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Hello all, I am considering adding headers to my 997.1S. I currently have Cargraphic mufflers & Cargraphic 200 cell X-pipe in addition to the APR software, IPD Plenium, GT3 throttle body, Fabspeed duel Intake . People w/ headers what can I expect from adding these to my car. Will there be any performance gains or sound? I added the intake & cats earlier this year & I was so impressed w/ the 200 cell cats.
Because you have the other intake and exhaust mods, I think the headers will complete the package and improve exhaust gas egress which may show some additional benefits at higher rpms. Make sure you get equal length headers that flow into a properly designed merged collector The problem with the stock headers is that the exhaust from each cylinder exits along a line to an essentially straight pipe and doesn't flow all that well due to turbulence created in the collector.
I'm running the X-51 headers on my car, along with new intake, plenum and ICU flash. All seems to work well in concert. Simply comparing the X-51 headers to the stock headers is quite illuminating - the stock headers are small and restrictive - X-51 noticeably larger and seemingly better engineered for performance.
Here are some pics. First pic compares a stock header (left) with the X51 Header (right). See how the flow from each input on the stock header would tend to collide where they meet in the collector coming in from different angles vs. the X51 header where all the flow is essentially in the same direction.
The next step up is a setup like Fabspeed, FVD, Sharkwerks, etc where the 3 pipes are all the same length, which balances the gas egress from the cylinders, and all arrive into the merging collector on the same angle vs. the X51 where pipes are different lengths and the input angles to the merging collector are also different. Since the motor has a firing sequence, header pipes of the same length mean the exhaust pulse through one pipe on a side takes the same length of time as either of the others on that same side so header pipes of the same length create sequenced pulses in a continuous stream without colliding with one another. When the header pipes are of different length, some of the pulses collide at the collector which creates turbulence and more of a wave shape that goes up and down when pulses superimpose on one-another, instead of a more continuous, linear, and efficient exit of the pulse stream.
Going with a cross-cat or X-cat setup also helps balance the draw and flow from both sides of the engine since they're connected at the X junction in the middle.
Is the dyno chart above showing gain from the Fabspeed headers alone or is there additional aftermarket components over a stock 997S ?
+27lb-ft of torque and +20hp @ 4000 rpm is remarkable gain for a pair of headers
Petza914's post showed how the exhaust gases had to fight each other to get through the stock merge collector, its a huge bottleneck. Eliminating the bottleneck allows for optimal performance gains.
The dyno I posted is a stock Carrera S vs. Carrera S with our Sport Headers that is otherwise stock.
The Dyno chart is particularly telling. Look at the transition point that occurs at 3,500 rpm. This is where the Variocam + kicks in and the engine changes the intake cam timing for both higher lift and longer duration, meaning more fuel into the motor. The stock headers can't expel the spent gasses from his increase nearly as effectively as the Fsbspeed headers, and why the distinct difference in the chart starting at that point. If you can get even more air (which also means more fuel - providing you don't exceed the fuel delivery capability of your setup) into the motor, the difference between the two lines on the chart will become even greater. This is why a cold air intake by itself does very little to add HP, just some intake sound and improved throttle response, but when paired with exhaust mods and a tune can make a significant and noticeable difference.
..... exhaust gases had to fight each other to get through the stock merge collector, its a huge bottleneck......
I had thought/read that the OEM cat pipes were the biggest bottleneck in the 997.1S exhaust but this dyno chart seems to provide a different narrative to say otherwise ? No ?
I had thought/read that the OEM cat pipes were the biggest bottleneck in the 997.1S exhaust but this dyno chart seems to provide a different narrative to say otherwise ? No ?
Yes, stock cats are another restriction point compared to their 200 cell X-cats shown in my earlier post.
