C7 engine problems, would you by a C7 today?
Advanced
Joined: Dec 2012
Posts: 52
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All are actually, just none are admitting publicly the extent of this issue as the fear, and well founded, is that there will be a backlash of those NOT buying new and keeping older port injection vehicles. SO at all cost's, this is downplayed. Now, on Toyota/Lexus/Audi/VW and more are adding back in small port fuel injectors, but as they are too little as far as fuel contact, they have limited actual reduction in the coking. (some coking will always occur W/GDI due to cylinder back-fill for EGR emulation, but that is minor compared to what comes from the PCV system) What this does do is create a situation of now allowing fuel to be present during the compression stroke, and that increases the rate of detonation and thus greater KR which decreases both power and fuel economy as most GDI engines now are 11.5:1 or higher CR (Audi is running 19:1 in the lab!!!!) so that is not a good solution to date. Same with multiple fuel events (triggering a momentary spray from the DI injectors when the intake valve is open). The best preventative is always run a premium full synthetic oil, never a "blend" like the Dexos blend or a conventional is worse yet. All manufacturers recommend a top tier fuel, but after 7 years of study, we see little to no impact over generic fuels as the detergent is no longer showering and cooling/cleaning the valves as with port injection.. so this is not helping. Using a seafoam type solvent based cleaner while engine is running is causing damage in most cases and NOT to be used (no matter what they claim, we always see scouring to the pistons and cylinders from these hard crystaline type deposits are like pouring some sand into the cylinder as the high heat range these valves now run at bake the deposits over time to very hard abrasive particles.
Defeating the PCV systems functions like breather/tanks will cause the engine to wear far more rapidly by leaving most all of the damaging combustion by-products in the crankcase contaminating the engine oil, so only a truly effective separation system will stop most of this from occurring. Elite E2-X or ColoradoSPeed's separators.
Absolutely 100% correct. This affects every auto maker in the World, here are pictures posted by techs and DIY people from around the World:
https://www.google.com/search?q=dire...w=1600&bih=775
These are NOT your old port injection engines that eliminated these issues that used to be present in carbureted engines of old, it is now back and many times more severe than ever.
Those mushroom deposits show how these are also wearing the valve guides prematurely as with each cycle of the valve the stem entering the guide is pulling some into the guide and wearing the softer guide.
As more mile accumulate and we study more, we find more issue long term when to begin with we assumed it was just degradation in power and economy/efficiency from the flow disruption, but were seeing far more issues.
The true OEM solution is still a few years away, it involves an external separation systems like those mentioned, but that never need to be end user emptied. That design is complete and proven to meet all emission standards, but Patent is in the Provisional stage currently before it is presented to the Automakers.
Excellent activity here!!! Great understanding Muncie!
Defeating the PCV systems functions like breather/tanks will cause the engine to wear far more rapidly by leaving most all of the damaging combustion by-products in the crankcase contaminating the engine oil, so only a truly effective separation system will stop most of this from occurring. Elite E2-X or ColoradoSPeed's separators.
Absolutely 100% correct. This affects every auto maker in the World, here are pictures posted by techs and DIY people from around the World:
https://www.google.com/search?q=dire...w=1600&bih=775
These are NOT your old port injection engines that eliminated these issues that used to be present in carbureted engines of old, it is now back and many times more severe than ever.
Those mushroom deposits show how these are also wearing the valve guides prematurely as with each cycle of the valve the stem entering the guide is pulling some into the guide and wearing the softer guide.
As more mile accumulate and we study more, we find more issue long term when to begin with we assumed it was just degradation in power and economy/efficiency from the flow disruption, but were seeing far more issues.
The true OEM solution is still a few years away, it involves an external separation systems like those mentioned, but that never need to be end user emptied. That design is complete and proven to meet all emission standards, but Patent is in the Provisional stage currently before it is presented to the Automakers.
Excellent activity here!!! Great understanding Muncie!
Racer
Joined: Feb 2015
Posts: 331
Likes: 38
From: Florham Park NJ
This is starting to look like another thread about carbon deposits, haven't we beat this to death already? The OP was only asking about C7 issues not an education on GDI engines but again we have retailers trying to sell their products. SMFH, we all know its a problem and we all know a catch can may help so leave it at that. He was asking about C7 problems not problems all GDI's have.
Last edited by jdarc1; Jan 14, 2016 at 07:10 PM.
Melting Slicks
Joined: Dec 2004
Posts: 3,120
Likes: 119
St. Jude Donor '10
jdarc, as this is mainly the most severe issue these all have, I was just answering questions on it. If it is not a concern for you, then that's great, but many here are not versed on this and they are looking for answers.
Advanced
Joined: Dec 2012
Posts: 52
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Should not be an issue as the build up is on the backsides of the valves so should not affect PTV clearance. What is an issue is if a large chunk breaks loose and get trapped between the valve and seat, then PTV contact will bend a valve.
jdarc, as this is mainly the most severe issue these all have, I was just answering questions on it. If it is not a concern for you, then that's great, but many here are not versed on this and they are looking for answers.
jdarc, as this is mainly the most severe issue these all have, I was just answering questions on it. If it is not a concern for you, then that's great, but many here are not versed on this and they are looking for answers.
I am signing out now. I think the OP was looking for more general comments and I may have led this thread astray.
Drifting
Joined: Oct 2005
Posts: 1,729
Likes: 62
From: South Lyon MI
Originally Posted by MikeLsx
Just because the last generation corvette didn't have problems doesn't mean this one wont.
GM introduced a lot of new tech to the corvette. Stuff like direction injection (which is proven to be problematic), AFM, more electronics,more dry sumps, more dealership techs that dont understand corvettes etc..
I would say the best engine GM made in recent history is the LS3. Was port injection and didnt have any of the fuel saving crap the LT1 has. It was simple to take apart also.
If i wanted to keep my corvette for many many years. I would be tempted to get a Ls7 engine swap instead of trying to make the LT1 better.
with all that said. I do feel however the c7 is probably a very reliable car short term. I think my corvette will be somewhat problem feel until the next generation comes out.
GM introduced a lot of new tech to the corvette. Stuff like direction injection (which is proven to be problematic), AFM, more electronics,more dry sumps, more dealership techs that dont understand corvettes etc..
I would say the best engine GM made in recent history is the LS3. Was port injection and didnt have any of the fuel saving crap the LT1 has. It was simple to take apart also.
If i wanted to keep my corvette for many many years. I would be tempted to get a Ls7 engine swap instead of trying to make the LT1 better.
with all that said. I do feel however the c7 is probably a very reliable car short term. I think my corvette will be somewhat problem feel until the next generation comes out.
Just saying.
Drifting
Joined: Dec 2012
Posts: 1,630
Likes: 203
From: MI
Ya I understand the Ls7 had a few problems. But i was talking about the LS3 in regards to being the best engine GM made recently.
It doesn't have any of that fuel saving crap, and no GDI. Its a more proven engine.
in regards to the LS7, i would take that engine over the LT1 any day. the LT1 problems are going to be from trying to get better fuel economy(adding more BS to the engine). the Ls7 problems were design flaw.
Last edited by MikeLsx; Jan 17, 2016 at 08:25 AM.
Drifting
Joined: Oct 2005
Posts: 1,729
Likes: 62
From: South Lyon MI
Originally Posted by MikeLsx
oh give me a break. There are reported engine failures across the board from all makes. specially at the track.
Ya I understand the Ls7 had a few problems. But i was talking about the LS3 in regards to being the best engine GM made recently.
It doesn't have any of that fuel saving crap, and no GDI. Its a more proven engine.
in regards to the LS7, i would take that engine over the LT1 any day. the LT1 problems are going to be from trying to get better fuel economy(adding more BS to the engine). the Ls7 problems were design flaw.
Ya I understand the Ls7 had a few problems. But i was talking about the LS3 in regards to being the best engine GM made recently.
It doesn't have any of that fuel saving crap, and no GDI. Its a more proven engine.
in regards to the LS7, i would take that engine over the LT1 any day. the LT1 problems are going to be from trying to get better fuel economy(adding more BS to the engine). the Ls7 problems were design flaw.
My point is that people will say theirs is better than this new fangled tech 10 times out of 10. You're no exception. You should look into credible sources like Danny Popp who claim to have NEVER seen a stock LS7 WITHOUT head issues.
My LT1 puts down 417HP in stock trim. 443 whp with a tune. I've never seen that with a stock LS3. Not to mention how much nicer the C7 is overall. Talk about swapping a LS3 into a C7 is flat out stupid.
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Drifting
Joined: Dec 2012
Posts: 1,630
Likes: 203
From: MI
The afm can be tuned out. No biggie. If you really are paranoid, you can replace the lifters. DI makes more power. By a fair margin or I doubt the C7.R would use it. I'll clean the valves every now and again after I have A great catch can I'm still a good bit ahead of what it would cost to make the extra power between a LS3 and LT1.
My point is that people will say theirs is better than this new fangled tech 10 times out of 10. You're no exception. You should look into credible sources like Danny Popp who claim to have NEVER seen a stock LS7 WITHOUT head issues.
My LT1 puts down 417HP in stock trim. 443 whp with a tune. I've never seen that with a stock LS3. Not to mention how much nicer the C7 is overall. Talk about swapping a LS3 into a C7 is flat out stupid.
My point is that people will say theirs is better than this new fangled tech 10 times out of 10. You're no exception. You should look into credible sources like Danny Popp who claim to have NEVER seen a stock LS7 WITHOUT head issues.
My LT1 puts down 417HP in stock trim. 443 whp with a tune. I've never seen that with a stock LS3. Not to mention how much nicer the C7 is overall. Talk about swapping a LS3 into a C7 is flat out stupid.
We have to mod the factory PCV system to stop carbon build up?
we have to open the engine up to clean it, so we can keep making advertised power and fuel consumption ?
the LT1 is more powerful, but it has drawbacks the LS3 never had.
I would never swap a LS3 into my corvette. I will just sell it for something faster or better when the time comes.
Last edited by MikeLsx; Jan 17, 2016 at 09:09 AM.
Instructor
Joined: Jun 2015
Posts: 176
Likes: 13
From: PA
You should buy a C7 Corvette because that is all BS and maybe a few engine problems or other issues . Which happens with every single car manufacture when they introduce a newer model of there car or totally new one . I own a 2015 C7 Corvette ZO6 and i have had absolutly no problems or issues whatsoever. The C7 Corvette is so F#@%ing AWESOME ! The C7 ZO6 is F#@%ing AWESOME X 10 which may result in loss of drivers license . Dont listen to people hating with hyped up or incorrect false information 
.
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Drifting
Joined: Oct 2005
Posts: 1,729
Likes: 62
From: South Lyon MI
Originally Posted by MikeLsx
so we might have to void our engine warranty to "tune" out AFM? Even at the point of tuning it out, its still there.
We have to mod the factory PCV system to stop carbon build up?
we have to open the engine up to clean it, so we can keep making advertised power and fuel consumption ?
the LT1 is more powerful, but it has drawbacks the LS3 never had.
I would never swap a LS3 into my corvette. I will just sell it for something faster or better when the time comes.
We have to mod the factory PCV system to stop carbon build up?
we have to open the engine up to clean it, so we can keep making advertised power and fuel consumption ?
the LT1 is more powerful, but it has drawbacks the LS3 never had.
I would never swap a LS3 into my corvette. I will just sell it for something faster or better when the time comes.
Drifting
Joined: Dec 2012
Posts: 1,630
Likes: 203
From: MI
Drifting
Joined: Oct 2005
Posts: 1,729
Likes: 62
From: South Lyon MI
Originally Posted by MikeLsx
better believe every new car i get into is faster than the last.
Just make sure you do all your racing before your valves are caked with carbon. .
Just make sure you do all your racing before your valves are caked with carbon. .
Burning Brakes
Joined: Mar 2015
Posts: 875
Likes: 311
From: Sundance WY
I have a 14 Z51 coupe the 900th built..... you know the first year when none of the bugs are worked out..... 20,000 miles now... ZERO warranty repairs.... go figure.... 4 oil changes.... end of story....
Love this car
Love this car
Drifting
Joined: Dec 2012
Posts: 1,630
Likes: 203
From: MI
Heel & Toe
Joined: Nov 2015
Posts: 15
Likes: 0
[QUOTE=rrsperry;1591289864]Ok, here goes..
Where do I find the info about GM paying for the 1st oil change?
Only cars with the dry sump oiling system, (Z06, and Z51 cars) are required to get the oil changed at 500 miles. Chevy is paying for it, so who cares...
Where do I find the info about GM paying for the 1st oil change?
Only cars with the dry sump oiling system, (Z06, and Z51 cars) are required to get the oil changed at 500 miles. Chevy is paying for it, so who cares...
Drifting
Joined: Dec 2012
Posts: 1,630
Likes: 203
From: MI
I can understand that a engine at 80k miles isnt going to run like it did at 5k miles. but being down 20-30HP about 20k miles is simply stupid.
I look forward to seeing what happens to these LT1 engines as time goes on. really interesting topic for a car guy.
Last edited by MikeLsx; Jan 17, 2016 at 06:12 PM.
Melting Slicks
Joined: Dec 2004
Posts: 3,120
Likes: 119
St. Jude Donor '10
Well from the info people spread on here about this issue. They make it out to seem that by 20k miles your valves will be screwed.
I can understand that a engine at 80k miles isnt going to run like it did at 5k miles. but being down 20-30HP about 20k miles is simply stupid.
I look forward to seeing what happens to these LT1 engines as time goes on. really interesting topic for a car guy.
I can understand that a engine at 80k miles isnt going to run like it did at 5k miles. but being down 20-30HP about 20k miles is simply stupid.
I look forward to seeing what happens to these LT1 engines as time goes on. really interesting topic for a car guy.
We don't see any damage to the valves themselves at 20k miles, only the guides are showing wear by them. When cleaned, they are as good as new. And those that have installed a good system like the ones I reference and then every 10-15k miles do a upper induction cleaning service so far are seeing very little build up. There will always be some due to the back-swirl of exhaust gasses that do hit the valve backsides to emulated the function of a EGR, but that is a small contribution to the coking.
We do see some scouring to piston skirts and cylinder walls in higher mileage engines from some of the hard deposits getting forced between the piston and cylinder wall when they comes loose, but the valves themselves have always been in great shape when cleaned and inspected. Power degradation s another story though.
GDI is so far advance than port injection from a power and efficiency standpoint though...no way a LS engine could run 11.5:1 CR without race gas, yet the LT1 can on 91-93 octane no problem. It is just the coking issue itself.