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2017 Corvette Grand Sport blown engine

 
Old 06-12-2019, 07:05 AM
  #101  
Tom Letkewicz
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I am not an engineer but you can't tell me that when they set the red line at 6500 that the true red line is not higher. I relate this to the gas gauge, when you hit empty on newer cars empty is really not empty a cushion is built in. When there is a highway off ramp listed at 30mph, one can definitely go 40mph without damage. If dipping into the supposed redline for less than a second is enough to blow this "bullet-proof" engine then this will be the last corvette I ever consider buying. I buy expensive tools with warranties that state if I drop the tool and it breaks its covered. I haven't heard back from GM yet but I know what the answer will be. Is this "high performance" car only good for traveling around the town? Sorry, this whole thing just doesn't make sense to me.
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Old 06-12-2019, 07:17 AM
  #102  
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Originally Posted by golden2husky View Post
Well, I am also an honest person, but learned long ago not to be stupidly honest. And this was stupidly honest. That said, those over-revs, no matter how minor, give the corporation the wiggle room to deny a claim. And true to form, the classic short-sighted American business mentality reared its ugly head and denied the claim for a couple hundred RPM over for what, a few seconds? Honda would have picked up this tab, even if you were 5,000 miles out of warranty.
I agree, that was my mistake--I should have fabricated a story. I even had others tell me to make up a story. But being the honest Abe, I figured it was a corvette, GM's crown jewel how could they deny me. The owners manual explains how to set car up for track, and warranty is not void for HPD events. So I thought I was good. Lesson learned. I like the corvette, GM customer service is disappointing.
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Old 06-12-2019, 08:34 AM
  #103  
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There has to be something “more” to this story . Maybe not even known to the OP . I am quite curious at the outcome .

i am not a C7 owner yet , but this is steering me more to the Cayman.
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Old 06-12-2019, 10:42 AM
  #104  
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Certainly not turning out the way any Corvette owner would have expected. Really makes the argument that GM is looking for reasons to deny high dollar warranty claims.
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Old 06-12-2019, 10:45 AM
  #105  
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Originally Posted by Tom Letkewicz View Post
I am not an engineer but you can't tell me that when they set the red line at 6500 that the true red line is not higher. I relate this to the gas gauge, when you hit empty on newer cars empty is really not empty a cushion is built in. When there is a highway off ramp listed at 30mph, one can definitely go 40mph without damage. If dipping into the supposed redline for less than a second is enough to blow this "bullet-proof" engine then this will be the last corvette I ever consider buying. I buy expensive tools with warranties that state if I drop the tool and it breaks its covered. I haven't heard back from GM yet but I know what the answer will be. Is this "high performance" car only good for traveling around the town? Sorry, this whole thing just doesn't make sense to me.
The engine didnt blow from dipping into the redline for less than a seconds once. When you over rev the engine even for a second, damage is done to the rotating assembly. it may not become apparent at the time, but its there. How many times before this event have you tracked the car? Has it been over-revved prior to this event, even just briefly by 100 RPM? The engine could have let go just as easy while driving down the street once the damage was done from a previous over-rev, yours just happened to occur while on the track. Either way the cause was an over-rev.


How many times have you seen a nascar engine let go 10-100+ laps after the driver over-revved it on a restart? Or they play in car audio saying the motor is blowing up because they can feel the less power or its not making the rpms it was prior, yet they go many more laps before it actually blows up.

Last edited by born2beS12; 06-12-2019 at 10:48 AM.
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Old 06-12-2019, 10:56 AM
  #106  
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Originally Posted by JALLEN4 View Post
Some people just make some pathetic attempts to play "Big Man". I certainly don't speak for the dealer who is actually involved but I also can assure you I speak for a lot of dealers.

When you show up with the attorney, work stops! You have no right to film anything without my permission...ever! Who do you think you are to demand my communications with anybody...ever! Your obnoxious actions would assure my telling you to take your broken car and pathetic butt out of my store immediately...forever!

People who act like actual reasonable human beings get exactly what they are owed at GM dealerships 99.9% of the time. But, dealers have enough money they are not going to be intimidated by some jerk and his two bit ambulance chaser!
LOL you were saying? Unless the OP isn't telling us about massive over revs, the pics he did show us should not be enough to deny a warranty claim. He can probably win this in court but it will be costly and time intensive - gm knows this because they are trying to dodge their warranty obligations, just like with the GS/z06 wheels and the A8.
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Old 06-12-2019, 11:02 AM
  #107  
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Originally Posted by Tom Letkewicz View Post
I am not an engineer but you can't tell me that when they set the red line at 6500 that the true red line is not higher. .
I'm with you on this point. Its not like at 6499 the engine is fine and at 6501 it blows up. They would definitely build in some kind of buffer for slight temporary over-rev.
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Old 06-12-2019, 11:07 AM
  #108  
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Seems like people keep forgetting about the over-rev on downshifts. No way to protect from that. The amount of damage seems to be from that situation. Amplified by the extreme speeds you can reach at the track.
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Old 06-12-2019, 11:10 AM
  #109  
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Originally Posted by Zjoe6 View Post
Seems like people keep forgetting about the over-rev on downshifts. No way to protect from that. The amount of damage seems to be from that situation. Amplified by the extreme speeds you can reach at the track.
Or that this was probably not a first time occurence and its just when it became apparent.
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Old 06-12-2019, 11:26 AM
  #110  
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Originally Posted by born2beS12 View Post
Or that this was probably not a first time occurence and its just when it became apparent.
Very possible.
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Old 06-12-2019, 12:35 PM
  #111  
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OP - TOM
JMO - I've been wrenching motors/cars and airplanes for a long time. GM: If you build a "performance engine" that can't tickle the redline now and then you built a POS motor. True performance engines are overbuilt as are airplanes because when you get close to the limits there isn't any room for error or inferior engineering and or parts. I'm pretty sure the GM engineers at the performance build center and the GM tech center built a solid motor that in testing banged the redline, over, and over many, many times. I think it would be different if the vid showed several events way-way, and I mean WAY into the 7000 range; but at 66/6700 RPM with a 6500 factory redline ?? BS this was a component failure that at sometime down the road would have showed up -- lets just say the engine was pregnant and was going to hatch at some time and not in a good way. For goodness-sakes my Acura V-6 tags the redline (6600) on the nose every-time you wind it up and I'm pretty sure Honda still has a 100K+ in mind for reliability. Tom, unfortunately honesty sometimes doesn't pay, but the real problem I see is you had a defective part in a normally well built and engineered motor, but you had a paper-pusher and a ***** for a engineer field rep that could see a clear way for a denial. I just bought a new 19 Z and I will really be cognizant about that RED LINE after how you were treated by GM. Shame on them -- "track ready" my ***!! Rant over
Best of luck getting a new motor
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Old 06-12-2019, 01:29 PM
  #112  
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Originally Posted by kennyjames21 View Post
LOL you were saying? Unless the OP isn't telling us about massive over revs, the pics he did show us should not be enough to deny a warranty claim. He can probably win this in court but it will be costly and time intensive - gm knows this because they are trying to dodge their warranty obligations, just like with the GS/z06 wheels and the A8.
You are right! The OP shows us a film covering minutes of a cars life that has over 5,000 miles on it. The minutes just happen to occur on a race track which apparently was not the first time it was used for that purpose. GM, who designed the engine, built it, and warranties it, looks at the tear down and has the audacity to say it was an over-rev situation.

Now you, with your extensive experience with these matters, calls BS and knows GM is simply trying to dodge their responsibility. But, you have a lot of company chiming in. Never seen the car nor really know anything in reality but not their money so GM should certainly pay!

Now is the time though to find that attorney everyone has on retainer!
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Old 06-12-2019, 03:45 PM
  #113  
Tom Letkewicz
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Originally Posted by kenownr View Post
OP - TOM
JMO - I've been wrenching motors/cars and airplanes for a long time. GM: If you build a "performance engine" that can't tickle the redline now and then you built a POS motor. True performance engines are overbuilt as are airplanes because when you get close to the limits there isn't any room for error or inferior engineering and or parts. I'm pretty sure the GM engineers at the performance build center and the GM tech center built a solid motor that in testing banged the redline, over, and over many, many times. I think it would be different if the vid showed several events way-way, and I mean WAY into the 7000 range; but at 66/6700 RPM with a 6500 factory redline ?? BS this was a component failure that at sometime down the road would have showed up -- lets just say the engine was pregnant and was going to hatch at some time and not in a good way. For goodness-sakes my Acura V-6 tags the redline (6600) on the nose every-time you wind it up and I'm pretty sure Honda still has a 100K+ in mind for reliability. Tom, unfortunately honesty sometimes doesn't pay, but the real problem I see is you had a defective part in a normally well built and engineered motor, but you had a paper-pusher and a ***** for a engineer field rep that could see a clear way for a denial. I just bought a new 19 Z and I will really be cognizant about that RED LINE after how you were treated by GM. Shame on them -- "track ready" my ***!! Rant over
Best of luck getting a new motor
Thank you for your post. This is exactly what I am trying to convey when I say that redline at 6500 has to have a buffer. As to a post questioning how many times I have redlined the engine the answer is watch the video. I was honest about using the car on track and I am being honest when I say, I have never missed a shift from 4th to 2nd or 4th to 1st. I have never excessively over revved this engine. The video shows I dipped into redline coming off high speeds, but that dip was small and very short. As this post states, if this engine is not built with a cushion into redline then the engine is to fragile to ever take on track and that should be clearly pointed out in the owners manual.

Thanks again for the post and all other folks that are supportive of my position.
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Old 06-12-2019, 06:23 PM
  #114  
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Sorry to hear of your troubles!
An earlier post mentioned something about the dealership able to see the historical high revs on a car. Can i find that out myself? Just curious.
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Old 06-12-2019, 07:10 PM
  #115  
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Originally Posted by IAIA View Post
Sorry to hear of your troubles!
An earlier post mentioned something about the dealership able to see the historical high revs on a car. Can i find that out myself? Just curious.
I asked the dealership to provide me with the ECM log. They had no idea what I was talking about but stated that this was a fair request and they would contact GM to ask about this. GM told the dealership all they needed (GM) was the VIN of the car and the engine needed to be torn down to determine fault. At this point I still do not know how they came to the conclusion that the car was over revved. No log or documentation of over revving has been provided to me yet. Still waiting.
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Old 06-12-2019, 08:01 PM
  #116  
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I have hit the redline a few times and the engine backs right off. So if it is over revved is there not something wrong with the rev limiter, I am not a mechanic so I dont know
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Old 06-12-2019, 08:57 PM
  #117  
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Originally Posted by Jmhornz71 View Post
I have hit the redline a few times and the engine backs right off. So if it is over revved is there not something wrong with the rev limiter, I am not a mechanic so I dont know
Once again, the rev limiter only affects throttle input (I assume it works by killing ignition to prevent over reving). Over reving due to downshifting at too high a speed/too low a gear.. well not much will protect against that
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Old 06-12-2019, 09:23 PM
  #118  
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Originally Posted by KenHorse View Post
Once again, the rev limiter only affects throttle input (I assume it works by killing ignition to prevent over reving). Over reving due to downshifting at too high a speed/too low a gear.. well not much will protect against that
Thanks for the reply, I have only hit the redline on the way up not downshifting
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Old 06-12-2019, 09:48 PM
  #119  
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interestingly, theres also a rev limit to the rev match function on the M7. no matter what you do, it wont peg the engine above 5200 rpm, if i remember correctly. its somewhere right around there, anyway. which suggests a certain.. conservatism, if ya ask me.

best of luck to OP. chevy seems to play very close to the vest on these things. challenge them with your logged data though, it doesnt seem like the engine went anywhere near too high. it almost seems like theyre just rendering a generic/default judgement. in this country thats called guilty until proven innocent and thats not how its done, in america. **** 'em. burden of proof is on the plaintiff BUT youve got data to back up the fact that theyre wrong...
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Old 06-12-2019, 10:43 PM
  #120  
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GM powertrain specifies the maximum recommended RPM as 6600 for the LT1 and LT4. How much over this the typical LT1/LT4 can go without damage is another question as is how strictly GM wants to stick with the specified limit. If they want to play hardball, they can (and perhaps are) stating that 6,500 is marked redline on the tach giving you a 100 RPM buffer before hitting maximum recommended and you went beyond this RPM. I wouldn't care for that reasoning but I wouldn't want to try to fight it in court.

Since you have the PDR data, you can download Pi Toolbox from Cosworth and show a graph of the precise RPM for any PDR data that you have. It would be interesting to see what Pi Toolbox shows for the actual RPM compared to the peak RPM on the LCD display tach. I suspect that the ECM captures the maximum RPM the engine has seen over its lifetime and that may not have been at this track event or on this specific lap.

Here is a screen capture of Pi Toolbox. Moving the cursor across the graph will show the precise value in the data box for that point on the timeline.


Last edited by NSC5; 06-12-2019 at 10:51 PM.
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