My GT3 engine just blew up
11-28-2016, 08:32 PM
#256
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Just throwing it out there. Have been following both this thread and the other on similar subject.
Could the engine failures have something to do with that those that DONT drive in auto mode short shift a little more and put less stress on internals than those that drive in Auto and therefore more often hit redline.
I think I've heard Trakcar say that he short shifts his car.
Now Deacon saying the same thing?
Would be interesting to know if Manifold and those that have E and F engines that have held up fine is doing more driving in Manual and short shift a little before redline?
Could the engine failures have something to do with that those that DONT drive in auto mode short shift a little more and put less stress on internals than those that drive in Auto and therefore more often hit redline.
I think I've heard Trakcar say that he short shifts his car.
Now Deacon saying the same thing?
Would be interesting to know if Manifold and those that have E and F engines that have held up fine is doing more driving in Manual and short shift a little before redline?
Some cars that blew up were not tracked much or at all, and it's impossible to spend any meaningful time near read line on public roads without going to jail or dying. So it's not high-revs that's killing these engines.
I cannot tell if this wear is from stress or abrasion, but typically in machines, lower speed causes abrasion wear (easier to break oil film at lower speed) and higher speed causes stress wear (forces are square of speed). This does look more like abrasion to me, but it can be that stress first breaks the coating and then the rest is done by abrasion - who knows.
I know of at least two other F-engine cars that track more than I do and drive as hard.
I'll report when mine blows up.
By the way, shifting manually, unless you are short-shifting really low, may be worse for the engine because
1) automatic will never bounce against the red line, and the engine spends milliseconds there per shift, and it does not redline in all gears either. When shifting manually, just one delayed shift with bounce of the red line can cause more time at peak revs than hundreds of automatic shifts.
2) when downshifting, automatic seems to figure out the latest moment it can downshift, sometimes even after turn entry, thus keeping engine at lower revs. When shifting manually, drivers tend to try to get done with downshifting earlier, thus resulting in higher revs.
But that's a moot point.
11-28-2016, 10:09 PM
#257
Nordschleife Master
Originally Posted by rm21
I believe Orthojoe drives in auto as well, but I agree it is a relevant variable. If I end up with another GT3 I plan to short shift.
11-28-2016, 10:31 PM
#258
Three Wheelin'
We are still in the process of getting an approval for a new engine. Porsche of Melbourne has allowed me access to take pictures of the tear down but they don't help much with root cause. I only completed one session at Daytona and wear was pretty bad on the #6 cam lobe and follower. Honestly I don't know if Daytona hastened or caused the failure but what Gavin says makes sense.
This is why I posted earlier to see if we could get data on which cars reporting issues are tracked clockwise v. Counter and which cylinders are coming up short. Maybe this could shed light on our problem. Maybe we can get enough data to eliminate this variable out of the mix or maybe it does show some correlation.
11-28-2016, 10:34 PM
#259
Rennlist Member
Almost always Auto on track, 17K miles total, probably about 3K on track and the rest is driving to track on a highway and a very little commuting, E engine, no issues ever.
Some cars that blew up were not tracked much or at all, and it's impossible to spend any meaningful time near read line on public roads without going to jail or dying. So it's not high-revs that's killing these engines.
I cannot tell if this wear is from stress or abrasion, but typically in machines, lower speed causes abrasion wear (easier to break oil film at lower speed) and higher speed causes stress wear (forces are square of speed). This does look more like abrasion to me, but it can be that stress first breaks the coating and then the rest is done by abrasion - who knows.
I know of at least two other F-engine cars that track more than I do and drive as hard.
I'll report when mine blows up.
By the way, shifting manually, unless you are short-shifting really low, may be worse for the engine because
1) automatic will never bounce against the red line, and the engine spends milliseconds there per shift, and it does not redline in all gears either. When shifting manually, just one delayed shift with bounce of the red line can cause more time at peak revs than hundreds of automatic shifts.
2) when downshifting, automatic seems to figure out the latest moment it can downshift, sometimes even after turn entry, thus keeping engine at lower revs. When shifting manually, drivers tend to try to get done with downshifting earlier, thus resulting in higher revs.
But that's a moot point.
Some cars that blew up were not tracked much or at all, and it's impossible to spend any meaningful time near read line on public roads without going to jail or dying. So it's not high-revs that's killing these engines.
I cannot tell if this wear is from stress or abrasion, but typically in machines, lower speed causes abrasion wear (easier to break oil film at lower speed) and higher speed causes stress wear (forces are square of speed). This does look more like abrasion to me, but it can be that stress first breaks the coating and then the rest is done by abrasion - who knows.
I know of at least two other F-engine cars that track more than I do and drive as hard.
I'll report when mine blows up.
By the way, shifting manually, unless you are short-shifting really low, may be worse for the engine because
1) automatic will never bounce against the red line, and the engine spends milliseconds there per shift, and it does not redline in all gears either. When shifting manually, just one delayed shift with bounce of the red line can cause more time at peak revs than hundreds of automatic shifts.
2) when downshifting, automatic seems to figure out the latest moment it can downshift, sometimes even after turn entry, thus keeping engine at lower revs. When shifting manually, drivers tend to try to get done with downshifting earlier, thus resulting in higher revs.
But that's a moot point.
11-28-2016, 10:45 PM
#260
Burning Brakes
Dry sump oiling solves the pressure issue on the low end, it would be a distribution issue up top if that were an issue but it seems the race cars have disproven that theory.
11-28-2016, 11:10 PM
#261
Almost always Auto on track, 17K miles total, probably about 3K on track and the rest is driving to track on a highway and a very little commuting, E engine, no issues ever.
Some cars that blew up were not tracked much or at all, and it's impossible to spend any meaningful time near read line on public roads without going to jail or dying. So it's not high-revs that's killing these engines.
I cannot tell if this wear is from stress or abrasion, but typically in machines, lower speed causes abrasion wear (easier to break oil film at lower speed) and higher speed causes stress wear (forces are square of speed). This does look more like abrasion to me, but it can be that stress first breaks the coating and then the rest is done by abrasion - who knows.
I know of at least two other F-engine cars that track more than I do and drive as hard.
I'll report when mine blows up.
By the way, shifting manually, unless you are short-shifting really low, may be worse for the engine because
1) automatic will never bounce against the red line, and the engine spends milliseconds there per shift, and it does not redline in all gears either. When shifting manually, just one delayed shift with bounce of the red line can cause more time at peak revs than hundreds of automatic shifts.
2) when downshifting, automatic seems to figure out the latest moment it can downshift, sometimes even after turn entry, thus keeping engine at lower revs. When shifting manually, drivers tend to try to get done with downshifting earlier, thus resulting in higher revs.
But that's a moot point.
Some cars that blew up were not tracked much or at all, and it's impossible to spend any meaningful time near read line on public roads without going to jail or dying. So it's not high-revs that's killing these engines.
I cannot tell if this wear is from stress or abrasion, but typically in machines, lower speed causes abrasion wear (easier to break oil film at lower speed) and higher speed causes stress wear (forces are square of speed). This does look more like abrasion to me, but it can be that stress first breaks the coating and then the rest is done by abrasion - who knows.
I know of at least two other F-engine cars that track more than I do and drive as hard.
I'll report when mine blows up.
By the way, shifting manually, unless you are short-shifting really low, may be worse for the engine because
1) automatic will never bounce against the red line, and the engine spends milliseconds there per shift, and it does not redline in all gears either. When shifting manually, just one delayed shift with bounce of the red line can cause more time at peak revs than hundreds of automatic shifts.
2) when downshifting, automatic seems to figure out the latest moment it can downshift, sometimes even after turn entry, thus keeping engine at lower revs. When shifting manually, drivers tend to try to get done with downshifting earlier, thus resulting in higher revs.
But that's a moot point.
Just comes down to luck I guess.
11-28-2016, 11:17 PM
#262
Nordschleife Master
11-29-2016, 02:26 AM
#263
RL Community Team
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11-29-2016, 09:37 AM
#264
Originally Posted by Waxer
No, it comes down to it shouldn't happen. Period.
I have high expectations on gen 2 991gt3. I think it will be very reliable.
Once again hope OP gets his gt3 sooner rather than later.
11-29-2016, 10:55 AM
#265
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posted in wrong thread. sorry. deleted.
__________________
PCA National Instructor
TPC Racing stats:
2023 Porsche Sprint Challenge 992 Cup Am Champion
2023 Porsche Sprint Challenge GT4 Pro-Am Team Champion
2022 Porsche Sprint Challenge 992 Cup & 991 Cup Champion
2020 IMSA GT3 Cup Challenge 2nd Championship
2018 IMSA GT3 Cup Challenge 2nd Championship
2016 IMSA GT3 Cup Challenge Champion
2013 IMSA GT3 Cup Challenge Champion
2006 Rolex-24 @ Daytona GT Champion
2004 Grand-Am SGS Class Champion
PCA National Instructor
TPC Racing stats:
2023 Porsche Sprint Challenge 992 Cup Am Champion
2023 Porsche Sprint Challenge GT4 Pro-Am Team Champion
2022 Porsche Sprint Challenge 992 Cup & 991 Cup Champion
2020 IMSA GT3 Cup Challenge 2nd Championship
2018 IMSA GT3 Cup Challenge 2nd Championship
2016 IMSA GT3 Cup Challenge Champion
2013 IMSA GT3 Cup Challenge Champion
2006 Rolex-24 @ Daytona GT Champion
2004 Grand-Am SGS Class Champion
Last edited by Tom@TPC Racing; 11-29-2016 at 10:56 AM. Reason: posted in wrong thread
11-29-2016, 11:15 AM
#266
Rennlist Member
I'm watching and I too have hopes, but they're not there yet. With every new solution iteration that fails, the latest Mezger GT3/RS go higher in price as folks that may want to upgrade to a newer GT are reluctant to venture beyond 997.2. This trend will become even more pronounced as the 991's go out of warranty.
11-30-2016, 07:41 PM
#268
Rennlist Member
I could be really wrong here, so any input/correction is welcome. Cyl 6 is on the outside of cars traveling counterclockwise. Which is the case at Daytona for the most part of the combined bank/inner loop. I would expect oil to be pushed in that direction even with a dry sump system. Seems to be counterintuitive to have an oiling issue that way. Yet of those that have reported engine problems cyls 5&6 seem to be the problematic ones. Any reason for that? Design issue?
This is why I posted earlier to see if we could get data on which cars reporting issues are tracked clockwise v. Counter and which cylinders are coming up short. Maybe this could shed light on our problem. Maybe we can get enough data to eliminate this variable out of the mix or maybe it does show some correlation.
This is why I posted earlier to see if we could get data on which cars reporting issues are tracked clockwise v. Counter and which cylinders are coming up short. Maybe this could shed light on our problem. Maybe we can get enough data to eliminate this variable out of the mix or maybe it does show some correlation.
I thought it was just my imagination but i felt like Daytona didn't generate the high lateral Gs. Yes the banking creates a constant push to the wall that you counter with some steering but that is small and most of the force is down into the pavement. At least that's the way it felt to me. I checked the G meter and Daytona only generated 1.3-1.36 peak Gs, albeit for a sustained period. I see much higher peak readings from Sebring of 1.49-1.52. Agree Sebring is probably shorter duration but those Daytona numbers don't seem that high for oil starvation.
Wish I knew what caused this. Hopefully Porsche knows...
12-01-2016, 12:02 PM
#269
Rennlist Member
Thread Starter
Talked to PCNA this morning. They are going to repair the car and put a new engine in it. We're still working through a few details, but I wanted to share the general news that they are accepting ownership of the issue.
12-01-2016, 12:18 PM
#270
Originally Posted by rm21
Talked to PCNA this morning. They are going to repair the car and put a new engine in it. We're still working through a few details, but I wanted to share the general news that they are accepting ownership of the issue.
