll find you at least one representative from that group.
09-03-2011, 04:51 PM
#122
Team Owner
You can break them down by color too. Of the five non tracked cars you mention, none of them were silver. So I should be OK.
Ah yes. How many bone stock failures? How many bone stock/non track failures?
What number of each would be considered "unacceptable"?
Or in other words, how many of each would you have to witness or hear about before you believed that it was a problem?
Everybody is going to answer that differently.
If it fails, bone stock on the track, seeing as how it is marketed in part as being track capable, is the fact that it failed on the track a legitimate "excuse" for it having failed? Does it get a pass because it failed on a track instead of on the street?
The fact is, everyone in here is going to reach a threshold where they feel that the the repeated descriptions of these failures, and issues which seem to usher in failures, or set the stage for failure, worn valve guides, bad rockers, broken valve springs, low oil pressure, be they stock, modified, tracked, street, is excessive.
Well there are only about 3,798 2009-2011 ZR1s out there. But I mention this before, you have heard barely a peep out of them when it has come to engine issues in that car.
Brake issues, yes, but I can find but one description of one losing an engine in here. Modded, stock, red, white, blue, whatever, I can only find one.
However I can find you at least a few "representatives" from the stock LS7 group, modded LS7 group, stock and tracked LS7 group, modded and tracked LS7 group, drag strip LS7 group, road course LS7 group, stock and street driven only LS7 group, red group, blue group, every group.
Give me most any group from within the LS7 camp that you want to see an example of an engine failure occurring in, and I'll find you at least one representative from that group.
Of the five non tracked cars you mention, none of them were silver. So I should be OK. Ah yes. How many bone stock failures? How many bone stock/non track failures?
What number of each would be considered "unacceptable"?
Or in other words, how many of each would you have to witness or hear about before you believed that it was a problem?
Everybody is going to answer that differently.
If it fails, bone stock on the track, seeing as how it is marketed in part as being track capable, is the fact that it failed on the track a legitimate "excuse" for it having failed? Does it get a pass because it failed on a track instead of on the street?
The fact is, everyone in here is going to reach a threshold where they feel that the the repeated descriptions of these failures, and issues which seem to usher in failures, or set the stage for failure, worn valve guides, bad rockers, broken valve springs, low oil pressure, be they stock, modified, tracked, street, is excessive.
Well there are only about 3,798 2009-2011 ZR1s out there. But I mention this before, you have heard barely a peep out of them when it has come to engine issues in that car.
Brake issues, yes, but I can find but one description of one losing an engine in here. Modded, stock, red, white, blue, whatever, I can only find one.
However I can find you at least a few "representatives" from the stock LS7 group, modded LS7 group, stock and tracked LS7 group, modded and tracked LS7 group, drag strip LS7 group, road course LS7 group, stock and street driven only LS7 group, red group, blue group, every group.
Give me most any group from within the LS7 camp that you want to see an example of an engine failure occurring in, and I'll find you at least one representative from that group.
You say you can give me a few from each group - have at it. I want to see a few. In God we trust, all others bring data!!!
09-03-2011, 05:22 PM
#123
Safety Car
Only a small percentage are tracked, only a small percentage are modded, and only a small percentage have problems.
Plenty of non-traced failures? Okay, maybe I"m getting a little testy on this subject - how many? Sure, I read the forum several times a day as you know. I'm guessing we can find maybe....MAYBE five non-tracked, non-modded failures.
And yes, I'm goading people to prove me wrong.
Plenty of non-traced failures? Okay, maybe I"m getting a little testy on this subject - how many? Sure, I read the forum several times a day as you know. I'm guessing we can find maybe....MAYBE five non-tracked, non-modded failures.
And yes, I'm goading people to prove me wrong.
Let us know what you find.Back when the rocker arm failures were the hot news (was that before or after the piston failures, or was that the cylinder liner failures?) I believe someone did compile a list. It got fairly long.
09-03-2011, 05:43 PM
#124
Melting Slicks
I track my car (road course). It currently has stock LS7 heads - in fact I bought them used from a friend with 12,000 miles or so on them, and he drag raced the car a lot. I have a HUGE cam (just ask Jason). Katech checked the condition of the heads when they built my engine and to my knowledge they did not replace any valves or guides.
Because I track the car I plan on doing the appropriate maintenance that a track car needs - which means not expecting to track it AND get 100,000 miles on it AND never do any maintenance. When it is time I will have Katech remove the heads and do whatever they recommend.
Because I track the car I plan on doing the appropriate maintenance that a track car needs - which means not expecting to track it AND get 100,000 miles on it AND never do any maintenance. When it is time I will have Katech remove the heads and do whatever they recommend.
09-03-2011, 05:51 PM
#125
Team Owner
I'm already convinced, you're the one that needs convincing. As is so often said on CF, use the search! Let us know what you find.
Back when the rocker arm failures were the hot news (was that before or after the piston failures, or was that the cylinder liner failures?) I believe someone did compile a list. It got fairly long.
Let us know what you find.Back when the rocker arm failures were the hot news (was that before or after the piston failures, or was that the cylinder liner failures?) I believe someone did compile a list. It got fairly long.
If you think I need convincing that it is a bigger problem than I think, then someone else needs to bring the data - like the people who are making this into a thread about the Z06 losing resale value and becoming an albatross due to the severity of the problem.
In fact, right now the Z06 has among the best resale value of any car made in any significant numbers. My three year old car is now worth (at trade in, not retail) about 65% of it's original sticker price. I know that because I have checked the numbers recently on the internet and with my dealer. 65% at three years old is better than outstanding, it's almost unheard of.
09-03-2011, 07:15 PM
#126
R - we can debate this all we want, but until someone gives me a better idea of how many we are talking about, then this is becoming less and less meaningful to me. There is zero quantifiable data on this thread.
You say you can give me a few from each group - have at it. I want to see a few. In God we trust, all others bring data!!!
You say you can give me a few from each group - have at it. I want to see a few. In God we trust, all others bring data!!!
People have said that there was something going on here.
There is a chance that they may have been at least part way right.
I said over in another thread in reference to a thread I myself started counting the bone stock LS7 failures described in here up until 2009...
At the time of that posting (in 2009) there had been 25,623 C6 Z06s built to date. At the end of 2011MY, we only have 27,045 Z06s built, only another 1,422 cars. But since the time of that post back in 2009, we are still seeing stock and very near stock reports of failures in here. So why are they still continuing?
...
...
Last edited by '06 Quicksilver Z06; 09-03-2011 at 07:22 PM.
09-03-2011, 07:29 PM
#127
Burning Brakes
Thread Starter
Man, both these threads are on fire! I find myself bouncing back and forth and can't remember which one I am reading sometimes. 
All I know is, I have learned an awful lot over the last few days and I appreciate everyone's frank input.
I wonder if this particular thread would have received as much attention if, the other thread had not been started, and I said something like this in the orginal post;
"If your warranty has expired, and given the history of failed LS7 exhaust valves (however small or large the number may be), what could be done to make your LS7's valve train equally as efficient but less prone to failure".
All I know is, I have learned an awful lot over the last few days and I appreciate everyone's frank input.I wonder if this particular thread would have received as much attention if, the other thread had not been started, and I said something like this in the orginal post;
"If your warranty has expired, and given the history of failed LS7 exhaust valves (however small or large the number may be), what could be done to make your LS7's valve train equally as efficient but less prone to failure".
09-03-2011, 08:06 PM
#128
Man, both these threads are on fire! I find myself bouncing back and forth and can't remember which one I am reading sometimes. All I know is, I have learned an awful lot over the last few days and I appreciate everyone's frank input.
I wonder if this particular thread would have received as much attention if, the other thread had not been started, and I said something like this in the orginal post;
"If your warranty has expired, and given the history of failed LS7 exhaust valves (however small or large the number may be), what could be done to make your LS7's valve train equally as efficient but less prone to failure".
All I know is, I have learned an awful lot over the last few days and I appreciate everyone's frank input.I wonder if this particular thread would have received as much attention if, the other thread had not been started, and I said something like this in the orginal post;
"If your warranty has expired, and given the history of failed LS7 exhaust valves (however small or large the number may be), what could be done to make your LS7's valve train equally as efficient but less prone to failure".
I wasn't going to start one, but Jim is a friend of mine.
Here is a brief one I just compiled since my last post.
He can check the information on these as he wishes.
These are claimed bone stock failures in here SINCE my original compilation in July of 2009, so we are talking about additional reports of bone stock failures in about a 25 month period.
So far, I count 8 claims of bone stock failure since my original post of 7/09. If I recall, there were 10 back then. So add these 8 and you come up with 18 claimed stock failures and counting, on this forum from actual forum members.
No other single C6 model in here can come close to that number of reports of stock failures, over the same period of time.
Z0sictanner
Fast Blue LS6
ratt_finkel
Snaps Z06
rikhek
Upsetatchevy
capitalpiggy
BLKLS7
to verify that it was stock when it broke http://forums.corvetteforum.com/c6-z...yno-sheet.html
8 reports in here, of stock failures in about 25 months is too many IMO. Especially when earlier, it took nearly 4 years, intro of the Z06 2005, until 7/2009, for the membership to put up 10 reports of the same thing.
Last edited by '06 Quicksilver Z06; 09-04-2011 at 09:26 AM.
09-03-2011, 10:24 PM
#129
Team Owner
Jim asked for a list of bone stock failures, I believe.
I wasn't going to start one, but Jim is a friend of mine.
Here is a brief one I just compiled since my last post.
He can check the information on these as he wishes.
These are claimed bone stock failures in here SINCE my original compilation in July of 2009, so we are talking about additional reports of bone stock failures in about a 25 month period.
So far, I count 8 claims of bone stock failure since my original post of 7/09. If I recall, there were 10 back then. So add these 8 and you come up with 18 claimed stock failures and counting, on this forum from actual forum members.
No other single C6 model in here can come close to that number of reports of stock failures, over the same period of time.
Z0sictanner
Fast Blue LS6
ratt_finkel
Snaps Z06
rikhek
Upsetatchevy
capitalpiggy
BLKLS7
to verify that it was stock when it broke http://forums.corvetteforum.com/c6-z...yno-sheet.html
8 reports in here, of stock failures in about 25 months is too many IMO. Especially when earlier, it took nearly 4 years intro of the Z06 2005 until 7/2009, for the membership to put up 10 reports of the same thing.
I wasn't going to start one, but Jim is a friend of mine.
Here is a brief one I just compiled since my last post.
He can check the information on these as he wishes.
These are claimed bone stock failures in here SINCE my original compilation in July of 2009, so we are talking about additional reports of bone stock failures in about a 25 month period.
So far, I count 8 claims of bone stock failure since my original post of 7/09. If I recall, there were 10 back then. So add these 8 and you come up with 18 claimed stock failures and counting, on this forum from actual forum members.
No other single C6 model in here can come close to that number of reports of stock failures, over the same period of time.
Z0sictanner
Fast Blue LS6
ratt_finkel
Snaps Z06
rikhek
Upsetatchevy
capitalpiggy
BLKLS7
to verify that it was stock when it broke http://forums.corvetteforum.com/c6-z...yno-sheet.html
8 reports in here, of stock failures in about 25 months is too many IMO. Especially when earlier, it took nearly 4 years intro of the Z06 2005 until 7/2009, for the membership to put up 10 reports of the same thing.
But the one thing I do agree with is that we are friends, and I appreciate that. Most people don't know that you and I have met and had dinner together, so I'll say to anyone on this thread - "Quick" is a very smart guy who does a lot of homework and is an asset to this forum.
09-03-2011, 10:26 PM
#130
I'm wanting to wind down out of these threads as I think we have all had about as much say as we can at this point. I don't know if I'm right in not worrying or not. Everyone can decide for themselves if the information provided here is meaningful to them or not.
But the one thing I do agree with is that we are friends, and I appreciate that. Most people don't know that you and I have met and had dinner together, so I'll say to anyone on this thread - "Quick" is a very smart guy who does a lot of homework and is an asset to this forum.
But the one thing I do agree with is that we are friends, and I appreciate that. Most people don't know that you and I have met and had dinner together, so I'll say to anyone on this thread - "Quick" is a very smart guy who does a lot of homework and is an asset to this forum.
09-03-2011, 10:58 PM
#131
Le Mans Master
Jim asked for a list of bone stock failures, I believe.
I wasn't going to start one, but Jim is a friend of mine.
Here is a brief one I just compiled since my last post.
He can check the information on these as he wishes.
These are claimed bone stock failures in here SINCE my original compilation in July of 2009, so we are talking about additional reports of bone stock failures in about a 25 month period.
So far, I count 8 claims of bone stock failure since my original post of 7/09. If I recall, there were 10 back then. So add these 8 and you come up with 18 claimed stock failures and counting, on this forum from actual forum members.
No other single C6 model in here can come close to that number of reports of stock failures, over the same period of time.
Z0sictanner
Fast Blue LS6
ratt_finkel
Snaps Z06
rikhek
Upsetatchevy
capitalpiggy
BLKLS7
to verify that it was stock when it broke http://forums.corvetteforum.com/c6-z...yno-sheet.html
8 reports in here, of stock failures in about 25 months is too many IMO. Especially when earlier, it took nearly 4 years intro of the Z06 2005 until 7/2009, for the membership to put up 10 reports of the same thing.
I wasn't going to start one, but Jim is a friend of mine.
Here is a brief one I just compiled since my last post.
He can check the information on these as he wishes.
These are claimed bone stock failures in here SINCE my original compilation in July of 2009, so we are talking about additional reports of bone stock failures in about a 25 month period.
So far, I count 8 claims of bone stock failure since my original post of 7/09. If I recall, there were 10 back then. So add these 8 and you come up with 18 claimed stock failures and counting, on this forum from actual forum members.
No other single C6 model in here can come close to that number of reports of stock failures, over the same period of time.
Z0sictanner
Fast Blue LS6
ratt_finkel
Snaps Z06
rikhek
Upsetatchevy
capitalpiggy
BLKLS7
to verify that it was stock when it broke http://forums.corvetteforum.com/c6-z...yno-sheet.html
8 reports in here, of stock failures in about 25 months is too many IMO. Especially when earlier, it took nearly 4 years intro of the Z06 2005 until 7/2009, for the membership to put up 10 reports of the same thing.
2. fastblueLS6....06'....20k miles....valve failure
3. ratt_finkel.....08'....31k miles....valve failure
4. snapsZ06.....08'.....BEARING FAILURE
5. rikhek.......08'.....33k miles (1432 miles on track)....valve failure
6. upsetatchevy....06'....BEARING FAILURE
7. capitalpiggy.....06'....15k miles....valve failure
8. BLKLS7..........07'.....13k miles....valve failure
9. DoctorV......08'......12k miles.....BROKEN VALVE SPRING
10. tjwong.......06-07.....? mi..........BROKEN VALVE SPRING CUSTOMER CAR
11. KennyC6......?........17k mi......valve failure
12. Larry T.......06'.......? mi.........BEARING FAILURE
13. Darius.......07'.......36k mi.....valve failure....Track use
14. 1stZ.........06'........17k mi...valve failure...TUNED/INTAKE
1stZ......................Rebuilt FORGED ENGINE...valve failure using SOLID SS EXH. VALVES.
Last edited by AirBusPilot; 09-04-2011 at 11:38 AM.
09-03-2011, 11:04 PM
#132
I'm wanting to wind down out of these threads as I think we have all had about as much say as we can at this point. I don't know if I'm right in not worrying or not. Everyone can decide for themselves if the information provided here is meaningful to them or not.
But the one thing I do agree with is that we are friends, and I appreciate that. Most people don't know that you and I have met and had dinner together, so I'll say to anyone on this thread - "Quick" is a very smart guy who does a lot of homework and is an asset to this forum.
But the one thing I do agree with is that we are friends, and I appreciate that. Most people don't know that you and I have met and had dinner together, so I'll say to anyone on this thread - "Quick" is a very smart guy who does a lot of homework and is an asset to this forum.
09-03-2011, 11:06 PM
#133
z0sicktanner....06'....26k miles....valve failure
fastblueLS6....06'....20k miles....valve failure
ratt_finkel.....08'....31k miles....valve failure
snapsZ06.....08'.....BEARING FAILURE
rikhek.......08'.....33k miles (1432 miles on track)....valve failure
upsetatchevy....06'....BEARING FAILURE
capitalpiggy.....06'....15k miles....valve failure
BLKLS7..........07'.....13k miles....valve failure
fastblueLS6....06'....20k miles....valve failure
ratt_finkel.....08'....31k miles....valve failure
snapsZ06.....08'.....BEARING FAILURE
rikhek.......08'.....33k miles (1432 miles on track)....valve failure
upsetatchevy....06'....BEARING FAILURE
capitalpiggy.....06'....15k miles....valve failure
BLKLS7..........07'.....13k miles....valve failure
That's too many valves for me to call it coincidence. I can see why you are taking steps with that motor oil to protect yours.
Last edited by '06 Quicksilver Z06; 09-03-2011 at 11:08 PM.
09-03-2011, 11:18 PM
#134
I agree. I enjoy the debates over the forum and differences of opinions that 06 quicksilver and I share. What people don't understand is the difference between debating and arguing. I will never gang up or personally insult quicksilver as others here have. If you have to resort to that to win an argument, then IMO you have lost. Of course debating a point over the Internet is about as productive as plowing your virtual farm in farmville, but it's still fun. I enjoy these threads and the insight (however small) they bring. Anyways, when I comment I try and contribute something new and helpful to the discussion, so here's some info. I won't say who, but I know for sure one of the names in quicksilvers list was not a stock failure but a badly modded and tuned car on the brink of failure...so that's one less.
OK, call it 7. Still in my opinion, too many.
09-03-2011, 11:26 PM
#136
I agree, too many. I can't help but feel as though this is a puzzle that GM knows the answer to and it's up to everyone else to figure it out. It's still somewhat reassuring that even with all the data GM sees, they still build this engine the same way they did 7 years ago. If they made any changes internally, it would be known and documented and we would most likely be able to deduce why. But nothing. Can we check the supplier history? Did they switch suppliers of the heads or any other parts? That might be a good place to start looking to help prove or disprove the supplier theory.
09-03-2011, 11:29 PM
#137
Le Mans Master
09-03-2011, 11:43 PM
#138
09-04-2011, 12:01 AM
#139
7 and 8
7. DoctorV I'm calling this one a failure. I certainly wouldn't want it after a valve obviously struck one of the pistons, and they just simply replaced the cylinder head and tried to send him on his way.
8. tjwong
The fact that with just a little digging, I can find these, says a lot.
Two more for the road. Takes it to 10.
9. kennyC6
10. Larry T (I missed him when I originally counted up 10 back in July 2009. There should have been 11 back then.)
Too many. I'm counting a total of 20. The 10 I originally found when I wrote that thread back in 2009, and now 10 more. All of them supposedly bone stock.
One more:
11. Darius
7. DoctorV I'm calling this one a failure. I certainly wouldn't want it after a valve obviously struck one of the pistons, and they just simply replaced the cylinder head and tried to send him on his way.
8. tjwong
The fact that with just a little digging, I can find these, says a lot.
Two more for the road. Takes it to 10.
9. kennyC6
10. Larry T (I missed him when I originally counted up 10 back in July 2009. There should have been 11 back then.)
Too many. I'm counting a total of 20. The 10 I originally found when I wrote that thread back in 2009, and now 10 more. All of them supposedly bone stock.
One more:
11. Darius
Last edited by '06 Quicksilver Z06; 09-04-2011 at 03:26 AM.
09-04-2011, 01:06 AM
#140
Team Owner
Member Since: Apr 2001
Location: Elmhurst, IL (West Suburb of Chicago) & Home of MEGA Horsepower
Posts: 26,715
Received 586 Likes
on
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St. Jude Donor '06
Well! - I must have some pair of lungs if you can hear the sound of me playing your National Anthem, coming from where I live!
I am however, very pleased to play it, that's for sure - because its due respect where respect is due!
Most Automobile Manufacturers only attempt to produce engines for their own product range - and they would struggle commercially and technically to do otherwise .
The LS7 design team does, I think, deserve great credit, because they have managed to produce a product which has a very worthwhile foot in two camps - it has the potential to create revenue for GM from two separate streams of the business. It is used to power unit in GM’s own product line, and it has great sales potential in the Aftermarket business sector as well.
Here in the UK there are, sadly, very few C6 Z06 Corvettes on the road - probably 25 in total.
There are however, a lot more than 25 cars on the road here that are using the LS7 as a power unit!!
Monaro, TVR, Ultima, Gardner Douglas et al. - sharp eyed observers even claim to have noticed an LS7 under the hood of a pre-production test mule of a very exotic, recently released machine, produced by a certain UK based, high profile manufacturer, with very strong links to F1!
Thus, the LS7 design not only provides jobs and income for GM ‘s own employees. But in the broader marketplace it has talent enough in its configuration, to inspire others to create business, generate wealth, jobs and thus put food on the table for families.
Its success in the aftermarket is made possible because of its two major talents - it is able to be offered for sale at a price which makes it an attractive proposition to the aftermarket enthusiast and business owner alike, and its power/weight ratio makes it a technically an eminently suitable choice for those specialist applications which make the aftermarket what it is.
When you don’t have to worry greatly about costs, it is relatively easy to produce a power unit which is flashy and technically complex .
With the ‘cost monkey’ on your shoulder, things get a whole lot more difficult - ‘less is more’ so the mantra goes!
More power, for sure, but less weight and less in the budget to achieve that aim - that’s the regime that sorts the men from the boys, so to speak.
To design and produce an engine such as the LS7 and make it a commercial success into the bargain, is engineering at its best, and requires flair skill and discipline - to my mind the team who designed the LS7 possessed those characteristics by the bucket load, and therefore I pay respect to them .
Not too many enthusiasts motors out there, running M5 crate engines !
No wonder - too expensive, too complex, too heavy and a bit down on power into the bargain - far better off with an LS7!
Regarding the problems some members are reporting with valve train failures, it is really difficult for me to make an informed comment because I personally have not had any problems to date with the valve gear in my LS7.
Also, I don’t have personal access to the equipment and the data necessary to enable me to test the valve train design, and give an informed and accurate assessment of its performance.
Nothing on the face of this Earth is perfect, that’s for sure, so there may well be design flaws - I don‘t know.
You could play the devil’s advocate and say that it would be abnormal not to find some wear on the valve guides, after a period of service!
If there are indeed significant problems, then surely the correct way to investigate and solve them, is to spend time in the engine test cell where you are able to dispassionately assemble a credible and accurate data set and see what is really happening within the system.
I don’t think that changing the exhaust valves for heavier stainless items is a good idea, because in doing so, you are altering the thermal and dynamic behaviour of the whole valve train - that’s just my humble opinion, other may differ.
The point I have been trying to make about the LS7 is that it is a ‘state of the art design’ - as far as production pushrod V8 engines go, its introduction to the marketplace raised the bar in every way.
In the ‘old days’ , you could get away with, say, installing headers, changing the jets in the Holley, and then checking the colour of your plugs and tailpipe to see if you got the mixture correct - that was good enough!
Not today!
In the 'old days', you could change the stock valves for heavier items if you wanted to, without too much thought, because you were only asking the valve train to operate at around 4500rpm
Not today!
These 7000+ rpm - and I say + because you may well miss a shift somewhere down the road - these high rpm areas of operation are a universe away from the ‘old days’, and require lightweight components and designs which are state of the art, to ensure that the user can venture there on a daily basis.
In using the heavier one piece stainless valve you are setting out in a directly opposite path with regard to modern engineering design and good practice, from that pursued by the original GM team and that surely must make you pause and think hard .
I can see that you are removing the possibility of the two piece valve’s head breaking off , but just because a valve is of a one piece design does not mean that is immune to failure- valves fail for many reasons.
You always have to consider the modern valve train as a complete and carefully engineered system , and in changing the standard exhaust valve design in the LS7, you may be removing the local source of one problem only to create two new problems as yet undetected, somewhere upstream in the system.
Unless you have checked this change out rigorously, then you are in uncharted territory
I personally would not be confident to change something as crucial the exhaust valve design on my own engine unless I were able to see hard copy of test data indication the viability of such a change.
The ‘Rule of Thumb’ of yesteryear, has been replaced by the ‘Rule of Computer’ today - a huge amount of number crunching is necessary because of the complexity of today’s systems, and the mass of data required to accurately assess their performance.
The assembly of a large and accurate data set is the key to successful analysis, and that is why, with the best will in the world, it is difficult to tackle potential problems like this on internet forums.
In the broadest possible sense, public forums, whilst at first glance appearing to be an effective source of information, do, on deeper examination give rise to concerns, especially when trying assemble the quality of data necessary to draw firm conclusions about what, in any particular instance, is causing a problem
These doubts arise not on account of the credibility of the majority who care to post their experiences in the forums - honest and good people that they are.
Forums by virtue of their general and informal nature are, as we all know only too well, open to all shades of opinion and all manner of contribution, not all of which is wholly devoted to the search for knowledge and enlightenment !
If there is a problem with the valve train, then for instance, I can’t, for one minute, imagine that GM - noble institution that it is - posting up here to tell us all about it!
It goes without saying too, that there is a lot of money to be made, if thousands of LS7 owners are persuaded that there is a dire need for them to modify their valve gear ASAP.
The worthy Assayer of Dahlonega, Georgia, would, under the circumstances, probably say - “There’s Bronze in them thar ‘ills”
Whilst it may appear otherwise, unfortunately, the actual data sample provided by forum contributors is too small and to unfocussed to arrive at reliable conclusion as to what is the true source of the potential defect
As others have already pointed out, thousands of LS7s have been produced to date, and it is accurate to say that only a very small percentage of the total number of owners of LS7s post on this Corvette Forum.
Some forum members have had problems with the LS7 , others have not.
You could hazard a guess therefore, and say that most owners of LS7s don’t have problems with the engine - for whatever reason that may be.
Putting it another way - the Internet and Google in particular being what they are - perhaps, if there were very major problems with the LS7 valve train causing many catastrophic engine failures , would we not by now have amassed thousands of angry and anxious contributors to these threads?
I’m sure the press would be knocking at the door too!
Of course all this speculation does not make it any easier for those unfortunate guys who have had valve guide problems - it must be infuriating to say the least - I really feel for them.
For those who have not had problems, my advice, for what it is worth is - stay cool, hang loose, and ‘hasten slowly’
Valve guides do wear, no matter what you do - that is an inescapable fact automobile life- so the sky may indeed be falling, but probably not so fast, that it is going to end up in your lap.
Of course, someone somewhere out there will know all the answers - that‘s for sure!
Come out, come out - wherever you are!!
I am however, very pleased to play it, that's for sure - because its due respect where respect is due!
Most Automobile Manufacturers only attempt to produce engines for their own product range - and they would struggle commercially and technically to do otherwise .
The LS7 design team does, I think, deserve great credit, because they have managed to produce a product which has a very worthwhile foot in two camps - it has the potential to create revenue for GM from two separate streams of the business. It is used to power unit in GM’s own product line, and it has great sales potential in the Aftermarket business sector as well.
Here in the UK there are, sadly, very few C6 Z06 Corvettes on the road - probably 25 in total.
There are however, a lot more than 25 cars on the road here that are using the LS7 as a power unit!!
Monaro, TVR, Ultima, Gardner Douglas et al. - sharp eyed observers even claim to have noticed an LS7 under the hood of a pre-production test mule of a very exotic, recently released machine, produced by a certain UK based, high profile manufacturer, with very strong links to F1!
Thus, the LS7 design not only provides jobs and income for GM ‘s own employees. But in the broader marketplace it has talent enough in its configuration, to inspire others to create business, generate wealth, jobs and thus put food on the table for families.
Its success in the aftermarket is made possible because of its two major talents - it is able to be offered for sale at a price which makes it an attractive proposition to the aftermarket enthusiast and business owner alike, and its power/weight ratio makes it a technically an eminently suitable choice for those specialist applications which make the aftermarket what it is.
When you don’t have to worry greatly about costs, it is relatively easy to produce a power unit which is flashy and technically complex .
With the ‘cost monkey’ on your shoulder, things get a whole lot more difficult - ‘less is more’ so the mantra goes!
More power, for sure, but less weight and less in the budget to achieve that aim - that’s the regime that sorts the men from the boys, so to speak.
To design and produce an engine such as the LS7 and make it a commercial success into the bargain, is engineering at its best, and requires flair skill and discipline - to my mind the team who designed the LS7 possessed those characteristics by the bucket load, and therefore I pay respect to them .
Not too many enthusiasts motors out there, running M5 crate engines !
No wonder - too expensive, too complex, too heavy and a bit down on power into the bargain - far better off with an LS7!
Regarding the problems some members are reporting with valve train failures, it is really difficult for me to make an informed comment because I personally have not had any problems to date with the valve gear in my LS7.
Also, I don’t have personal access to the equipment and the data necessary to enable me to test the valve train design, and give an informed and accurate assessment of its performance.
Nothing on the face of this Earth is perfect, that’s for sure, so there may well be design flaws - I don‘t know.
You could play the devil’s advocate and say that it would be abnormal not to find some wear on the valve guides, after a period of service!
If there are indeed significant problems, then surely the correct way to investigate and solve them, is to spend time in the engine test cell where you are able to dispassionately assemble a credible and accurate data set and see what is really happening within the system.
I don’t think that changing the exhaust valves for heavier stainless items is a good idea, because in doing so, you are altering the thermal and dynamic behaviour of the whole valve train - that’s just my humble opinion, other may differ.
The point I have been trying to make about the LS7 is that it is a ‘state of the art design’ - as far as production pushrod V8 engines go, its introduction to the marketplace raised the bar in every way.
In the ‘old days’ , you could get away with, say, installing headers, changing the jets in the Holley, and then checking the colour of your plugs and tailpipe to see if you got the mixture correct - that was good enough!
Not today!
In the 'old days', you could change the stock valves for heavier items if you wanted to, without too much thought, because you were only asking the valve train to operate at around 4500rpm
Not today!
These 7000+ rpm - and I say + because you may well miss a shift somewhere down the road - these high rpm areas of operation are a universe away from the ‘old days’, and require lightweight components and designs which are state of the art, to ensure that the user can venture there on a daily basis.
In using the heavier one piece stainless valve you are setting out in a directly opposite path with regard to modern engineering design and good practice, from that pursued by the original GM team and that surely must make you pause and think hard .
I can see that you are removing the possibility of the two piece valve’s head breaking off , but just because a valve is of a one piece design does not mean that is immune to failure- valves fail for many reasons.
You always have to consider the modern valve train as a complete and carefully engineered system , and in changing the standard exhaust valve design in the LS7, you may be removing the local source of one problem only to create two new problems as yet undetected, somewhere upstream in the system.
Unless you have checked this change out rigorously, then you are in uncharted territory
I personally would not be confident to change something as crucial the exhaust valve design on my own engine unless I were able to see hard copy of test data indication the viability of such a change.
The ‘Rule of Thumb’ of yesteryear, has been replaced by the ‘Rule of Computer’ today - a huge amount of number crunching is necessary because of the complexity of today’s systems, and the mass of data required to accurately assess their performance.
The assembly of a large and accurate data set is the key to successful analysis, and that is why, with the best will in the world, it is difficult to tackle potential problems like this on internet forums.
In the broadest possible sense, public forums, whilst at first glance appearing to be an effective source of information, do, on deeper examination give rise to concerns, especially when trying assemble the quality of data necessary to draw firm conclusions about what, in any particular instance, is causing a problem
These doubts arise not on account of the credibility of the majority who care to post their experiences in the forums - honest and good people that they are.
Forums by virtue of their general and informal nature are, as we all know only too well, open to all shades of opinion and all manner of contribution, not all of which is wholly devoted to the search for knowledge and enlightenment !
If there is a problem with the valve train, then for instance, I can’t, for one minute, imagine that GM - noble institution that it is - posting up here to tell us all about it!
It goes without saying too, that there is a lot of money to be made, if thousands of LS7 owners are persuaded that there is a dire need for them to modify their valve gear ASAP.
The worthy Assayer of Dahlonega, Georgia, would, under the circumstances, probably say - “There’s Bronze in them thar ‘ills”
Whilst it may appear otherwise, unfortunately, the actual data sample provided by forum contributors is too small and to unfocussed to arrive at reliable conclusion as to what is the true source of the potential defect
As others have already pointed out, thousands of LS7s have been produced to date, and it is accurate to say that only a very small percentage of the total number of owners of LS7s post on this Corvette Forum.
Some forum members have had problems with the LS7 , others have not.
You could hazard a guess therefore, and say that most owners of LS7s don’t have problems with the engine - for whatever reason that may be.
Putting it another way - the Internet and Google in particular being what they are - perhaps, if there were very major problems with the LS7 valve train causing many catastrophic engine failures , would we not by now have amassed thousands of angry and anxious contributors to these threads?
I’m sure the press would be knocking at the door too!
Of course all this speculation does not make it any easier for those unfortunate guys who have had valve guide problems - it must be infuriating to say the least - I really feel for them.
For those who have not had problems, my advice, for what it is worth is - stay cool, hang loose, and ‘hasten slowly’
Valve guides do wear, no matter what you do - that is an inescapable fact automobile life- so the sky may indeed be falling, but probably not so fast, that it is going to end up in your lap.
Of course, someone somewhere out there will know all the answers - that‘s for sure!
Come out, come out - wherever you are!!
100%. Songman, another OUTSTANDING post my friend, WOW, great job, one of the best responses I have ever read on this topic!!!
Last edited by Mopar Jimmy; 09-04-2011 at 01:14 AM.