Intake plenum and 911 throttle body

[KRAM36]

Originally Posted by jaykay

Nice ....so stock plenum boots can be used as the tee diameters match the plenums? This is a major potential loss area when using the 997 diverter tee.

If it puts the tb in the same you might be able to work with the stock 3.2 intake tube ....modified get the end

I don't see where the 997 Distribution T being larger then the plenum openings would be of any hindrance to the air flow. I used the stock plenum boots, no problem using them.

[jaykay]

Originally Posted by KRAM36

I don't see where the 997 Distribution T being larger then the plenum openings would be of any hindrance to the air flow. I used the stock plenum boots, no problem using them.

There is a rapid section change from the outlet diameter of the 997 diverter tee to the 3.2 inlet plenum diameter. Inside there is an exposed plenum entrance edge created by stretching the stock boots to fit the 997 diverter tee larger diameter. In 3d one could visualize this as a v-section ring disrupting airflow over it. Section changes and edges generally result in flow losses in closed piping.

This is why I am hoping that Ben has matched diameters....Ben can you verify explicitly?

Of course these assumptions have to be verified with flow testing. Torque power and throttle response being the goals.

[heliguy]

What size TB will you be using? Stock 996?

[Ben006]

yep, stock 996 TB, way bigger than the stock 68mm.
The 83mm is a bit expensive for me ... but I will make the plenum for too

[heliguy]

What is the size of the stock 996 TB?

[Ben006]

74mm at the plate 76mm at the largest.
The stock TB fits inside the 996's !

[heliguy]

WOW! We need more air. Will yours be a direct fit, basically plug and play with the 996TB? Add a 987 airbox and we are in business?

[KRAM36]

Originally Posted by heliguy

WOW! We need more air. Will yours be a direct fit, basically plug and play with the 996TB? Add a 987 airbox and we are in business?

Not quite. You will need to use the MAF housing from your 986 air box. So, you need to figure out a way to plum your 986 MAF housing into the 987 air box.

[Ben006]

Well, yes it will be a direct fit, but you will need a new intake tube, I'm working on that part too

My cel went one again ... so, I have a vacuum leak somewhere... and I think I know where ... that AOS vent line must be cracked again !
So, that makes me question the fact that we should keep it, or replace it with a standard piece of hose... Because everyone will break it during installation, so why bother ?

heliguy, where are you from ?

[heliguy]

I'm in Destin. How about you?

[Ben006]

As I said, the stock intake tube can't be reused, its tapered all the way, starting from the MAF housing. so you will not get the full benefit of the new TB.

Heliguy, I'm in Delray Beach, not very close ^^

[heliguy]

Not close at all.

[Ben006]

You are right!

And yes, the diameters match with mine

[heliguy]

Have you installed and tested it yet?

[Ben006]

didn't had the time yet, with the shifters, school, and the friends that I have over at my place :/

I should have time next week if I can take care of the shifters fast enough

[heliguy]

What shifters are these you speak of?

[Ben006]

Ball bearing short shifter !

[jsceash]

The 997 T still has the same inherent issue with turbulence
Newton' laws of physics which apply to air as well as solid matter.
"An objects in motion stay in motion until acted on by an opposing force" The air entering the T will for the most part continue in the direction it is traveling towards the back of the T.
"Every action has an equal and opposite reaction" The air striking the back of the T will rebound into the air stream causing turbulence.

Bens design Pedro Techno Torque 1 and 2 and IPD are better solutions. The incoming air hits the flat back of the stock T and compresses before it move sideways causing not one but three turbulent areas one in the back high pressure and on the top where to low pressure accumulate at the radius to the inlet to the two exits. There are Cad test drawings showing how ineffective this is in one of these threads.
Pedro system the cheapest alternative. adds a deflector V in the back creating an actual flow Y. IPD all aluminum design is molded with the same V diverter Bens is a copy of IPDs design, which I doubt he will be allowed to sell due to patents from IPD. In the end there is about a 25% improvement in this design you can't get from the stock distribution T.

Look at the video from about 7 minutes in
https://www.youtube.com/watch?v=B-fXau-xWO8

The negative on IDP is the $795 price opposed to Pedro's or Ben's design. note the IPDs design is the same and it totally coated in epoxy inside.
https://www.youtube.com/watch?v=SneTb8-cHbo

I doubt anyone who has one of these designed systems would ever go back to the factory Distribution T.

[KRAM36]

Originally Posted by jsceash

The 997 T still has the same inherent issue with turbulence
Newton' laws of physics which apply to air as well as solid matter.
"An objects in motion stay in motion until acted on by an opposing force" The air entering the T will for the most part continue in the direction it is traveling towards the back of the T.
"Every action has an equal and opposite reaction" The air striking the back of the T will rebound into the air stream causing turbulence.

Bens design Pedro Techno Torque 1 and 2 and IPD are better solutions. The incoming air hits the flat back of the stock T and compresses before it move sideways causing not one but three turbulent areas one in the back high pressure and on the top where to low pressure accumulate at the radius to the inlet to the two exits. There are Cad test drawings showing how ineffective this is in one of these threads.
Pedro system the cheapest alternative. adds a deflector V in the back creating an actual flow Y. IPD all aluminum design is molded with the same V diverter Bens is a copy of IPDs design, which I doubt he will be allowed to sell due to patents from IPD. In the end there is about a 25% improvement in this design you can't get from the stock distribution T.

Look at the video from about 7 minutes in
https://www.youtube.com/watch?v=B-fXau-xWO8

The negative on IDP is the $795 price opposed to Pedro's or Ben's design. note the IPDs design is the same and it totally coated in epoxy inside.
https://www.youtube.com/watch?v=SneTb8-cHbo

I doubt anyone who has one of these designed systems would ever go back to the factory Distribution T.

Our engines don't work like that. Our engines pull air into it, that's the force acting upon the direction and travel path of the air. Pedro blows air into the Distribution T, which will hit the back of the Distribution T and the wedge would have a nice impact on the way the air travels. Our engines pull air in and it rides along the side of the Distribution T. That's why the Y shape is very important and having the wedge is not.

Originally Posted by blue2000s

I'm using Fluent in these simulations.

A Y will be more efficient than a T for airflow in a steady state, that's correct.

Keep in mind that with three cylinders to a plenum, there is a pretty much constant flow of air into the plenum when the engine is kept at a constant speed. There is always a cylinder pulling air. The pulses that influence secondary pressure waves are important, but they are secondary in nature so the influence on flow is on a much lower order than the primary vacuum pulled by the cylinders themselves.

Here are three more simulations varying on the one I posted earlier. The first one just adds a sloped wedge to the original T. The second adds a large radius to the T junction and the last one combines the radius with the wedge.





The volume flow rate results show that the T and T with wedge have almost identical flow rates. The radius-ed T with and without the wedge are both almost the same flow rates but are about 30% greater than the standard T.

http://986forum.com/forums/general-discussions/31693-maf-throttle-body-diameter-2.html

[KRAM36]

Originally Posted by KRAM36

Our engines don't work like that. Our engines pull air into it, that's the force acting upon the direction and travel path of the air. Pedro blows air into the Distribution T, which will hit the back of the Distribution T and the wedge would have a nice impact on the way the air travels. Our engines pull air in and it rides along the side of the Distribution T. That's why the Y shape is very important and having the wedge is not.

Holy Mother of God! I was chastised over this post and 1 1/2 years later the great Jake Raby says the same thing I did about the air being pulled along the short side radius. The Y shape is the most important part of the piece, even according to Jake Raby.

Originally Posted by Originally Posted by Flat6 Innovations

No, it doesn't.

The short side radius of the IPD is where the trick is. You can't develop an intake component using a shop vac. If you do, you'll never see that what you are doing is hurting performance, or doing absolutely nothing!

With a pitot tube inserted in the intake where the splitter is installed in this photo will give zero, or very, very little velocity on the flow bench. Why? Because the air is pulled to the short side radius.

Yes, I have direct experience with this.

https://rennlist.com/forums/996-forum/944002-alternative-to-ipd-plenum-2.html#post13767949