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996 Turbo / GT2 Turbo discussion on previous model 2000-2005 Porsche 911 Twin Turbo and 911 GT2.
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  #46  
Old 08-20-2012, 10:26 PM
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Correct on the golf ball. The golf ball needs the dimple in order to reduce drag because it is going head on against wind = drag. It is to reduce the drag. BUT in the throttle body, it is not going head on against the wind. It is just the walls....apples and oranges. Very different concept.
 
  #47  
Old 08-21-2012, 12:05 AM
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[QUOTE=f1crazydriver;3621249]The golf ball needs the dimple in order to reduce drag because it is going head on against wind = drag. It is to reduce the drag. QUOTE]

The dimples on a golf ball creates less drag over the frontal surface area as opposed to a smooth ball.
 
  #48  
Old 08-21-2012, 12:37 AM
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sorry had too..

From 1993 to 1998, Honda's only presence in F1 was as an engine supplier through its closely related but independent partner, Mugen Motorsports, who supplied engines to Footwork, Lotus, Ligier, Prost and Jordan. Mugen-powered cars had won 4 Grands Prix by the end of the 1999 season. In 1998, Honda was seriously considering entry in Formula One as a constructor, going as far as producing an engine and hiring Harvey Postlethwaite as technical director and designer. In addition, Honda pulled engineer Kyle Petryshen from HRC to help with the design, implementation and management of the new engine in the new chassis.[4] A test car, RA099, designed by Postlethwaite and built by Dallara, was made and tested during 1999, driven by Jos Verstappen. The team impressed at test sessions, beating some more experienced and better financed teams, even if they were mostly in the midfield. At a test of this car, Postlethwaite suffered a fatal heart attack, the project was later shelved and Honda decided to merely recommit as a full works engine supplier to BAR, starting in 2000.

But if you look up the car,

http://en.wikipedia.org/wiki/Honda_RA099

There is no mention of you? I wonder with your background why you would not just pick up the phone and call one of motorsports engineers for Porsche and get all the answers you seek. Oh since you are a F1 engineer then you surely know the engineer that was one of the team who wrote the code for our ECU?

I do agree with you on this tho, "All I can say is OH GOOD LORD why do I even bother"
 
  #49  
Old 08-21-2012, 08:44 AM
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[quote=996TWINS;3621284]
Originally Posted by f1crazydriver View Post
The golf ball needs the dimple in order to reduce drag because it is going head on against wind = drag. It is to reduce the drag. QUOTE]

The dimples on a golf ball creates less drag over the frontal surface area as opposed to a smooth ball.
Yup... but in this case of the TB, their is no frontal area that needs drag reduced, right ? So this theory shouldn't apply ? Also, does it make a difference that in the above analogy, the ball is going against wind resistance while in a TB, you are getting a vacuum (suction) in wards...
 
  #50  
Old 08-21-2012, 09:23 AM
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From Plenums to Golf *****..This is an informative thread, learning new things every day...
Aerodynamics
When a golf ball is hit, the impact, which lasts less than a millisecond, determines the ball’s velocity, launch angle and spin rate, all of which influence its trajectory (and its behavior when it hits the ground).
A ball moving through air experiences two major aerodynamic forces, lift and drag. Dimpled ***** fly farther than non-dimpled ***** due to the combination of two effects:
First, the dimples on the surface of a golf ball cause the boundary layer on the upstream side of the ball to transition from laminar to turbulent. The turbulent boundary layer is able to remain attached to the surface of the ball much longer than a laminar boundary and so creates a narrower, low pressure, wake and hence less pressure drag. The reduction in pressure drag causes the ball to travel farther.[7]
Second, backspin generates lift by deforming the airflow around the ball,[8] in a similar manner to an airplane wing. This is called the Magnus effect. Backspin is imparted in almost every shot due to the golf club's loft (i.e., angle between the clubface and a vertical plane). A backspinning ball experiences an upward lift force which makes it fly higher and longer than a ball without spin. (see Baez[9]) Sidespin occurs when the clubface is not aligned perpendicularly to the direction of swing, leading to a lift force that makes the ball curve to one side or the other. Unfortunately the dimples magnify this effect as well as the more desirable upward lift derived from pure backspin. (Some dimple designs are claimed to reduce sidespin effects.)
To keep the aerodynamics optimal, the golf ball needs to be clean, in order to avoid any impediments to the aerodynamic effect of the ball. Thus, it is advisable that golfers frequently wash their *****. Golfers can wash their ***** manually, but mechanical ball washers are also available.
.....Sorry to say that I didnt write this,,got it off the internet...I dont know Jack about golf But now I know more about *****...LOL..
 

Last edited by johnspeed; 08-21-2012 at 09:28 AM.
  #51  
Old 08-21-2012, 11:47 AM
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I have found that guys with smooth bald heads can run faster than guys with cratered bald heads. Just sayin
 
  #52  
Old 08-21-2012, 12:16 PM
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You opened a can of worms John.

Originally Posted by johnspeed View Post
From Plenums to Golf *****..This is an informative thread, learning new things every day...
Aerodynamics
When a golf ball is hit, the impact, which lasts less than a millisecond, determines the ballís velocity, launch angle and spin rate, all of which influence its trajectory (and its behavior when it hits the ground).
A ball moving through air experiences two major aerodynamic forces, lift and drag. Dimpled ***** fly farther than non-dimpled ***** due to the combination of two effects:
First, the dimples on the surface of a golf ball cause the boundary layer on the upstream side of the ball to transition from laminar to turbulent. The turbulent boundary layer is able to remain attached to the surface of the ball much longer than a laminar boundary and so creates a narrower, low pressure, wake and hence less pressure drag. The reduction in pressure drag causes the ball to travel farther.[7]
Second, backspin generates lift by deforming the airflow around the ball,[8] in a similar manner to an airplane wing. This is called the Magnus effect. Backspin is imparted in almost every shot due to the golf club's loft (i.e., angle between the clubface and a vertical plane). A backspinning ball experiences an upward lift force which makes it fly higher and longer than a ball without spin. (see Baez[9]) Sidespin occurs when the clubface is not aligned perpendicularly to the direction of swing, leading to a lift force that makes the ball curve to one side or the other. Unfortunately the dimples magnify this effect as well as the more desirable upward lift derived from pure backspin. (Some dimple designs are claimed to reduce sidespin effects.)
To keep the aerodynamics optimal, the golf ball needs to be clean, in order to avoid any impediments to the aerodynamic effect of the ball. Thus, it is advisable that golfers frequently wash their *****. Golfers can wash their ***** manually, but mechanical ball washers are also available.
.....Sorry to say that I didnt write this,,got it off the internet...I dont know Jack about golf But now I know more about *****...LOL..
 
  #53  
Old 08-21-2012, 12:33 PM
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It seems my results do that But I am not afraid of posting the truth in what I find out..
Its all good if we learn something But some live in a tunnel and release the worms..LOL..
 
  #54  
Old 08-21-2012, 01:13 PM
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[quote=f1crazydriver;3621431]
Originally Posted by 996TWINS View Post

Yup... but in this case of the TB, their is no frontal area that needs drag reduced, right ? So this theory shouldn't apply ? Also, does it make a difference that in the above analogy, the ball is going against wind resistance while in a TB, you are getting a vacuum (suction) in wards...
Agree. I was only referring to the golf ball analogy.


This thread almost makes me want to go back into engineering. Ahh, the memories.
 

Last edited by 996TWINS; 08-21-2012 at 01:18 PM.
  #55  
Old 08-21-2012, 02:05 PM
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Although, I have no clue if the IPD y-pipe works I can safely say that the golf ball comparison is irrelevant in this case.

However, I will have to side with IPD that slightly rougher vs smooth is not going to make much of a difference here. The air traveling in these pipes prior to y-pipe is making lots of turns and expansions. Because of this, the flow is not laminar, but likely more turbulent. In this case a rough wall, will not have as much of an effect on the flow. Additionally, even if it did, due to the short distances involved, the pressure drop would be infinitesimal. Additionally, enlarging the y-pipe diameter has more of a positive effect on friction loss than the rough internal finish. So the lower velocities through the ipd for the same cfm translates to lower friction losses. Again, I am not saying that the ipd plenum works, just that the argument that the smoother internal will have an improvement is probably so minor that it would not be measurable and the larger pipe size of the ipd would more than offset that.
 
  #56  
Old 08-21-2012, 02:46 PM
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Hi 951, The ID of the stock plenum legs and IPD are about the same , around 80mm.
Though the splitter takes up most of the cross section volume compared to stock.
 

Last edited by johnspeed; 08-21-2012 at 04:04 PM.
  #57  
Old 08-21-2012, 03:17 PM
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Originally Posted by johnspeed View Post
Hi 951, The OD of the stock plenum legs and IPD are about the same , around 80mm.
Though the splitter takes up most of the cross section volume compared to stock.

Yeah, but I am pretty sure the ID, which is the important part is larger, since the IPD is much thinner than factory. But I could be wrong. Either way, the length of either system and the fact that we are not talking pure laminar flow makes it a very minimal issue, IMO. But this has nothing to do with the real point that you brought up that it did not work in your application. You are not the first person I heard this from. I almost pulled the trigger 2 years ago on this, but on private emails, I was told it did not work, in spite of many saying it does. So I am still confused about it.

The IPD plenum has a center divider that transitions flow and restricts the balance between left and right bank. The F6 will pulse back and forth through the center plenum, but it cannot do this with the IPD unit. Again, I did not invent this, it was told to me, so I cannot verify if it's true and would really like to know if the IPD works as just by looking at it, I would have thought that it would work.

I am going to be doing a bunch of dyno tests to tests some different IC's over the next few months. I have considered getting one and installing it and running another dyno. But, just because it does not work for my system does not mean it wouldn't for another.

here is a post that explains exactly what I heard:

Originally Posted by bbywu View Post
The M64 block is probably the single most developed engine in Porsche's flat-6 repertoire. The plenum in those cars work by equalizing flow between both banks. As the engine runs the "on/off" status of the valves across each bank create pulses and slows flow. A T shape plenum system allows slowed air traveling from the bank that is closed to travel to be redirected to the other side. A Y shaped plenum does not allow this to happen as flow is directed to only one side.

At low RPMs, this pulse effect is much greater. At higher RPMs, the flow redirection is not as significant as the duration of the banks closing is much shorter.

Here is a close up of a GT3 cup car. It absorbs pulses from either side, without using a soft Y curve in its design.



Testing of larger bore T shaped plenums have shown similar gains when matched with an appropriate throttle body.


This is my understanding of how the airflow is directed in a flat 6 engine. If there is someone with contrary facts, please correct me.
 
  #58  
Old 08-21-2012, 04:10 PM
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951 ,Yes I meant 80 mm ID,not OD ,on both..
Did you see my Dyno sheets with the comparison on the thread I posted with that modified plenum from Tim?https://www.6speedonline.com/forums/...up-friday.html
 

Last edited by johnspeed; 08-21-2012 at 04:33 PM.
  #59  
Old 08-21-2012, 05:21 PM
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Originally Posted by johnspeed View Post
951 ,Yes I meant 80 mm ID,not OD ,on both..
Did you see my Dyno sheets with the comparison on the thread I posted with that modified plenum from Tim?https://www.6speedonline.com/forums/...up-friday.html

I will check it out and I'll take your word for it about ID. However, the info provided above on why these plenums don't work may be the reason in addition to the fact that it is the same diameter. But the pipe wall roughness may not be. Interesting dyno. No difference basically. quite interesting. So where are the dyno's showing that it actually increased hp by 30-40?
 
  #60  
Old 08-21-2012, 08:04 PM
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Originally Posted by Prche951 View Post
Yeah, but I am pretty sure the ID, which is the important part is larger, since the IPD is much thinner than factory. But I could be wrong. Either way, the length of either system and the fact that we are not talking pure laminar flow makes it a very minimal issue, IMO. But this has nothing to do with the real point that you brought up that it did not work in your application. You are not the first person I heard this from. I almost pulled the trigger 2 years ago on this, but on private emails, I was told it did not work, in spite of many saying it does. So I am still confused about it.

The IPD plenum has a center divider that transitions flow and restricts the balance between left and right bank. The F6 will pulse back and forth through the center plenum, but it cannot do this with the IPD unit. Again, I did not invent this, it was told to me, so I cannot verify if it's true and would really like to know if the IPD works as just by looking at it, I would have thought that it would work.

I am going to be doing a bunch of dyno tests to tests some different IC's over the next few months. I have considered getting one and installing it and running another dyno. But, just because it does not work for my system does not mean it wouldn't for another.

here is a post that explains exactly what I heard:

There a few items that do not fit in with the turbo motor. One the pic you show is of the 6 throttle body intake system. Not even remotely close other then it will bolt to the head. Also that intake was developed to work with restrictors.

Yes at low speed there is a pulse but the turbo motor has a low and high lift cam the low lift helps to minimize the effect. The gt3 does not have high and low lift, only retard or advance so the pulse is much greater at lower engine speeds. Also do not forget that a turbo is forcing the air charge in and not the vacuum of the piston dropping. That changes things too.


I used the IPD because it used a 74mm tb then after testing I cut the back out and never said boo about it because everyone is drinking the cool aide. That was in 07. Does the IPD work? Yes it does. where it works is the question. I feel they should add a T style to there line just with the 74mm tb on it.
 

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