Gt4 awesome at COTA but sad ending :(
07-18-2016, 01:10 PM
#136
Drifting
It would have been a nice track if the surface at Harris Hill has not become atrocious with horrible bumps and no real fixes in sight. After torn engine mounts on my M3 and now two incidents of bent wheels on my GT4 (never going off...)I am unfortunately canceling my membership. 
07-18-2016, 02:14 PM
#137
It's more an indictment of the horrendous bumps on the track now and me being really good at breaking things ;-) than the oem wheels.
It also not two GT4 wheels, but one oem wheel and one high end forged wheel. Both were not bent in "incidents" where you are immediately aware of, but were found out when rebalanced after track events due to vibrations. So, even the forged wheel bent. This wheel is at the manufacturer for inspection and hopefully will be replaced under warranty as there is no way it should have bent, even if the surface was as bad as it is.
I think the oem wheels are fine, the problem is that if something DO happen they are ridiculously expensive. The more I think about it, I should have just gotten the OZ setup very early and treated then like consumables. I can get almost a complete set for the price of one oem wheel.
07-18-2016, 02:25 PM
#138
Racer
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Long story, so in trying to not take thread completely off topic and turn into wheel debate, here's the short version.
It's more an indictment of the horrendous bumps on the track now and me being really good at breaking things ;-) than the oem wheels.
It also not two GT4 wheels, but one oem wheel and one high end forged wheel. Both were not bent in "incidents" where you are immediately aware of, but were found out when rebalanced after track events due to vibrations. So, even the forged wheel bent. This wheel is at the manufacturer for inspection and hopefully will be replaced under warranty as there is no way it should have bent, even if the surface was as bad as it is.
I think the oem wheels are fine, the problem is that if something DO happen they are ridiculously expensive. The more I think about it, I should have just gotten the OZ setup very early and treated then like consumables. I can get almost a complete set for the price of one oem wheel.
It's more an indictment of the horrendous bumps on the track now and me being really good at breaking things ;-) than the oem wheels.
It also not two GT4 wheels, but one oem wheel and one high end forged wheel. Both were not bent in "incidents" where you are immediately aware of, but were found out when rebalanced after track events due to vibrations. So, even the forged wheel bent. This wheel is at the manufacturer for inspection and hopefully will be replaced under warranty as there is no way it should have bent, even if the surface was as bad as it is.
I think the oem wheels are fine, the problem is that if something DO happen they are ridiculously expensive. The more I think about it, I should have just gotten the OZ setup very early and treated then like consumables. I can get almost a complete set for the price of one oem wheel.
07-18-2016, 02:54 PM
#139
FWIW, for the price I like the OZ, but the only drawback is that my shop is having trouble getting the optimal track alignment due to the offsets (i.e. they can't lower the car as much as they would like to b/c of rubbing, etc.) This is unfortunately causing the rear end to "wiggle" under hard breaking (ex. turn 12 @ COTA). Haven't decided if I really want to spend ~5k on forgelines to get the optimal offsets.
T12@cota is also pretty much as hard as you'll ever brake and your braking technique can contribute. This car can brake like crazy, but does NOT like being stood on it's nose in general
07-18-2016, 04:53 PM
#141
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I've tried several breaking "techniques" and they all cause the tail to move to some extent with some more than others.
Hmm I need to try this by increasing pressures. I'm currently at 35r/34f hot.
07-19-2016, 02:51 PM
#142
Former Vendor
True T12 is a BEAST. Lol...sat there for 2 COTA F1 races
Has annihilated many a brake setup from my numerous TX customers...some YIPES! type stories there......
Has annihilated many a brake setup from my numerous TX customers...some YIPES! type stories there......
07-19-2016, 03:48 PM
#143
Rennlist Member
Jslee225 - any update on repairs? I assume they finally got some undamaged cylinder heads.
http://youtu.be/l5KmxPMtSwY
Car was doing awesome all weekend even pulled double duty running 2 run groups by giving people rides. Not sure what happened but if you skip to 10 min you'll hear a loud fast buzzing noise appear around 7k right before I'm about to short shift to 3rd (i.e. did not shift). Then it was error code city! Found out later that some of the codes were camshaft and multiple cylinder misfire.
Good thing I was near the pits. Parked the car and shut it down and the car wouldn't start back up. Had car towed to dealer. I won't be able to sleep tonight
Any ideas what happened?
Car was doing awesome all weekend even pulled double duty running 2 run groups by giving people rides. Not sure what happened but if you skip to 10 min you'll hear a loud fast buzzing noise appear around 7k right before I'm about to short shift to 3rd (i.e. did not shift). Then it was error code city! Found out later that some of the codes were camshaft and multiple cylinder misfire.
Good thing I was near the pits. Parked the car and shut it down and the car wouldn't start back up. Had car towed to dealer. I won't be able to sleep tonight
Any ideas what happened?
07-19-2016, 04:38 PM
#144
For those who know, any correlation between GT3 (mostly E and F engines) and GT4 engine failures? And most importantly, can any 3.4L engines be affected by that? GT3s also have oiling and DLC issues, but I'm asking about the cam issues present in both, although G (2016) GT3 engines apparently were fixed. And all GT4s are 2016, so not sure it's the same issue. I ask because all 991/981 engines supposedly belong to the same 9A1 family, so all could have the same issue, especially if tracked. After the GT3 fiasco in 2014, I couldn't believe so many 2015 engines were failing. Doesn't Porsche test engines anymore? Just hope my 2016 3.4L is not affected by that. And even though I won't track that car (no worries), I'd still like to know. Thx.
07-19-2016, 04:46 PM
#145
Three Wheelin'
For those who know, any correlation between GT3 (mostly E and F engines) and GT4 engine failures? And most importantly, can any 3.4L engines be affected by that? GT3s also have oiling and DLC issues, but I'm asking about the cam issues present in both, although G (2016) GT3 engines apparently were fixed. And all GT4s are 2016, so not sure it's the same issue. I ask because all 991/981 engines supposedly belong to the same 9A1 family, so all could have the same issue, especially if tracked. After the GT3 fiasco in 2014, I couldn't believe so many 2015 engines were failing. Doesn't Porsche test engines anymore? Just hope my 2016 3.4L is not affected by that. And even though I won't track that car (no worries), I'd still like to know. Thx.
07-19-2016, 07:31 PM
#146
For those who know, any correlation between GT3 (mostly E and F engines) and GT4 engine failures? And most importantly, can any 3.4L engines be affected by that? GT3s also have oiling and DLC issues, but I'm asking about the cam issues present in both, although G (2016) GT3 engines apparently were fixed. And all GT4s are 2016, so not sure it's the same issue. I ask because all 991/981 engines supposedly belong to the same 9A1 family, so all could have the same issue, especially if tracked. After the GT3 fiasco in 2014, I couldn't believe so many 2015 engines were failing. Doesn't Porsche test engines anymore? Just hope my 2016 3.4L is not affected by that. And even though I won't track that car (no worries), I'd still like to know. Thx.
The current GT3 issues with the 2014 E and 2015 F motors seems to be insufficient oil supply to the heads resulting in cam/ follower wear. Although maybe some problems with coatings too? The 2 GT4 failures I've heard of were the bolts attaching the Variocam cam gear. Not sure the root cause but sounds like much different issues.
07-19-2016, 07:36 PM
#147
For those who know, any correlation between GT3 (mostly E and F engines) and GT4 engine failures? And most importantly, can any 3.4L engines be affected by that? GT3s also have oiling and DLC issues, but I'm asking about the cam issues present in both, although G (2016) GT3 engines apparently were fixed. And all GT4s are 2016, so not sure it's the same issue. I ask because all 991/981 engines supposedly belong to the same 9A1 family, so all could have the same issue, especially if tracked. After the GT3 fiasco in 2014, I couldn't believe so many 2015 engines were failing. Doesn't Porsche test engines anymore? Just hope my 2016 3.4L is not affected by that. And even though I won't track that car (no worries), I'd still like to know. Thx.
9A1 engines (introduced in 2009) have generally been bulletproof even with extensive track usage. Yes, some 991 GT3 engines failed but that's a different engine. 9A1-based but different. Besides, underneath all the hysteria only few GT3 engines actually failed.
Last edited by the_vetman; 07-26-2016 at 07:48 PM.
07-20-2016, 02:43 PM
#148
... and probably just a manufacturing defect (built on a Friday. He he). Thank you very much for all the responses, and the explanation of differences among 9A1 engines. Much appreciated. Good to hear there's nothing to worry about with 3.4L engines. But there're more than 'a few' GT3 engine failures; just read the 60+ page thread about that over the 991 GT3 section, if in doubt
. But as mentioned, that was mostly for oiling issues wearing followers. And on that note, I thought our DOHC engines didn't have any followers/rockers, especially since GT3 engines have a 9K-rpm limit. What happened to cams actuating directly over the valves (via buckets)? That design could be part of the problem, but the good news is our 7,800-rpm engines are not affected. Have a great afternoon gang.
07-20-2016, 02:51 PM
#149
It's been covered multiple times in this thread - NO.
9A1 engines (introduced in 2009) have generally been bulletproof even with extensive track usage. Yes, some 991 GT3 engines failed but that's a different engine. 9A1-based but different. Besides, underneath all the hysteria only few GT3 engines actually failed.
9A1 engines (introduced in 2009) have generally been bulletproof even with extensive track usage. Yes, some 991 GT3 engines failed but that's a different engine. 9A1-based but different. Besides, underneath all the hysteria only few GT3 engines actually failed.
per the engine in the GT4, there have been more miles put on the design, but it is by no means bulletproof either - though it seems more of an assembly quality issue than design issue (like the GT3 suffers from).
07-21-2016, 12:03 AM
#150
Drifting
On the Cup 2s I've been shooting for 36 hot all around according to TPMS, which usually puts me around 35 hot according to my gauge immediately after the cooldown half-lap. I find it makes for a good feel all session. The tires can actually take quite a while to come up to that pressure, but they feel good all the way to that point. Every time the car has started to feel loose all of a sudden out there, I've glanced down and seen at least one 38 on my TPMS readout in the rear, often from not proactively taking a bit of air out between morning and afternoon sessions to account for afternoon temperatures.