mammothcar1

I've been researching the advantages/ disadvantages of aftermarket headers vs Porsche's 991.2 manifold design and came across this video.
They discuss the differences between the 991.2 9A2 engine and accessories vs the 992 9A2 Evo engine.

I was also struck at the complexity of the muffler in the cut away view.
Is the muffler on our 991.2 this complex?

Apologies if this was posted already.

VektorPerformance

There are some decent manifold pics floating around shoeing the differences. Essentially the 991.2 has a plenum-style exhaust manifold and the 992 has more of a log style. An improvement for sure, but not going to replicate the results of a well designed tubular header with a high velocity merge collect. Still room to grow

The cold side has some nice packaging improvements, but I'm surprised to see in that vid the downsides being highlighted.

mammothcar1

I was surprised about the downsides as well.

spdracerut

The exhaust manifold design on the 992, I first saw it on the gt2rs. So the updates are making its way down through the product line. It's a log manifold design as Vektor mentioned. It's better than the 991.2 design, but still no where as good as an equal length tubular design.

spdracerut

As for pushing the peak torque back a couple hundred rpm on the 992 vs 991.2. well, that peak torque rpm number is achieved on an engine dyno and would never be replicated in the real world. Unless you start a pull from 1000rpm in 6th gear.

That peak torque at low rpm is an indicator of lag and responsiveness that the driver feels. It's the easiest way to convey how laggy a car will feel to your general customer. If you broke it down to more engineering defined metrics, it would be like: time to torque in second gear starting at 2000rpm. And then time to torque in third gear at 2k rpm. And 3k rpm. And then you've totally lost your general customer.

Lag, you can drive around by keeping the rpms higher. And for everyday cruising around in automatic mode, I'm guessing the transmission shifting program is quick enough to figure out if the driver is just cruising of needs to accelerate quickly. And the extra lag may have been engineered in to improve fuel economy numbers.

The other part of the equation is the transient response, getting on/off throttle. This is where the updated log manifold helps a bit compared to the pile of metal garbage on the 991.2. And with pdk, the turbo won't spin down between shifts, so no transient lag there. The new intercooler setup is much better too improving transient response.

So even with the bigger turbos and supposed later peak torque, I bet the 992 feels just as responsive because the headers and intercooler setup are better.