what does this tell 996TT owners that Porsche got it wrong and it needs to curved like the 997 TT ??

 

Well, the fact is, the freer the flow, the less bends, the more gradual the bends and the smoother the surface, the less the air is heated and decompressed. Appllies to all moving gases and liquid, whether it is your car or you home plumping. Therefore, any reduction in things that interfere with the flow of the air will gain you power.

 

Curved intake plenums are available for the 996TT -- I got mine from Speed Gallery: (818) 766-2321.



Craig

 

Did you notice the power increase? Would it benefit a Stage II car?

 

I did it in conjunction with several other mods, so I can't attribute the powerr increase, or any portion thereof, to the intake plenum or any other individual mod. That being said, I have read reports of quantifiable power gains associated with this intake planum in the 25-33 HP range (I have no idea regarding the accuracy of these figures).

Craig

 

Basically you should have a plenum chamber connected to your runners that is big enough to supply a cylinder (engineered to the exact size of each cylinder) and so that degeneration rhythms see outside air so it can reverse and go back into the tract .

On way is to mount a throttle plate on the front of a plenum but you lack individual cylinder control.

Differences in power and torque between straight or curved comes from having different manifold designs. Porsche choose the curved to bust torque.

By design, a curved gives more torque since the extra micro turbulence promotes a good mixture , and straighter type being better for power since it does not change direction and cause friction on the inlet charge.

Mechanical engineers have been working with these designs for 100 years. I think Porsche engineers are just trying to bring new technologies into production to differentiate the 996 from the 997 and bolster sales.

 

Great post pca911turbo. Can you please explain how the curved unit creates more turbelence than the OEM piece?

"By design, a curved gives more torque since the extra micro turbulence ..."

I would assume there to be less turbelence in a graduated curve than a "T" intersection.

Mike

 

It is due to the principals of fluid dynamics. Hard to explain unless you take a few years of classes in physics, chemistry and engineering principals.

 

Have you ever seen an Eddlebrock "Torquer" manifold that run on V8 engines? By design, the carburetor is torqued 15 degrees to one side and the intake manifold curves and swirls the air and fuel. This design creates torque.

 

What Edelbrock did was increase the plenum volume and alter the short-side radius of the runners, to give the air/fuel charge a straight shot at the intake valves. That straight shot produces a potent power build from 2,500 to 6,500 rpm.

 

I was hoping I could skip all that and just ask you

Hey - You're robertp! I thought the 2 posts were too close to be a coincidence.

I understand how the curved unit can create a swirling effect.

But what, under any circumstance, would a "T" intersection be more effective (if any). I guess my question is - what's the downside of the graduated curve intake plenum relative to the characteristics provided by the OEM "T" unit (from a scientific perspective).

Mike

 

OK I'm either an idiot or this is the most ridiculous post I've seen in a while...WTF is "Porsche choose the curved to bust torque"? In the next sentence it says "a curved gives more torque"...I must need a dictionary. "straighter type being better for power"...Are you saying curved gives more torque, but less power? I have studied physics, chemistry (my degree) and engineering and can't quickly grasp why the straight "T" shaped design will allow for better flow than the curve. My only question wwould be is the difference in improved flow (with the curved design) that significant?

 

A "T" shape or 90 degree angle is the worst thing you can do for any intake or exhaust. It severely restricts flow and mixtures. A graduated curve intake plenum has a more subtle change to it and, thus, less restrictive producing better flow and more TQ/HP. I talked about "straight" not "T" shape. A "T" shape is the most restrictive shape for any fluid dynamic flow. I have taken fluid dynamics in college and it is my understanding that curved will produce more TQ. Maybe that is why Porsche went with that design this time around!

 

Obviously a curved intake will have less turbulence than a "T". The Edelbbock Torquer carburetor pad was angled to even up the cylinder to cylinder fuel distribution variation.

 

And that evening up does what to the air flow (less angular blockage)? It promotes better micro turbulence and thus, more TQ.