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@ilko Thanks for posting this. It seems problem with yours and Elliots is the shaft broke and not screws backing out. Looks like the shaft fails where the plate mounts due to fatigue. Not sure if its tolerance as AP mentions or material selection/size/design, in the sales literature it describes the valves operate off of 'vibration'. I am curious what is done to the revised versions, not sure but it looks like you can see more machining marks on the new shaft where the screws are vs the old?
Seems like it can be improved by the aftermarket if someone puts effort into it. 1144 stress proof steel might be a viable option for replacement shafts. 1144 stress proof steel description
The first step would be to send one of the failed shafts out for composition testing to find out the material that failed.
@RAudi Driver here are some pics of the dundon version, definitely looks like you will be sacrificing low end with no flaps, just a large cavity and a bbk hellcat throttle body.
Here are some pictures from my engine, taken a couple of years ago. The motor had 35K miles at the time of the failure...
Here is a photo of the part number of the manifold that failed, it was installed during the recall in 2013. Part number 997 110 116 91, dated 2013. The newest/current version of this center manifold is 997 110 116 95.
I posted my solution in the other thread, we installed screens on each end of that chamber, to catch any shrapnel, if the arm ever brakes again. Here it is one more time:
Finally... Andreas Preuninger and his team are well aware of this problem. He admits it in an interview with 000 from a few years ago:
@ilko thanks for sharing all of this. it is very helpful. I just ordered part number 997 110 116 95, and It showed up with the part number on the casting as 997 110 116 91 with the written number 2603. See the photo in my previous post. The AP post suggests the issue is actually with the hole for the shaft. Its diameter is incorrect, causing extra wear on the rod itself. It looks like even the plastic plenum has issues, but it is not nearly as deadly.
Originally Posted by bonehead
@Elliotw44 aw man. Just catching up with all this. Really sorry to see this.
All this time, the talk has been about failed screws getting sucked into the intake when it's actually been the shaft itself that's the weak point. Not that it makes a difference as far as someone blowing up their motor, but the solution unfortunately isn't as simple as tack welding as @powdrhound suggested.
So is it my understanding that those that have had these failures already had the updated part number installed?
My car had the updated piece installed in 08/2013. It is unclear if there have been further revisions(beyond 2013). I have seen the following part numbers in reference to the center plenum: 997 110 116 90,997 110 116 91, 997 110 116 93, 997 110 116 95. This creates a lot of confusion and I don't fully understand which part is most updated and goes with what trim.
Ilko thanks for sharing all of this. it is very helpful. I just ordered part number 997 110 116 95, and It showed up with the part number on the casting as 997 110 116 91 with the written number 2603. See the photo in my previous post. The AP post suggests the issue is actually with the hole for the shaft. Its diameter is incorrect, causing extra wear on the rod itself. It looks like even the plastic plenum has issues, but it is not nearly as deadly.
My car had the updated piece installed in 08/2013. It is unclear if there have been further revisions(beyond 2013). I have seen the following part numbers in reference to the center plenum: 997 110 116 90,997 110 116 91, 997 110 116 93, 997 110 116 95. This creates a lot of confusion and I don't fully understand which part is most updated and goes with what trim.
Very good info in this thread, thanks to all for contributing!
It seems that all of the failures posted above had P/N 997-110-116-91 followed by some number hand etched/engraved...
Has anyone received or seen a plenum with the latest P/N ending -95?
Very good info in this thread, thanks to all for contributing!
It seems that all of the failures posted above had P/N 997-110-116-91 followed by some number hand etched/engraved...
Has anyone received or seen a plenum with the latest P/N ending -95?
I believe my shop ordered the P/N ending in -95 but received the part below. Which is why I am confused.
Originally Posted by Elliotw44
I am planning on doing a full teardown of the broken part. But that is going to be a while.
The 997.110.116.95 part arrived, and its part number on the casting actually ends in 91 with the written number 2603. The manufacturer is still MWK. Photos:
The 7.1 3.6 and 7.2 GT3 originally had the .90 part. The 7.2 RS and 4.0 RS had the .91 part. Both the .90 and .91 appear to have been updated to .93 and then .95. It appears there is only one version for all the cars now which is the .95. With that said, the revisions don't necessarily mean it's a new or improved part. It may be a redesigned part but usually it's not. The revision parts are normally implemented when Porsche implements a price increase. In many cases the old part number is still present with the new number added to the packing material. Sometimes the new part number sticker is simply placed over the old revision number.
So, I pulled my spare 2011 997.2Cup manifold from my parts bin. According to PET this is supposed to be the same part as the street car 3.6 and 3.8 non-RS part (997.110.116.90). Interestingly, looking at the part number that is cast into the resonance manifold, it reads 997.110.216.9R. The R typically designates a motorsport part in many cases. I has a 12/2010 date of manufacture. I am going to take this to the shop and have it taken apart there and looked at closer. I will also look at the 2016 991Cup motor I have there and see what number is on that manifold although PET also shows it as a 997.110.116.90 part.
If anyone could measure the I.D of the resonance tubes on their .91 and .95 intake I would be curious to know what that is. I can compare it to the Cup one. Perhaps the larger resonance tubes in the .91 part made the stress on the rod worse resulting in the failures?? I am not aware of any .90 manifolds having failures and maybe that is why Porsche Motorsport decided to use those even though the designation on those is a 216.9R and not 116.90 as per PET.
Last edited by powdrhound; 05-26-2024 at 12:51 PM.
I'd like to point out that you guys are reading the part number off the casting.
When you purchase the part you get the casting and all the resonance flap mechanisms.
Porsche never would have had reason to change the casting, at least in an attempt to fix this particular problem. The shaft for the throttle valve is the problem, and that shaft does not have its own part number, so it is impossible to know about redesigns or revisions.
I think AP's explanation shown above is complete bull****. It shifts blame to the supplier, away from Porsche's engineering dept. Also, aluminum plenums came back some time after the 991.1 GT3. I have a 2020 GT4 engine in the shop. It has an aluminum plenum that is very similar to what we are talking about here.
Ilko's excellent pictures show that the shaft has failed comprehensively from fatigue. Every possible stress raiser has been hammered into fatigue failure. I suspect the 3.8 and especially the 4.0 engine makes intake pulses strong enough to be above the fatigue limit of the (probably excellent quality) steel shaft. The 3.6 engine did not do this, and the part was never redesigned until it began to fail in service.
Moral of the story, get a GT3 that has the proven 3.6 liter engine and you won’t have this issue or the cam actuator bolts backing out. Just kidding but just a thought. Good Thread.
Plastic also can deal with vibrations a lot better than cast aluminum. The Dundon part is ridiculously expensive, but compared to a Mezger rebuild, it's a lot cheaper. I bought one for long-term safety. My car has 33k miles and is still used at the track as it was intended to be, can't but feel my number will come up eventually too.
A little low-end power loss doesn't bother me one bit, especially with the peace of mind and huge mid-upper end range bump it provides. Between this and the ATI damper already installed, should make the 3.8 reliable for many years to come.
I'll post about the install process and if it is "really" able to be installed with the engine in the car. They say it is because of the multi-piece design, but we'll see.
Plastic also can deal with vibrations a lot better than cast aluminum. The Dundon part is ridiculously expensive, but compared to a Mezger rebuild, it's a lot cheaper. I bought one for long-term safety. My car has 33k miles and is still used at the track as it was intended to be, can't but feel my number will come up eventually too.
A little low-end power loss doesn't bother me one bit, especially with the peace of mind and huge mid-upper end range bump it provides. Between this and the ATI damper already installed, should make the 3.8 reliable for many years to come.
I'll post about the install process and if it is "really" able to be installed with the engine in the car. They say it is because of the multi-piece design, but we'll see.
damn beat me to it, I bet they only have like 2 in stock.
yes please… i remember going through process and reading about how to do it without removing the engine… but I still think it wants a 2-3 inch engine drop?
The 7.1 3.6 and 7.2 GT3 originally had the .90 part. The 7.2 RS and 4.0 RS had the .91 part. Both the .90 and .91 appear to have been updated to .93 and then .95. It appears there is only one version for all the cars now which is the .95. With that said, the revisions don't necessarily mean it's a new or improved part. It may be a redesigned part but usually it's not. The revision parts are normally implemented when Porsche implements a price increase. In many cases the old part number is still present with the new number added to the packing material. Sometimes the new part number sticker is simply placed over the old revision number.
Is there a difference between 7.2 GT3 and 7.2 GT3RS plenums since the part numbers have merged? Has there been any reported cases of flaps disintegrating on a GT3 non-RS? Thanks.
Is there a difference between 7.2 GT3 and 7.2 GT3RS plenums since the part numbers have merged? Has there been any reported cases of flaps disintegrating on a GT3 non-RS? Thanks.
The 7.1 and 7.2 NON RS use the .90 plenum with the smaller resonance tube. The 7.2RS and 4.0 use the .91 with the larger tube which had the failures. I'm guessing that Porsche went to the smaller resonance tube on the .95 revision which now covers both cars. It appears that the larger resonance tube increases the vibration to the point of metal fatigue / failure much more so than the smaller one. If someone can measure the ID of the resonance tubes on the .95 plenum I can compare it to the .90 one I have at the shop to test the theory..
I would speculate that as the 7.2RS cars accumulate more mileage we will see more failures. Anyone know what the highest mileage .2RS is?
The 7.1 and 7.2 NON RS use the .90 plenum with the smaller resonance tube. The 7.2RS and 4.0 use the .91 with the larger tube which had the failures. I'm guessing that Porsche went to the smaller resonance tube on the .95 revision which now covers both cars. It appears that the larger resonance tube increases the vibration to the point of metal fatigue / failure much more so than the smaller one. If someone can measure the ID of the resonance tubes on the .95 plenum I can compare it to the .90 one I have at the shop to test the theory..
I would speculate that as the 7.2RS cars accumulate more mileage we will see more failures. Anyone know what the highest mileage .2RS is?
@Steve Theodore is up there in miles for a
7.2 RS. Steve, can you chime in with your current mileage?
05-25-2024, 07:21 PM
