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992 chassis: Is it all new? Engine moved toward the middle? Torsional rigidity?

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992 chassis: Is it all new? Engine moved toward the middle? Torsional rigidity?

Old 11-29-2018, 05:51 AM
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K-A
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Default 992 chassis: Is it all new? Engine moved toward the middle? Torsional rigidity?

What we (I) do know is that contrary to previous belief, the wheelbase is identical. Therefore the extra length is all in the front overhang. The 992, also contrary to what was previously reported, is .2" higher than the 991.2 (maybe the larger rear wheels have to do with that). It's also about 150 lbs heavier than the 991.2, making it about 250 lbs heavier than the 991.1.

C&D reported that the structure under the skin is similar to the 991. Which starts to lead me to believe it is the same chassis.

Two things that can help answer that: Has Porsche released torsional rigidity figures, and if so, what are they (the 991 is around 40K nm)? Although, even with increased rigidity figures, it can be the same chassis. Still curious to know the rigidity compared to the 991 (e.g: the 991 is 25% stiffer than the 997).

Also, I still haven't seen anything about the engine moving more towards the middle again. This was a big talking point during the testing phase, as it was nearly bond that it was moving further forward. Now, not so sure.
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Old 11-29-2018, 08:54 AM
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Also the rear was set to have space for the hybrid ie batteries
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Old 11-29-2018, 06:11 PM
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From the first spy photos it has been quite clearly an evolution of the 991, not an all-new car. 964>993, 996>997, 991>992...
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Old 11-29-2018, 06:35 PM
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As somebody else stated its virtually a 991.3. Its an evolution of the existing 991.2 car. Its not a new platform.

However, while the engine is in the same place, they have significantly changed how and where is it mounted in order to improve the overall stiffness of the chassis.
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Old 11-29-2018, 07:08 PM
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Disappointed...
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Old 11-30-2018, 07:49 AM
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Originally Posted by Alan Smithee View Post
From the first spy photos it has been quite clearly an evolution of the 991, not an all-new car. 964>993, 996>997, 991>992...
Good and concise way to put it. And spot on.

Originally Posted by Chris3963 View Post
As somebody else stated its virtually a 991.3. Its an evolution of the existing 991.2 car. Its not a new platform.

However, while the engine is in the same place, they have significantly changed how and where is it mounted in order to improve the overall stiffness of the chassis.
Interesting. Any links on them going into detail on said placement and stiffness? And has anyone stated how much stiffer the 992 is (percentage or otherwise)?
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Old 11-30-2018, 03:03 PM
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Originally Posted by K-A View Post
Good and concise way to put it. And spot on.



Interesting. Any links on them going into detail on said placement and stiffness? And has anyone stated how much stiffer the 992 is (percentage or otherwise)?
I looked around the 992 at the LA Autoshow yesterday. From what I can tell, no change to location of the engine judging by the distance of the oil pan to the rear cross member. If it was shifted at all, can't be more than 10mm. However, there was no visibility to engine mount locations and whatnot, so it's quite possible those were moved around.
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Old 11-30-2018, 05:08 PM
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According to Road and Track: Porsche also moved the engine mounts 20mm further forward in the chassis, increasing rigidity and shifting the weight balance a little bit.

https://www.google.com/amp/s/www.roa...specs-details/
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Old 11-30-2018, 08:01 PM
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Originally Posted by Ccpecot View Post
According to Road and Track: Porsche also moved the engine mounts 20mm further forward in the chassis, increasing rigidity and shifting the weight balance a little bit.

https://www.google.com/amp/s/www.roa...specs-details/
I'm guessing just the engine mounts were moved. Those mounts are located nearly all the way at the back of the car, so moving them forward a bit helps with the balance and rigidity. Makes sense.
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Old 12-15-2018, 01:55 AM
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Originally Posted by K-A View Post
Interesting. Any links on them going into detail on said placement and stiffness? And has anyone stated how much stiffer the 992 is (percentage or otherwise)?
R&T claims the 992 is 5% stiffer than outgoing 991.2. (click for source)

R&T specifies the 991.2 rather than saying 991; are they are implying a 991.2 is stiffer than a comparable 991? I don't know.

Anyway, the 991 is supposedly 40,000 NM per degree.

Originally Posted by jumper5836 View Post
991 40k nm/deg
5% increase would place the 992 at 42,000 NM/deg.

The same R&T article also says the engine mounts (says nothing about engine centerline) have moved forward a not-really-believable 6.6" (168mm), rather than the 20mm previously quoted.

Originally Posted by Road & Track
To better control the movement of the flat-six hanging behind the rear wheels, the 992 moves the engine mounts forward 6.6 inches. (click for source)
Originally Posted by Road & Track
Porsche also moved the engine mounts 20mm further forward in the chassis, increasing rigidity and shifting the weight balance a little bit forward. (click for source)
While everything is relative, I would not say the 992 is just a "991.3." The chassis is entirely different and reengineered. Things changed include the wheelbase, suspension geometry, engine placement, track width, etc. Engineered from the ground up? No, but nothing ever is.

Anyway, the 992 chassis uses around 60% aluminum, 991 was around 30%. That statistic alone is evidence the chassis would have to be comprehensively reevaluated for stiffness, deflection, handling, crashworthiness, corrosion resistance, fatigue, etc.

Last edited by FrenchToast; 12-15-2018 at 02:39 AM.
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Old 12-15-2018, 03:06 AM
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The 992 use the new MMB platform





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Old 12-15-2018, 04:38 AM
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The engine mounts are 20cm further forward according to the marketing document supplied to dealers.
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Old 12-15-2018, 06:06 AM
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So there will be a GT3 Cab.
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Old 12-15-2018, 09:49 AM
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Originally Posted by pietrostone View Post
The 992 use the new MMB platform





Platform MMB that will be used for the next 718
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Old 12-15-2018, 11:50 AM
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When the 991.1 came out it was the perfect 911. Until the 991.2 arrived. With the 992 and such a change as moving the engine mounts forward... why the he didnít someone think of that in 2012? Seems like such a basic, common sense engineering component.

Btw, since itís the same chassis... thatís a testimony to just how good the 991.1 chassis is! With the likes of carbon fiber and monocoque coming down market, no way Porsche would release a new 911 that wasnít competitive.
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