78mm plenum with a stock throttle body, correct?

 

That is correct for all of the photos above.


I will have 82MM Plenum with enlarged ( GT3 ) TB dyno shortly.

 

The design of an intake air system is major factor in volumetric-efficiency of the engine. Any abrupt changes causes pressure drops resulting in less air entering the combustion chamber. The intake air path should always have smooth transitions nothing abrupt to cause turbulence, same principles hold true for the exhaust.

If your theory where true we would not need multi-angle valve jobs or specially designed intake plenums since those are past the throttle body.

A quick study on fluid dynamics might enlighten you a bit.

 

Thanks for your input ISIS. Unlike a Supra, how the Porsche engine works at this component is different. If the Y or T was such a big factor, then the results on both our 996TT and 997TT plenum would not be where they are.

Rennsport - The plenum is 78mm but the throttlebody is not which is the restriction on that part, that is why we built ours to use a larger throttle body. Whatever the smallest diameter is at any point of the system is the restriction. I have dynoed the 78mm one as well here on our own dyno. I have seen your dyno sheets before, have you dynoed it independently yourself?

Best of luck to the OP and the others trying to make a point. I am out.

 

I would have posted this as PCA Technical however this site requires me to post under Softronic.

The Boxer engine operates in pulses from bank to bank in which is why Porsche has used what we are calling a T design. This pulsation creates a frequency or resonance and is why the NA engines use a Resonance flap also. This design has been used since the 1983 L jetronic Carrerra for the plenum. The resonance flap has been used in the NA cars since the 964 introduction. The Porsche designed intake also is made this way so that the pulses are absorbed in the intake rather than them being redirected upstream towards the TB in which would create turbulence. Porsche has had many years to make changes if they wanted to the design if they thought it would benefit it. The cost would not be the issue as the Cup cars use the same design .





Best ,
Scott Slauson

 

Guys, so what is the verdict?

bigger throttle with T pipe?

 

What makes you think that adding a slightly larger throttle body will make 45 more HP and 60 more TQ? Its not possible. What could be possible is that your dyno testing is SKEWED and you can make your product measure whatever gains you want. Porsche engineers must be Friggin STUPID leaving this power on the table !!!! A few more millimeters with a simple throttle body upgrade that could add an extra 60 TQ. Also, why no power gains on top?

I have owned and modified a few Porsches and I have a new 2010 turbo on the way. I don't post often but I read the forums regularly. I have modified my cars with companies that offer real results and not BS hype like this. I just can’t fathom how people reading this can believe that this mod can add 45 hp and 60 tq. From what I can ascertain from other mods like this, 15 more HP and TQ is realistic. Also, if you are going to advertise the best gains for your upgrade, why not point out that at 4380 RPMS on your graph the HP and TQ gains are a staggering increase of 70 HP and 80 TQ <O</O

 

Hi 993rscs, nice peaceful first post on the forum! Just kidding.
If I were you I would NOT do anything at the moment. I assume by the "whole works," you are doing extensive modification to the ECU/turbo? If so it's best to stay with one tuner company and follow the package offered by that one company alone (each tuner offers different packages -- the "stages"-- depending on how much power you want). This is important because the software is tuned according to the hardware; you don't necessarily want to mix a software with a hardware that it was NOT designed with, wrong header for example.

So first, do some research and pick out the tuner that you are comfortable with. Some of the more established ones, and the ones I would choose from, are, in alphabetical orders , EVOMS, GIAC/AWE Tuning, Protomotive, and Switzer. They are all sponsors here (except maybe Protomotive?) and could be contacted easily. Once you have chosen a package from a tuner, call him and ask for guideline as to what to to. Do not just get a plenum now.
The plenum is a "controversial" upgrade, and I would bet if you were to ask 10 good Porsche vendors, 9.5 would tell you it is NOT necessarily the first step towards more power. A stage 2 -- exhaust and ECU upgrade -- is. (And remember to fire the 0.5 vendor who tells you to start with the plenum.) Plenum, throttle body, header, etc., are usually saved for later stages, they have trade-offs (loss of power down low as mentioned here with too large throttle body, and same risk with header), and not the first upgrade that comes to mind in a stock car.

For the record, anyone please correct me if I am wrong, but there has not been an independent dyno (i.e. one NOT done by vendor, with proper before and after runs) that shows a reliable increase in horse power with plenum, let alone 45 hp. Happy New Year. Hope this helps & good luck and have fun!

 

The only point I am trying to make is that you cannot change the basic laws of physics, or at this level common sense. You say it does not matter if it is a Y or a T. An abrupt 90 tee will not flow as smooth as a Y. Below is a picture of a velocity profile for a typical tee albeit it is only showing flow to one side but you see what is happening.

The blue area is lower velocity and the red is higher.



Can you explain to me why basic laws of physics do not apply to your part?

 

Guys, Y plenum will produce less back pressure, that's the only difference.
Think about cooler end tanks, you may have cooler with nice shape end tank or not, both are working somehow.
My free lancer tuner test ipd for Korean friend, didn't find any difference, later he used gt2 intake.
but I think kit like this will add some power on highly modified car and no diferenc would be if it's Y or T.
I'm only not sure if 2mm difference (cayenne versus TT) is big enough?
What do you think?

 

FWIW, I agree with cannga. Go with a single tuner, and don't make upgrades in a piecemeal manner. I would add AWE to the list, as well as some of the Euro tuners. I would use Switzer Performance Innovation, but I am biased.

 

will this fit for the 997GT2?

greetings