IPD intake plenums offer considerable gains
11-17-2010, 07:31 PM
#31
Three Wheelin'
At a basic level the plenum will want to start the turbulent airflow without over exciting the flow path.
I agree that many of the aftermarket devices are an over engineered part for its intended application.
I agree that many of the aftermarket devices are an over engineered part for its intended application.
11-17-2010, 07:46 PM
#32
For reals though, your last point is spot on: it's not that critical here in regards to HP gains, at least not from a cost standpoint for Porsche as the OEM. But I've always heard that a bit of turbulence starting in the intake plenum is a good thing which promotes better A/F mixing down stream as it enters the CC's. Although I feel the surface finish just outside the intake runners as the air is fed into the CC's is more important than than way upstream in the main plenum. Just my $0.02.
+1!! At least in as much as you get out of them for the $$ paid.
11-17-2010, 07:50 PM
#33
Internal surface finish aside, this thing is a HP-gainer for other design reasons; let's not forget that! We're just saying if this thing was polished vs textured, there probably wouldn't be a huge difference. But this thing vs a stocker plenum, the dyno doesn't lie.
So.... How much does one cost? Or did I miss it in the thread? I can't find it.
So.... How much does one cost? Or did I miss it in the thread? I can't find it.
11-18-2010, 12:33 PM
#37
But, again, nobody is speaking with any authority about what constitutes desirable flow characteristics for air entering an engine manifold.
While you're thinking this over, you might want to give Boeing a call. If surface irregularity creates superior airflow for every condition all the time, they're going to be pretty red-faced about all those jets.
Fact is, I can think of a lot more devices intended to manage airflow that are smooth than that aren't. So can you. I stand by my assertion that the analogy is amusing but irrelevant.
While you're thinking this over, you might want to give Boeing a call. If surface irregularity creates superior airflow for every condition all the time, they're going to be pretty red-faced about all those jets.
Fact is, I can think of a lot more devices intended to manage airflow that are smooth than that aren't. So can you. I stand by my assertion that the analogy is amusing but irrelevant.
11-18-2010, 02:15 PM
#38
But, again, nobody is speaking with any authority about what constitutes desirable flow characteristics for air entering an engine manifold.
While you're thinking this over, you might want to give Boeing a call. If surface irregularity creates superior airflow for every condition all the time, they're going to be pretty red-faced about all those jets.
Fact is, I can think of a lot more devices intended to manage airflow that are smooth than that aren't. So can you. I stand by my assertion that the analogy is amusing but irrelevant.
While you're thinking this over, you might want to give Boeing a call. If surface irregularity creates superior airflow for every condition all the time, they're going to be pretty red-faced about all those jets.
Fact is, I can think of a lot more devices intended to manage airflow that are smooth than that aren't. So can you. I stand by my assertion that the analogy is amusing but irrelevant.
-Shawn
11-18-2010, 02:49 PM
#39
Three Wheelin'
11-18-2010, 04:08 PM
#41
Yea I can. I was one of the first adopters that bought one of these from RSS on the first Group Buy. Mine was for a 3.4 cable actuated 1999 C2. Car had 22k miles on it and was 100% stock. The IPD plenum I received had a completely smooth interior that was painted/powdercoated orange ( I have heard they no longer do the paint). There is a noticeable difference especially in throttle response and a power increase with the product vs stock. Car seemed to have more omph all through the rpm range. I later added a EVOMS and exhaust to the equation that added more air and slightly more power and better sound. Is it worth the $$? Is any of this crap worth the money? Depends....on what you want. Some here spend way way too much $$$ but hey it makes them happy.
I was discouraged with the power of my 996 after a year or so. When a Pontiac Soltice (ugly girly convertable piece of junk)can ride your butt there is a issue. I did not want to go over board with turbo or supercharger. For me it is the "law of dimished value and return" I was happy with the result the plenum, EVOMS and new exhaust gave for a while until I drove a TT, then I knew the 996 had to go. I drove a GT3 and decision was made...bye bye 996.
To all you engineering experts /naysayers - the product works as advertized. Is it worth the $$$...you decide or better yet you experts go design your own gizmo
I was discouraged with the power of my 996 after a year or so. When a Pontiac Soltice (ugly girly convertable piece of junk)can ride your butt there is a issue. I did not want to go over board with turbo or supercharger. For me it is the "law of dimished value and return" I was happy with the result the plenum, EVOMS and new exhaust gave for a while until I drove a TT, then I knew the 996 had to go. I drove a GT3 and decision was made...bye bye 996.
To all you engineering experts /naysayers - the product works as advertized. Is it worth the $$$...you decide or better yet you experts go design your own gizmo
11-18-2010, 05:07 PM
#42
Instructor
While you're thinking this over, you might want to give Boeing a call. If surface irregularity creates superior airflow for every condition all the time, they're going to be pretty red-faced about all those jets.
Fact is, I can think of a lot more devices intended to manage airflow that are smooth than that aren't. So can you. I stand by my assertion that the analogy is amusing but irrelevant.
Fact is, I can think of a lot more devices intended to manage airflow that are smooth than that aren't. So can you. I stand by my assertion that the analogy is amusing but irrelevant.
All of that said, I prefer the Top Flight Gamer V2. Good distance and good feel.
11-18-2010, 05:28 PM
#43
+1!!! (to 996Pilot's post above; the site isn't letting me quote for some reason)
I'm not taking sides and harping on "you're right, you're wrong, bla bla bla...", just that everyone should be open to everyone's ideas and opinions. Whether or not you think one analogy is a good one, try to understand it, take it for what it's worth, apply what you can. If you don't like the analogy, then do some research and come up with a better one! Or at least research it enough to say why it's not a good one, backed up with fact. For a poster to imply that someone is dead nuts wrong, I'm not even gonna listen unless they back that up with data. There are a lot of sharp people on this forum.
I'm not taking sides and harping on "you're right, you're wrong, bla bla bla...", just that everyone should be open to everyone's ideas and opinions. Whether or not you think one analogy is a good one, try to understand it, take it for what it's worth, apply what you can. If you don't like the analogy, then do some research and come up with a better one! Or at least research it enough to say why it's not a good one, backed up with fact. For a poster to imply that someone is dead nuts wrong, I'm not even gonna listen unless they back that up with data. There are a lot of sharp people on this forum.
11-18-2010, 05:53 PM
#44
There are no "sides" to take because I don't have an opinion myself. I just think it's silly to debate an engineering solution without understanding what the problem is. Nobody has yet asserted with authority what a car engine needs.
A golf ball is given speed and trajectory at launch. It's supposed to behave predictably and passively, and more really is better. An airplane exists in tension among lift, thrust, drag and gravity, and so its essentially smooth design is 'compromised' to perform in that envelope, constrained further by fuel efficiency. Neither of these situations has much to do with how you manage air that's already flowed through the airbox and MAFS and now has to be distributed to the manifold. All I do know is that the velocity of intake air is not a case of more=better/less=worse. There is a "right" amount of pressure and a "right" velocity. I'd love to learn more about that.
Too many mod debates on boards like this stem from oversimplification of engineering problems...
A golf ball is given speed and trajectory at launch. It's supposed to behave predictably and passively, and more really is better. An airplane exists in tension among lift, thrust, drag and gravity, and so its essentially smooth design is 'compromised' to perform in that envelope, constrained further by fuel efficiency. Neither of these situations has much to do with how you manage air that's already flowed through the airbox and MAFS and now has to be distributed to the manifold. All I do know is that the velocity of intake air is not a case of more=better/less=worse. There is a "right" amount of pressure and a "right" velocity. I'd love to learn more about that.
Too many mod debates on boards like this stem from oversimplification of engineering problems...
11-18-2010, 06:33 PM
#45
Three Wheelin'
Swirling air in the intake system (and inside the combustion chamber) produces a better air to fuel mix and is proven to boost fuel economy and power delivery by some 5%. High swirl intake systems give the air enough extra runner area to tumble and swirl inside improving the air/fuel mixing of the mixture.
It is believed that enlarging the ports or air flow path to the maximum possible size and applying a mirror finish is what porting is. However that is not so!Some ports may be enlarged to their maximum possible size (in keeping with the highest level of aerodynamic efficiency) but those engines are highly developed very high speed units where the actual size of the ports has become a restriction. Larger ports flow more fuel/air at higher RPM's at the sacrifice of torque at lower RPM's due to lower fuel/air velocity. A mirror finish of the port does not provide increased flow as you are stating or suggesting.
In fact, within complete intake systems, the surface is usually deliberately textured to a degree of uniform roughness to encourage fuel deposited on the port walls to evaporate quickly. A rough surface on selected areas of the port path may also alter flow by energizing the boundary layer, which can alter the flow path noticeably, possibly increasing flow. This is similar to what the dimples on a golf ball do. Flow bench testing shows that the difference between a mirror finished intake port and a rough textured port is typically less than 1%. The difference between a smooth to the touch port and an optically mirrored surface is not measurable by ordinary means. Exhaust ports may be smooth finished because of the dry gas flow and in the interest of minimizing exhaust by-product build-up. A 300 - 400 Grit finish followed by a light buff is generally accepted to be representative of a near optimal finish for exhaust gas ports.
The reason that polished ports are not advantageous from a flow standpoint is that at the interface between the metal wall and the air, the air speed is ZERO (ref to: boundary layer and laminar flow). This is due to the wetting action of the air and indeed all fluids. The first layer of molecules adheres to the wall and does not move significantly. The rest of the flow field must shear past, which develops a velocity profile (or gradient) across the duct. For surface roughness to impact flow appreciably, the high spots must be high enough to protrude into the faster moving air toward the center. Only a very rough surface does this.
The internal aerodynamics involved in porting is counter-intuitive and complex. Successfully optimizing ports requires an air flow bench, a thorough knowledge of the principles involved, and engine simulation software. (currenly utilized at our firm)
Porting by inexperienced individuals without a full understanding of the fluid dynamics of the process still continues but the results are spotty and the process is expensive and time consuming.
It is believed that enlarging the ports or air flow path to the maximum possible size and applying a mirror finish is what porting is. However that is not so!Some ports may be enlarged to their maximum possible size (in keeping with the highest level of aerodynamic efficiency) but those engines are highly developed very high speed units where the actual size of the ports has become a restriction. Larger ports flow more fuel/air at higher RPM's at the sacrifice of torque at lower RPM's due to lower fuel/air velocity. A mirror finish of the port does not provide increased flow as you are stating or suggesting.
In fact, within complete intake systems, the surface is usually deliberately textured to a degree of uniform roughness to encourage fuel deposited on the port walls to evaporate quickly. A rough surface on selected areas of the port path may also alter flow by energizing the boundary layer, which can alter the flow path noticeably, possibly increasing flow. This is similar to what the dimples on a golf ball do. Flow bench testing shows that the difference between a mirror finished intake port and a rough textured port is typically less than 1%. The difference between a smooth to the touch port and an optically mirrored surface is not measurable by ordinary means. Exhaust ports may be smooth finished because of the dry gas flow and in the interest of minimizing exhaust by-product build-up. A 300 - 400 Grit finish followed by a light buff is generally accepted to be representative of a near optimal finish for exhaust gas ports.
The reason that polished ports are not advantageous from a flow standpoint is that at the interface between the metal wall and the air, the air speed is ZERO (ref to: boundary layer and laminar flow). This is due to the wetting action of the air and indeed all fluids. The first layer of molecules adheres to the wall and does not move significantly. The rest of the flow field must shear past, which develops a velocity profile (or gradient) across the duct. For surface roughness to impact flow appreciably, the high spots must be high enough to protrude into the faster moving air toward the center. Only a very rough surface does this.
The internal aerodynamics involved in porting is counter-intuitive and complex. Successfully optimizing ports requires an air flow bench, a thorough knowledge of the principles involved, and engine simulation software. (currenly utilized at our firm)
Porting by inexperienced individuals without a full understanding of the fluid dynamics of the process still continues but the results are spotty and the process is expensive and time consuming.
Last edited by CWhaley; 11-19-2010 at 09:54 AM.