What do you expect people to say? They spent hundreds of $$$ on snake oil... It's like any placebo... Don’t expect many who got taken by false promises of magic HP gains to admit there was no real benefit after spending their hard earned money…

Remember… if it was SO easy as just adding this special plenum then don’t you think Porsche would have done it? I’d like to think that Porsche has the R&D budget to invest in such efforts….

Save your money…

Matt

 

Porsche would have also added a lot of other things too like a limited slip differential, full leather would be standard as well as a sport exhaust . The "S" wsoild have been the base model and it would come fully equipped standard --like Honda does--lol .

But that's dreamland . Reality is-- to get extra HP one has to alter the car with some parts and software.

I am facing my first plenum question but am not sure of it's a Turbo related issue or somehow ties into the massive breathing capacity of the Werks1 in combination with it .

Upon hard acceleration from third to forth I hear a "pssssss" sound when I let off the throttle. Like a mild blow off valve sound . After driving and when warn if I rev I can mimick the noise slightly.

The car is astoundly quick though and install looks clean so I'm not sure if my concern is actually normal for these parts combination.

 

Interesting points mentioned in the last two posts...

I too thought if the gains were that easy to get Porsche would have done it themselves and compared to full leather and LSD it would be much less costly for Porsche to add; but perhaps Porsche wants to keep a few of these little tricks up their sleeve for subsequent model year improvements/power gains...only they really know.

I will say this, if there is a legitimate 11.5 peak hp gain on a fully stock 997S then it is indeed worth it. I just don't like it when many aftermarket power upgrades for N/A cars advertise a 20+ hp increase when it's not for peak power which never comes close to those numbers and in some cases the peak power increase is nominal at best. The forced induction cars seem to get the best peak power increase bang for the buck when it comes to mods, as they generally and for the most part enhance the boost which can provide nice gains in hp and torque; something we used to do in the "old days" with a stiffer waste gate spring, we'd also always run with 104+ octane booster and richen up the mixture to keep any detonation at bay; this was all a very inexpensive and easy way to pick up nice gains in the 930's...my how times have changed.

 

What is the significance of peak horsepower? I should know this, but am afraid I don't fully understand.

 

When most discuss a car's horsepower or ask how much hp it has, peak or max hp is what's referred to. A 997S with 355 hp is its peak hp and if a mod quotes an increase of say 30 hp over stock most would think the power would go to 385 when in fact it may add 30 hp from say 200 to 230hp much lower in the power band which is not a bad thing at all, but it may not change the car's max/peak/total hp by 30 at all, and in many cases the cars peak gains are nominal. As I mentioned above turbo/forced induction cars for the most part are a different story and much easier to get peak as well as other increases by raising the boost amongst other things.

 

What surprised me is the OEM part clearly does not look ideal from a fluid dynamic standpoint. The RSS part does. If both pieces were in front of me and I didn't know which part was which, I would guess the RSS plenum was the one Porsche designed.

 

Some of the intake pieces on my former 06 E55 were the same way...too many of what appeared to be curves/twists/turns...but I guess AMG/MB knew what they were doing? Someone mentioned to me that straight-through is not always best as sometimes turbulence is needed.

 

Love your handle...the Foo Fighters are awesome!

 

Porsche has purposely reduced the power of the S engine with intake exhaust and ecu so they can sell an x51 kit.
This engine was designed to make 100bhp in the first place.
It makes perfect marketing sense to have product differentiation.
325bhp, 355, 381, 415 etc all going up in cost.
Just look at the exhaust manifold of the S, it doesn't take a genius to come to the conclusion that this is not a particularly free flowing design.
Are we saying, Porsche couldn't improve on this?
Simon

 

Add to that a throttle body straight off the 3.6 (same size) and it's clear Porsche definitely strangled the 'standard' 3.8 for marketing reasons. I agree with Simon that the original design for the 3.8 was what is now the X-51; nicely balanced design with no appreciable weak points (except the cats, but that's down to legislation). The design was simply too powerful to fit Porsche's marketing plans and was downgraded accordingly. Typical of what happens when bean-counters get to run an enthusiast car company.

Ian

 

this thread has def got my interest in replacing my original plenum to this upgraded one. Can anyone take a pick of the orig and the upgraded one side by side, and can anyone let me know if the upgrade requires or does not require a computer reset or any reset at all. Basically i just need to know if this is a simple upgrade or one which requires some computer work as well.
Any help would be great...gotta love this site, the collective knowledge is infinite.
Thanks in adavance,
Danny

 

It is a simple mod.Takes about 20mins.
Ian stated that doing a reset allowed his car to adapt to new changes faster.
I read that these motronics "pull away" from knock situations fast but adapt upwards quite slowly to avaoid damage.
You don't need to reset, it will just take longer to adapt.
Simon

 

Simon can u please explain what u meant by saying "these motronics...to avoid damage"?

 

It is funny that so many people fall for the logic that "if it could have been done, Porsche world have done it". Nothing is further from the truth. Compromises are made everyday in the design of products.

As for the theory behind this Plenum being discussed, it will make a difference over the stock setup. However, the biggest change will only be in the power band and not overall hp. Anytime you change the intake system, whether it's the size of the throttlebody, length or diameter of the runners or change in flow turbulance, the engines power band will change. You will not increase or decrease peak power by much, but just move the power to another area in the band.

Air moves into your engine at a peak speed of about 170 mph and the turbulance of this airflow greatly effects where the power of your engine will fall withing the rpm range. The plenum being discussed reduces air turbulance immediately after the throttlebody compared to the stock plenum so obviously there will be a change in the power band.

Peak hp cannot be substantially increased by changes to the intake system unless the mods include an increase in the volume of air. This plenum does not increase volume. All it does is smooth out the airflow at it's entry point which effects the power band. In most cases, a gain at one rpm is offset by a loss at another.

You can spend an entire semester in a Physics class dedicated to just airflow and still not understand how minor changes effect the power of an engine. It's misconceptions are a great as the belief that RAM air actually compresses the air entering the intake system. Another old wive's tail unless your car is exceeding the speed of sound.

If you simply want to change the power band by modifying the intake, you can change when or if the resonnance flap opens and closes on the NA 996's and 7's. All for free! Short of increased volume of air or reducing it's temperature, minimal peak power gains will be found with any intake mod.


Another misconception mentioned many times in this thread is that the computer needs time to learn about the new mod. This is not true at WOT. At WOT, the computer responds to "what is" and not "what should be".

 

That would be great but that would just make the entry bigger with the exits(the 2 ends of the tee) still being the same size. That is probably why Porsche had to redo the whole Intake.

Not sure we would gain anything. Somebody with an engineers background could answer this question.