[Z06] LS7 Engine problems
11-01-2007, 01:35 AM
#21
Melting Slicks
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I mean come on, your statement implies this is 1950's tech and there is no excuse for any failures. The number of engine failures has been amazingly small. (judging by the ones reported on this forum)
11-01-2007, 01:59 AM
#22
Le Mans Master
11-01-2007, 04:05 AM
#23
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I personally havent seen all these rod issues, but then again I havent been here as long. As far as an LS2, the milder the cam the less problem your going to have with a valvetrain. I would fully expect a cammier motor to pop valves more frequently.
But I recall one thread that crystalizes what many of these cases are I beleive. One gentlemen jumping on the LS7 bash wagon referred to his 'freend' who was on his 3rd LS7, the prior two having had the infamous sucked a valve syndrome. One guy....3 engines.
Not hard to see what the problem truly is in that last scenario.
The internet has always overplayed things. At 3 years into this car, we would know by now if there was a wholesale problem.
11-01-2007, 05:18 AM
#24
Safety Car
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St. Jude Donor '08-'09-'10-'11-'12
Speaking of LS7 chicken little threads, look how this one just posted in General starts out:
http://forums.corvetteforum.com/show...ghlight=engine
http://forums.corvetteforum.com/show...ghlight=engine
11-01-2007, 10:36 AM
#30
I get a feeling some people here try to justify their 70k purchase that broke by saying "all cars have problems." I've been around high horsepower cars a long time and understand all of the nuances that come with them; but outright failure is a different issue all together. The pushrod motor has been around since the 50's, we should have rod, springs, and rocker arms figured out by now. It would be nice to know what the real MTBF for the Z is as it relates to the motor itself. I would also like to know the real number of Z06 owners on this board and how many have had total motor failure at < 20000 miles. If all Z owners (~12000?) visit this board then 15 total failures is a small percentage. If there are only 200 Z members on this board, then 15 failures is a very big deal at 7.5%.
A failure rate approaching 10% (just pulling a number out of a hat) would logically precipitate a campaign by GM for the sake of cost effectiveness. Moreover, we know from the Wixom builders that their max capacity is about 8,000 hand-built LS7s annually, which is close to the number of cars manufactured. If the failure number were anywhere near 10%, they'd need to be building a whole bunch of extra engines.
By way of illustration, a popular CF theory is that the valve springs are weak and this is causing an inordinate number of failures. If that were actually the case, it would be far more cost effective for GM to replace all valve springs, than it would be for them to replace 10-15% of failed LS7s. At mininum, one would have to ask why the valve spring design has not been modified in later engines, if the failure rate were so high? Wouldn't that be a "cheap fix?"
In addition, we never know how many of these cars are modified, and we have no clue how these cars have been used. Various polls posted here within the last few months have suggested a very high self-reported percentage of tunes, headers, intakes, etc. from CF Z06 forum dwellers. That is likely not a good representation of the general population of Z06 owners, and this forum is, no doubt, heavily over-represented with "hardcore" performance types.
When you are in a situation with nothing more than anecdotal reports to go on, and you have multiple, unknown variables, it is impossible to draw any conclusions, but you can make some logical inferences.
We really have no clue how many Z06 owners visit here. In addition, many of the "15" (or whatever number it is) reported failures here are from people reporting, "I know a friend of a friend whose engine melted down," or "my dealer told me........" In short, there is virtually no reliable documentation on this issue.
Last edited by Foosh; 11-01-2007 at 10:42 AM.
11-01-2007, 11:58 AM
#32
Burning Brakes
This is exactly the point, and a very good one. As a "self-proclaimed" (quoting Code Black), and actual scientist (I'll spare you the details on my credentials), the point is that it is impossible to tell what the actual percentage is from reports on this forum. However, there is fairly compelling circumstantial evidence to strongly suggest it is likely a rather small percentage.
A failure rate approaching 10% (just pulling a number out of a hat) would logically precipitate a campaign by GM for the sake of cost effectiveness. Moreover, we know from the Wixom builders that their max capacity is about 8,000 hand-built LS7s annually, which is close to the number of cars manufactured. If the failure number were anywhere near 10%, they'd need to be building a whole bunch of extra engines.
By way of illustration, a popular CF theory is that the valve springs are weak and this is causing an inordinate number of failures. If that were actually the case, it would be far more cost effective for GM to replace all valve springs, than it would be for them to replace 10-15% of failed LS7s. At mininum, one would have to ask why the valve spring design has not been modified in later engines, if the failure rate were so high? Wouldn't that be a "cheap fix?"
In addition, we never know how many of these cars are modified, and we have no clue how these cars have been used. Various polls posted here within the last few months have suggested a very high self-reported percentage of tunes, headers, intakes, etc. from CF Z06 forum dwellers. That is likely not a good representation of the general population of Z06 owners, and this forum is, no doubt, heavily over-represented with "hardcore" performance types.
When you are in a situation with nothing more than anecdotal reports to go on, and you have multiple, unknown variables, it is impossible to draw any conclusions, but you can make some logical inferences.
We really have no clue how many Z06 owners visit here. In addition, many of the "15" (or whatever number it is) reported failures here are from people reporting, "I know a friend of a friend whose engine melted down," or "my dealer told me........" In short, there is virtually no reliable documentation on this issue.
A failure rate approaching 10% (just pulling a number out of a hat) would logically precipitate a campaign by GM for the sake of cost effectiveness. Moreover, we know from the Wixom builders that their max capacity is about 8,000 hand-built LS7s annually, which is close to the number of cars manufactured. If the failure number were anywhere near 10%, they'd need to be building a whole bunch of extra engines.
By way of illustration, a popular CF theory is that the valve springs are weak and this is causing an inordinate number of failures. If that were actually the case, it would be far more cost effective for GM to replace all valve springs, than it would be for them to replace 10-15% of failed LS7s. At mininum, one would have to ask why the valve spring design has not been modified in later engines, if the failure rate were so high? Wouldn't that be a "cheap fix?"
In addition, we never know how many of these cars are modified, and we have no clue how these cars have been used. Various polls posted here within the last few months have suggested a very high self-reported percentage of tunes, headers, intakes, etc. from CF Z06 forum dwellers. That is likely not a good representation of the general population of Z06 owners, and this forum is, no doubt, heavily over-represented with "hardcore" performance types.
When you are in a situation with nothing more than anecdotal reports to go on, and you have multiple, unknown variables, it is impossible to draw any conclusions, but you can make some logical inferences.
We really have no clue how many Z06 owners visit here. In addition, many of the "15" (or whatever number it is) reported failures here are from people reporting, "I know a friend of a friend whose engine melted down," or "my dealer told me........" In short, there is virtually no reliable documentation on this issue.
I notice a lot of "rookies" buy these cars that have never been around high performance cars or understand them. They report "problems" that actually just come with the high horsepower/high performance territory. I feel they are comparing it to other 70k cars and expecting the same results instead of correctly comparing it to other cars that pull the same performance numbers. Have they seen the high maintenance issues of the Ferrai and Lambo and 3x+ the cost??? I've seen posts where people complain about having to replace tires at 10-15k miles. Obviously they don't understand what Z rated tires mean or know how to interpret the numbers on the tire itself that tell you this information. I've also heard rear end complaints when turning slowly. Obviously they don't understand how a rear-end that can handle this much HP works. Then there are the people that report "shaking" at idle. Once again, 15 years ago it took a lot of effort to get a 500hp out of a naturally aspirated small block, and it would have shook you to death. There is obviously no knowledge of what cam profiles, high flow heads, and high flow intakes do to idle conditions. You would also be very far from 25MPG. There are many more to list but we all know what they are..
Hopefully the negative image that some cast is just the result of being a popular message board that turns into the complaint destination.
11-01-2007, 11:59 AM
#33
Burning Brakes
This is exactly the point, and a very good one. As a "self-proclaimed" (quoting Code Black), and actual scientist (I'll spare you the details on my credentials), the point is that it is impossible to tell what the actual percentage is from reports on this forum. However, there is fairly compelling circumstantial evidence to strongly suggest it is likely a rather small percentage.
A failure rate approaching 10% (just pulling a number out of a hat) would logically precipitate a campaign by GM for the sake of cost effectiveness. Moreover, we know from the Wixom builders that their max capacity is about 8,000 hand-built LS7s annually, which is close to the number of cars manufactured. If the failure number were anywhere near 10%, they'd need to be building a whole bunch of extra engines.
By way of illustration, a popular CF theory is that the valve springs are weak and this is causing an inordinate number of failures. If that were actually the case, it would be far more cost effective for GM to replace all valve springs, than it would be for them to replace 10-15% of failed LS7s. At mininum, one would have to ask why the valve spring design has not been modified in later engines, if the failure rate were so high? Wouldn't that be a "cheap fix?"
In addition, we never know how many of these cars are modified, and we have no clue how these cars have been used. Various polls posted here within the last few months have suggested a very high self-reported percentage of tunes, headers, intakes, etc. from CF Z06 forum dwellers. That is likely not a good representation of the general population of Z06 owners, and this forum is, no doubt, heavily over-represented with "hardcore" performance types.
When you are in a situation with nothing more than anecdotal reports to go on, and you have multiple, unknown variables, it is impossible to draw any conclusions, but you can make some logical inferences.
We really have no clue how many Z06 owners visit here. In addition, many of the "15" (or whatever number it is) reported failures here are from people reporting, "I know a friend of a friend whose engine melted down," or "my dealer told me........" In short, there is virtually no reliable documentation on this issue.
A failure rate approaching 10% (just pulling a number out of a hat) would logically precipitate a campaign by GM for the sake of cost effectiveness. Moreover, we know from the Wixom builders that their max capacity is about 8,000 hand-built LS7s annually, which is close to the number of cars manufactured. If the failure number were anywhere near 10%, they'd need to be building a whole bunch of extra engines.
By way of illustration, a popular CF theory is that the valve springs are weak and this is causing an inordinate number of failures. If that were actually the case, it would be far more cost effective for GM to replace all valve springs, than it would be for them to replace 10-15% of failed LS7s. At mininum, one would have to ask why the valve spring design has not been modified in later engines, if the failure rate were so high? Wouldn't that be a "cheap fix?"
In addition, we never know how many of these cars are modified, and we have no clue how these cars have been used. Various polls posted here within the last few months have suggested a very high self-reported percentage of tunes, headers, intakes, etc. from CF Z06 forum dwellers. That is likely not a good representation of the general population of Z06 owners, and this forum is, no doubt, heavily over-represented with "hardcore" performance types.
When you are in a situation with nothing more than anecdotal reports to go on, and you have multiple, unknown variables, it is impossible to draw any conclusions, but you can make some logical inferences.
We really have no clue how many Z06 owners visit here. In addition, many of the "15" (or whatever number it is) reported failures here are from people reporting, "I know a friend of a friend whose engine melted down," or "my dealer told me........" In short, there is virtually no reliable documentation on this issue.
Any statistician worth his P value would tell you that there is no scientific value to any conclusions made based on "data" presented on this forum.
I have posted my problem because there may be valuable lessons to be learned by everyone. I have throughly enjoyed my street and track driving and expect the motor issue to be resolved long before the warm weather returns.
The Z will be back on the track again!
Dean
11-01-2007, 12:48 PM
#34
Le Mans Master
11-01-2007, 02:27 PM
#36
Melting Slicks
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11-01-2007, 04:05 PM
#37
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11-01-2007, 05:15 PM
#38
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The sounds you are hearing are not chicken little the sky is falling, but are the sounds of your valvetrain, needle bearings falling into the oilpan, a miss in your cylinders, the roof hitting the pavemrnt when it flys off and the laughing of the GM salesman who just took us for 80,000. Is that scientific enough?
11-01-2007, 05:24 PM
#39
Burning Brakes
The sounds you are hearing are not chicken little the sky is falling, but are the sounds of your valvetrain, needle bearings falling into the oilpan, a miss in your cylinders, the roof hitting the pavemrnt when it flys off and the laughing of the GM salesman who just took us for 80,000. Is that scientific enough?
