IPD intake plenums offer considerable gains

IPD intake plenums has just assigned SpeedMerchants Motorsports as a master distributor. I wanted to bring these plenums to everyones attention (in case you haven't heard) and the horsepower gains have surprised many sceptics. 996 Carrera 3.6L 24hp and 22tq Dyno Sheet Here 996 Carrera 3.4L 25hp and 22tq Dyno Sheet Here 996 Turbo w/68mm TB 30-35 hp gain Dyno Sheet Here 996 Turbo w/74mm TB 35+ hp gain 996 GT3 24hp gain Dyno Sheet Here PM me for individual price quotes or for more info. We also have all the plenums up on our website. www.speedmerchants.ca John

The dyno info on the IPD website shows low RPM torque gains. I've been skeptical but they do offer a 30 day money back guarantee...tempting.

Agreed, with a money back guarantee you cant go wrong. We were sceptical and dyno'd a car before bringing on the IPD line. As always with Speedmerchants we race and use what we sell. http://www.flickr.com/photos/speedmerchants/5181542035/http://www.flickr.com/photos/speedmerchants/5181542035/ by http://www.flickr.com/people/speedmerchants/, on Flickr

I am surprised why don't they polish the inside ? wouldn't that be better for air flow ?

I have one of these. I don't pay much attention to the numbers, but I will say that the difference was perceptible (which is all that really matters). Seat of the pants, the before vs. after was more noticeable than, for example, my Revo flash was.

I went to your website and could not find the one for my 996 3.4L? Is this a DIY?

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Smoother isn't always better when it comes to making power. A little bit of disruption in the airflow promotes better mixing of the air and fuel in the cylinder. -Shawn

For years the thought was to increase flow you had to polish the surface... When actual analysis proved a small amount of roughness did increase the fuel/air mixture.... The true porting job will remove the "AS CAST" surface and open up the ports improve flow by eliminating obstructions while maintaining a certain level of turbulence (fine balance here as too much will hinder flow as well). We started doing this on motorcycles over 30 yrs ago (my father has a natural talent at the balance between smooth & rough)

Ever see smooth polished golf *****?

A golf ball is a great comparison...

John, a bit OT but what octane rating was the fuel you were you using for those dyno runs?

Those dyno sheet links are dead

forget dyno how about 0-60.....

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Maybe 5-60 to eliminate the traction issue, but I would like to see some street/track numbers if anyone had them.

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Not really. A golf ball's engineering problem is ballistic.

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I'm going to go ballistic. Is this a golf forum??

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+1. I sure hope NOT!

+ infinity.

So does the god d@mn thing work or not ??

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Depends on how you define 'work'. If you need a number to brag about, tough to get an objective measure that everybody will accept around here. But if you just want to feel something, my experience was that it had a noticeable positive effect. And unlike my other breathing-oriented mods, the butt dyno feeling didn't disappear after the first week. Compared to the cost of an ECU flash, for example, I thought this was pretty good value. My indie even approved, despite the fact I didn't buy it from him. Caveat: I have the EVOMs intake, EVOMs exhaust and Revo flash. YMMV.

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Right on

Actually, Yes... The dimples create the ball to push air around the sphere... which generates controlled air flow... each indentation has a constant, predictable flow characteristic. Basic Fluid Dynamics.

I like Bridgestone E7's myself. I'm over the whole Titleist thing.

I though the dimples on a golf ball were to induce slicing?

+1 on the Bridgestones

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Sorry, but I really do think it's irrelevant. The golf ball is about trajectory and managing the force of impact of the club on spin. Even though the dimples are about 'airflow' as you say, they're there to accomplish an utterly different task than any automotive intake is charged with. Moreover, the dimples are uniform and at regular intervals, which you can't say about the effect of casting. I don't think it explains the benefit of a rough surface on the inside of an intake plenum at all.

The controlled airflow from the dimples are exactly what you are looking for in the intake system. Random flow will generate inconsistent results that become problematic. The better job you do of creating a consistent flow path the greater result you have in the mixture.

The golf ball is a decent way to get the point across. It's about the boundary layer of air on and very near the surface, described from a perfectly laminar flow to varying degrees of turbulence. The dimples in a golf ball promote turbulence, and like another poster said, allows the spin of the ball affect it's flight path (a smooth ball would not because there would be no pressure gradient). Now if someone brings up Reynolds numbers, the party is OVER. So should an intake be polished? A small amount of turbulence is good to reduce drag in curtain applications, and from what I've read, an intake can benefit from not being completely void of surface finish. Don't be a hater, I tried my best to make the golf ball JPEG more palatable to the the forum.

Thanks for getting my point across... I was next going to give a lesson in fluid Dynamics that would have BORED the daylights out of everyone!

A fun discussion, but what's missing for me still is a clear understanding of what's required for air delivery between the airbox and the manifold . Everybody is waving their laminar flow around without being able to say with certainty what the engine actually wants. I get golf *****. What I don't necessarily buy is that what's good for a golf ball is good for 100% of all airflow engineering problems. From my limited understanding of these things, an intake system's job is to deliver adequate airflow for the engine to pump, at the appropriate temperature and pressure versus that in the manifold (this latter being the key difference between a good aftermarket CAI and a bad one). From eyeballing the setup on my engine, it seems to me that the plenum's job in that process is to funnel the air from the airbox into the manifold without adding any effect to it at all. Porsche's own engineering of the OE plenum suggests that this part isn't really all that sensitive. It's a classic bolt on: a nice little effect created by a massively overengineered replacement part.

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.

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Not me!! +1!! Totally behind you 100%. The key here is to fill your intake plenum with golf *****, then you KNOW the turbulence is the best answer. 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.

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.

$850 or so

skip to 2:30

great episode!

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.

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It's not clear to me whether the analogy has any merit. Certainly smoother surfaces yield less flow resistance to fluids. So if your goal is strictly to have the maximum amount of flow over a surface in a given time then smoother is better. That said, it is my understanding that the air/fuel distribution within the cylinder is improved by introducing some turbulence. Finding that balance is the the magic. Adding dimples to a surface is a way to break up the boundary flow layer along walls and therefore introduce a controlled amount of turbulence. So adding dimples to an intake tract may be another way to reach that magic balance. I've never tested it and my expertise isn't specifically in fluids so I'd like to see measurements to answer the question. -Shawn

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You are entitled to your opinion.

We know who the real nerds are here. haha. Back on topic. Besides BruceP, can any other owners of this mod offer comments/numbers/observations?

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

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Look again Bruce, on the top side of most wings (and other "laminar flow" airfoil surfaces) you'll probably see a whole bunch (of what looks like) little pieces of sheet metal standing on end, evenly spaced at opposing (seemingly) random angles. These are called "vortex generators" ( http://en.wikipedia.org/wiki/Vortex_generator ) and actually create controlled turbulence (much like the golf ball dimples create a controlled turbulence). This turbulent airflow can increase in velocity compared to the laminar flow air due to boundary layer effects ( http://en.wikipedia.org/wiki/Boundary_layer ). In the end (in some cases), velocity (over a surface) can be increased with turbulent flow rather than laminar flow. In fact MOST devices used to manage airflow ARE NOT smooth but rather are something that upsets airflow in a controlled fashion. All of that said, I prefer the Top Flight Gamer V2. Good distance and good feel.

+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.

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...

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.

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Ever think of being the copywriter or marketing for these guys?

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Oversimplification. Engines suck.

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They reached out and I had a stop my swirling too Blow them off....

$850??? My gosh what a rip. $200 is more reasonable for a chunk of metal. I hate how everyone boosts the price of everythign because its a Porsche. Example: oil filter for my Audi $8 vs oil filter for the 996 $15-20 for a stinking filter element.

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I agree 100% - it is ridiculous how porsche anything has to cost +3X anything else

Is a tune necessary when installing this intake?

no not necessary -

Porsche charges $16,900 for the Carrera Power Kit (option X51) which adds 23 HP (for the current 997.2 S models) and is comprised of: modified cylinder heads, carbon-fiber air filter casing (upper part), new variable double resonance intake manifold, sports exhaust system featuring specially designed twin dual-tube tailpipes, modified engine management. Do you guys really believe that Porsche would go to all of that ^ trouble if they could get the same HP from a simple plenum change? At least I got this in the correct thread this time!

Well if you look at the dyno charts it is only a midrange HP increase, not max power. Porsches Powerkit adds 23hp to the full output numbers.

Peak numbers mean very, very little to me. I look at average HP and torque gains and consider what any enhancement is doing to an engines drive-ability and overall performance. I have 3 dynos in house, including the only M96/97 specific engine dyno cell in North America, but I learned long ago that making engines that perform really well on the dyno and make super impressive peak numbers are generally lacking whats necessary to put a long term smile on the owners face. Dynos are tools that allow us to design very effective engines. Honestly, net output on the dyno are the two channels that I use less than everything else. I collect my own data and don't depend on anyone else's. Claims and adverts mean very virtually nothing to me as I understand the variables associated with general component evaluations, primarily made for marketing purposes. Nothing wrong with marketing at all, I do enough of my own.. But when I rate an engine I average my highest and lowest numbers with the peak maximum and minimums taken out of the equation. Most others won't do this. I've seen a 3,000.00 exhaust system make 30HP LESS than a stock unit on a stock engine, which was 50HP less than the adverts claimed it to be. That company didn't even extend the common courtesy of responding to my email that stated why this occurred. I suppose it had too much data concerning WHY the system wasn't performing, to include exhaust gas temps of each cylinder during the comparatives. I tested that system on six different engines with the same results. Until I see it with my own eyes, I don't believe it.. Most others should do the same. My post in no way is making any statements about any company or any individual component and should only be perceived as a "general" statement concerning components, performance evaluations and reality of any component or engine as a whole. Making power is difficult, making power where it needs to be is the most difficult. Want to make more power, create a component that enhances output at a higher RPM and the equations are already in your favor. Will that power be usable on the street? Will the mods necessary to create the higher level of power at higher RPm actually hurt mid-range performance? My goal is to create an entire engine that makes big power and no single component is the key to that level of performance. Its all in the combo. That combo starts at the air filter and extends to the outlet of the tailpipe.

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but thats German HP... in all reality your getting more power than advertised vs power you might be getting than advertised. You get what you pay for... I for one like than plenum, its cheap for the power that you might be getting.

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With all of that said, have you ever tested the components being discussed? It would be interesting to hear feedback/results from someone with no commercial interest in the product. -Shawn

Yep.. Most ratings for European components are rated in DIN, not SAE power.. The differences aren't huge, but are notable. It would also have a good chance of creating a thread that offers no benefit to anyone. I keep my info within the confines of my compound, since it costs thousands of dollars to collect it. No one "assists" me with the bills associated with that or the cost of the evaluation equipment. What I wanted to convey in my post was the fact that peak output enhancements don't offer much at all in the true overall performance of an engine. People should always consider the big picture when choosing a component. Do the research to understand what the enhancements effect and how that might effect your application. Believe nothing of what you hear and only half of what you see and you'll never have over-expectations for components.

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Ahh, the X51 defence. All due respect, this argument betrays a little naivete about both engine output and marketing. Product claims for bolt on mods are not usually straight up lies. They are usually supported by tests that may or may not be repeatable methodologically and, more importantly, are based on peak horsepower. Peak horsepower is a BS number of interest only to teenaged boys and bench racers. To everyone else, what matters is how an engine makes that power, and at what cost to driveability, NVH, durability, emissions and reliability. The X51 does it "right" in the sense that the power gains are useful and usable, and nothing else other than cost is sacrificed. That said, not every bolt on is a terrible idea. Lots of track guys would like a few extra ponies at the peak and the ability to shift a little later. Value is one thing, but it's not really all that helpful to write off an entire industry as liars and charlatans. I can assure you from years of experience with this that every advertising claim has to be supportable if challenged, however tenuously. In my business, we refer to this as "the best face of the truth." But honestly, the "why would Porsche leave power on the table" debate isn't much help here. A better question would have been why Porsche didn't build this engine that way in the first place.

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I reviewed mine a couple of pages back. I like it. But that needs some context: I'm not that concerned with what the numbers are resulting from my mods. I can't imagine anything less relevant to the way I use my car. What I've wanted to do is change the personality of the car a little bit. I wanted it to be a little less civilized and a little more rowdy, without being a track car or a boy's toy. A sports car, but not a race car. So, powertrain-wise, I did the SSK, the intake, the exhaust (but not headers), the plenum and an ECU flash. I got what I wanted, which is an engine I can hear and get feedback from, and one that sounds just the slightest bit antisocial. I'm happy with the result, which integrates nicely with what else I've done to the car. Which is really the point. Don't buy mods because you're afraid you're missing out on power. Do it because they'll personalize the car. This stuff is, for most of us, subjective , though a lot of car guys hate to admit it. PS ... and the final touch, my RS engine mounts are on. I get the car back Monday. Can't wait!

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Well said! Now if only the vendors would say the same thing instead of posting highly dubious objective claims.